From 34a148bf0911a4a1cae85f8ecba57affb4d76aee Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 9 Jan 2009 12:27:09 -0800 Subject: kernel/trace/ring_buffer.c: reduce inlining text data bss dec hex filename before: 11320 228 8 11556 2d24 kernel/trace/ring_buffer.o after: 10592 228 8 10828 2a4c kernel/trace/ring_buffer.o Also: free_page(0) is legal. Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8b0daf0662e..9542990f515 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -133,7 +133,7 @@ enum { }; /* inline for ring buffer fast paths */ -static inline unsigned +static unsigned rb_event_length(struct ring_buffer_event *event) { unsigned length; @@ -179,7 +179,7 @@ unsigned ring_buffer_event_length(struct ring_buffer_event *event) EXPORT_SYMBOL_GPL(ring_buffer_event_length); /* inline for ring buffer fast paths */ -static inline void * +static void * rb_event_data(struct ring_buffer_event *event) { BUG_ON(event->type != RINGBUF_TYPE_DATA); @@ -229,10 +229,9 @@ static void rb_init_page(struct buffer_data_page *bpage) * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing * this issue out. */ -static inline void free_buffer_page(struct buffer_page *bpage) +static void free_buffer_page(struct buffer_page *bpage) { - if (bpage->page) - free_page((unsigned long)bpage->page); + free_page((unsigned long)bpage->page); kfree(bpage); } @@ -811,7 +810,7 @@ rb_event_index(struct ring_buffer_event *event) return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); } -static inline int +static int rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { @@ -825,7 +824,7 @@ rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, rb_commit_index(cpu_buffer) == index; } -static inline void +static void rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { @@ -850,7 +849,7 @@ rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, local_set(&cpu_buffer->commit_page->page->commit, index); } -static inline void +static void rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) { /* @@ -896,7 +895,7 @@ static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->reader_page->read = 0; } -static inline void rb_inc_iter(struct ring_buffer_iter *iter) +static void rb_inc_iter(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; @@ -926,7 +925,7 @@ static inline void rb_inc_iter(struct ring_buffer_iter *iter) * and with this, we can determine what to place into the * data field. */ -static inline void +static void rb_update_event(struct ring_buffer_event *event, unsigned type, unsigned length) { @@ -964,7 +963,7 @@ rb_update_event(struct ring_buffer_event *event, } } -static inline unsigned rb_calculate_event_length(unsigned length) +static unsigned rb_calculate_event_length(unsigned length) { struct ring_buffer_event event; /* Used only for sizeof array */ @@ -1438,7 +1437,7 @@ int ring_buffer_write(struct ring_buffer *buffer, } EXPORT_SYMBOL_GPL(ring_buffer_write); -static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) +static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *reader = cpu_buffer->reader_page; struct buffer_page *head = cpu_buffer->head_page; -- cgit v1.2.3-70-g09d2 From 67d347245f76a149c45bffb1a10145d31d61d1da Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 9 Jan 2009 12:27:09 -0800 Subject: kernel/trace/ring_buffer.c: use DIV_ROUND_UP Instead of open-coding it. Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 9542990f515..4832ffa5d93 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -123,8 +123,7 @@ void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); #define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event)) -#define RB_ALIGNMENT_SHIFT 2 -#define RB_ALIGNMENT (1 << RB_ALIGNMENT_SHIFT) +#define RB_ALIGNMENT 4U #define RB_MAX_SMALL_DATA 28 enum { @@ -151,7 +150,7 @@ rb_event_length(struct ring_buffer_event *event) case RINGBUF_TYPE_DATA: if (event->len) - length = event->len << RB_ALIGNMENT_SHIFT; + length = event->len * RB_ALIGNMENT; else length = event->array[0]; return length + RB_EVNT_HDR_SIZE; @@ -937,15 +936,11 @@ rb_update_event(struct ring_buffer_event *event, break; case RINGBUF_TYPE_TIME_EXTEND: - event->len = - (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) - >> RB_ALIGNMENT_SHIFT; + event->len = DIV_ROUND_UP(RB_LEN_TIME_EXTEND, RB_ALIGNMENT); break; case RINGBUF_TYPE_TIME_STAMP: - event->len = - (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) - >> RB_ALIGNMENT_SHIFT; + event->len = DIV_ROUND_UP(RB_LEN_TIME_STAMP, RB_ALIGNMENT); break; case RINGBUF_TYPE_DATA: @@ -954,9 +949,7 @@ rb_update_event(struct ring_buffer_event *event, event->len = 0; event->array[0] = length; } else - event->len = - (length + (RB_ALIGNMENT-1)) - >> RB_ALIGNMENT_SHIFT; + event->len = DIV_ROUND_UP(length, RB_ALIGNMENT); break; default: BUG(); -- cgit v1.2.3-70-g09d2 From 6f3b34402e7282cde49dff395d7ea462bf33bf50 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Mon, 12 Jan 2009 11:06:18 +0800 Subject: ring_buffer: reset write when reserve buffer fail Impact: reset struct buffer_page.write when interrupt storm if struct buffer_page.write is not reset, any succedent committing will corrupted ring_buffer: static inline void rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) { ...... cpu_buffer->commit_page->commit = cpu_buffer->commit_page->write; ...... } when "if (RB_WARN_ON(cpu_buffer, next_page == reader_page))", ring_buffer is disabled, but some reserved buffers may haven't been committed. we need reset struct buffer_page.write. when "if (unlikely(next_page == cpu_buffer->commit_page))", ring_buffer is still available, we should not corrupt it. Signed-off-by: Lai Jiangshan Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 4832ffa5d93..0b9de5a3d69 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1017,12 +1017,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, } if (next_page == head_page) { - if (!(buffer->flags & RB_FL_OVERWRITE)) { - /* reset write */ - if (tail <= BUF_PAGE_SIZE) - local_set(&tail_page->write, tail); + if (!(buffer->flags & RB_FL_OVERWRITE)) goto out_unlock; - } /* tail_page has not moved yet? */ if (tail_page == cpu_buffer->tail_page) { @@ -1097,6 +1093,10 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, return event; out_unlock: + /* reset write */ + if (tail <= BUF_PAGE_SIZE) + local_set(&tail_page->write, tail); + __raw_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); return NULL; -- cgit v1.2.3-70-g09d2 From 97b17efe4537e11bf6669106cfe4ee2c5331b267 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 21 Jan 2009 15:24:56 -0500 Subject: ring-buffer: do not swap if recording is disabled If the ring buffer recording has been disabled. Do not let swapping of ring buffers occur. Simply return -EAGAIN. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 15 +++++++++++++++ kernel/trace/trace.c | 2 +- 2 files changed, 16 insertions(+), 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0b9de5a3d69..890020e28a3 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2266,9 +2266,24 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, if (buffer_a->pages != buffer_b->pages) return -EINVAL; + if (ring_buffer_flags != RB_BUFFERS_ON) + return -EAGAIN; + + if (atomic_read(&buffer_a->record_disabled)) + return -EAGAIN; + + if (atomic_read(&buffer_b->record_disabled)) + return -EAGAIN; + cpu_buffer_a = buffer_a->buffers[cpu]; cpu_buffer_b = buffer_b->buffers[cpu]; + if (atomic_read(&cpu_buffer_a->record_disabled)) + return -EAGAIN; + + if (atomic_read(&cpu_buffer_b->record_disabled)) + return -EAGAIN; + /* * We can't do a synchronize_sched here because this * function can be called in atomic context. diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 220c264e311..757ae6f7e64 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -415,7 +415,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) ftrace_enable_cpu(); - WARN_ON_ONCE(ret); + WARN_ON_ONCE(ret && ret != -EAGAIN); __update_max_tr(tr, tsk, cpu); __raw_spin_unlock(&ftrace_max_lock); -- cgit v1.2.3-70-g09d2 From 69507c06539332e6e49f83aa478844130233bece Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 21 Jan 2009 18:45:57 -0500 Subject: ring-buffer: reset timestamps when ring buffer is reset Impact: fix bad times of recent resets The ring buffer needs to reset its timestamps when reseting of the buffer, otherwise the timestamps are stale and might be used to calculate times in the buffer causing funny timestamps to appear. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 890020e28a3..7839280ffcd 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2166,6 +2166,9 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->overrun = 0; cpu_buffer->entries = 0; + + cpu_buffer->write_stamp = 0; + cpu_buffer->read_stamp = 0; } /** -- cgit v1.2.3-70-g09d2 From 0a9877514c4fed10a70720293b37213dd172ee3e Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Thu, 5 Feb 2009 16:12:56 -0200 Subject: ring_buffer: remove unused flags parameter MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Impact: API change, cleanup >From ring_buffer_{lock_reserve,unlock_commit}. $ codiff /tmp/vmlinux.before /tmp/vmlinux.after linux-2.6-tip/kernel/trace/trace.c: trace_vprintk | -14 trace_graph_return | -14 trace_graph_entry | -10 trace_function | -8 __ftrace_trace_stack | -8 ftrace_trace_userstack | -8 tracing_sched_switch_trace | -8 ftrace_trace_special | -12 tracing_sched_wakeup_trace | -8 9 functions changed, 90 bytes removed, diff: -90 linux-2.6-tip/block/blktrace.c: __blk_add_trace | -1 1 function changed, 1 bytes removed, diff: -1 /tmp/vmlinux.after: 10 functions changed, 91 bytes removed, diff: -91 Signed-off-by: Arnaldo Carvalho de Melo Acked-by: Frédéric Weisbecker Signed-off-by: Ingo Molnar --- block/blktrace.c | 8 +++--- include/linux/ring_buffer.h | 9 +++---- kernel/trace/kmemtrace.c | 12 +++------ kernel/trace/ring_buffer.c | 9 ++----- kernel/trace/trace.c | 56 ++++++++++++++-------------------------- kernel/trace/trace_boot.c | 12 +++------ kernel/trace/trace_branch.c | 7 +++-- kernel/trace/trace_hw_branches.c | 6 ++--- kernel/trace/trace_mmiotrace.c | 12 +++------ kernel/trace/trace_power.c | 12 +++------ 10 files changed, 51 insertions(+), 92 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/block/blktrace.c b/block/blktrace.c index d9d7146ee02..8e52f24cc8f 100644 --- a/block/blktrace.c +++ b/block/blktrace.c @@ -165,7 +165,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, struct task_struct *tsk = current; struct ring_buffer_event *event = NULL; struct blk_io_trace *t; - unsigned long flags; + unsigned long flags = 0; unsigned long *sequence; pid_t pid; int cpu, pc = 0; @@ -191,7 +191,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, tracing_record_cmdline(current); event = ring_buffer_lock_reserve(blk_tr->buffer, - sizeof(*t) + pdu_len, &flags); + sizeof(*t) + pdu_len); if (!event) return; @@ -241,11 +241,11 @@ record_it: memcpy((void *) t + sizeof(*t), pdu_data, pdu_len); if (blk_tr) { - ring_buffer_unlock_commit(blk_tr->buffer, event, flags); + ring_buffer_unlock_commit(blk_tr->buffer, event); if (pid != 0 && !(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC) && (trace_flags & TRACE_ITER_STACKTRACE) != 0) - __trace_stack(blk_tr, flags, 5, pc); + __trace_stack(blk_tr, 0, 5, pc); trace_wake_up(); return; } diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index b3b35966008..3110d92e7d8 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -74,13 +74,10 @@ void ring_buffer_free(struct ring_buffer *buffer); int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size); -struct ring_buffer_event * -ring_buffer_lock_reserve(struct ring_buffer *buffer, - unsigned long length, - unsigned long *flags); +struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer, + unsigned long length); int ring_buffer_unlock_commit(struct ring_buffer *buffer, - struct ring_buffer_event *event, - unsigned long flags); + struct ring_buffer_event *event); int ring_buffer_write(struct ring_buffer *buffer, unsigned long length, void *data); diff --git a/kernel/trace/kmemtrace.c b/kernel/trace/kmemtrace.c index f04c0625f1c..256749d1032 100644 --- a/kernel/trace/kmemtrace.c +++ b/kernel/trace/kmemtrace.c @@ -272,13 +272,11 @@ void kmemtrace_mark_alloc_node(enum kmemtrace_type_id type_id, struct ring_buffer_event *event; struct kmemtrace_alloc_entry *entry; struct trace_array *tr = kmemtrace_array; - unsigned long irq_flags; if (!kmem_tracing_enabled) return; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -292,7 +290,7 @@ void kmemtrace_mark_alloc_node(enum kmemtrace_type_id type_id, entry->gfp_flags = gfp_flags; entry->node = node; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); } @@ -305,13 +303,11 @@ void kmemtrace_mark_free(enum kmemtrace_type_id type_id, struct ring_buffer_event *event; struct kmemtrace_free_entry *entry; struct trace_array *tr = kmemtrace_array; - unsigned long irq_flags; if (!kmem_tracing_enabled) return; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -322,7 +318,7 @@ void kmemtrace_mark_free(enum kmemtrace_type_id type_id, entry->call_site = call_site; entry->ptr = ptr; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); } diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b36d7374cee..aee76b3eeed 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1257,7 +1257,6 @@ static DEFINE_PER_CPU(int, rb_need_resched); * ring_buffer_lock_reserve - reserve a part of the buffer * @buffer: the ring buffer to reserve from * @length: the length of the data to reserve (excluding event header) - * @flags: a pointer to save the interrupt flags * * Returns a reseverd event on the ring buffer to copy directly to. * The user of this interface will need to get the body to write into @@ -1270,9 +1269,7 @@ static DEFINE_PER_CPU(int, rb_need_resched); * If NULL is returned, then nothing has been allocated or locked. */ struct ring_buffer_event * -ring_buffer_lock_reserve(struct ring_buffer *buffer, - unsigned long length, - unsigned long *flags) +ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; @@ -1339,15 +1336,13 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, * ring_buffer_unlock_commit - commit a reserved * @buffer: The buffer to commit to * @event: The event pointer to commit. - * @flags: the interrupt flags received from ring_buffer_lock_reserve. * * This commits the data to the ring buffer, and releases any locks held. * * Must be paired with ring_buffer_lock_reserve. */ int ring_buffer_unlock_commit(struct ring_buffer *buffer, - struct ring_buffer_event *event, - unsigned long flags) + struct ring_buffer_event *event) { struct ring_buffer_per_cpu *cpu_buffer; int cpu = raw_smp_processor_id(); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 3536ef41575..eb453a238a6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -783,14 +783,12 @@ trace_function(struct trace_array *tr, { struct ring_buffer_event *event; struct ftrace_entry *entry; - unsigned long irq_flags; /* If we are reading the ring buffer, don't trace */ if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled)))) return; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -798,7 +796,7 @@ trace_function(struct trace_array *tr, entry->ent.type = TRACE_FN; entry->ip = ip; entry->parent_ip = parent_ip; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); } #ifdef CONFIG_FUNCTION_GRAPH_TRACER @@ -809,20 +807,18 @@ static void __trace_graph_entry(struct trace_array *tr, { struct ring_buffer_event *event; struct ftrace_graph_ent_entry *entry; - unsigned long irq_flags; if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled)))) return; - event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); tracing_generic_entry_update(&entry->ent, flags, pc); entry->ent.type = TRACE_GRAPH_ENT; entry->graph_ent = *trace; - ring_buffer_unlock_commit(global_trace.buffer, event, irq_flags); + ring_buffer_unlock_commit(global_trace.buffer, event); } static void __trace_graph_return(struct trace_array *tr, @@ -832,20 +828,18 @@ static void __trace_graph_return(struct trace_array *tr, { struct ring_buffer_event *event; struct ftrace_graph_ret_entry *entry; - unsigned long irq_flags; if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled)))) return; - event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); tracing_generic_entry_update(&entry->ent, flags, pc); entry->ent.type = TRACE_GRAPH_RET; entry->ret = *trace; - ring_buffer_unlock_commit(global_trace.buffer, event, irq_flags); + ring_buffer_unlock_commit(global_trace.buffer, event); } #endif @@ -866,10 +860,8 @@ static void __ftrace_trace_stack(struct trace_array *tr, struct ring_buffer_event *event; struct stack_entry *entry; struct stack_trace trace; - unsigned long irq_flags; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -884,7 +876,7 @@ static void __ftrace_trace_stack(struct trace_array *tr, trace.entries = entry->caller; save_stack_trace(&trace); - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); #endif } @@ -912,13 +904,11 @@ static void ftrace_trace_userstack(struct trace_array *tr, struct ring_buffer_event *event; struct userstack_entry *entry; struct stack_trace trace; - unsigned long irq_flags; if (!(trace_flags & TRACE_ITER_USERSTACKTRACE)) return; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -933,7 +923,7 @@ static void ftrace_trace_userstack(struct trace_array *tr, trace.entries = entry->caller; save_stack_trace_user(&trace); - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); #endif } @@ -950,10 +940,8 @@ ftrace_trace_special(void *__tr, struct ring_buffer_event *event; struct trace_array *tr = __tr; struct special_entry *entry; - unsigned long irq_flags; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -962,9 +950,9 @@ ftrace_trace_special(void *__tr, entry->arg1 = arg1; entry->arg2 = arg2; entry->arg3 = arg3; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); - ftrace_trace_stack(tr, irq_flags, 4, pc); - ftrace_trace_userstack(tr, irq_flags, pc); + ring_buffer_unlock_commit(tr->buffer, event); + ftrace_trace_stack(tr, 0, 4, pc); + ftrace_trace_userstack(tr, 0, pc); trace_wake_up(); } @@ -984,10 +972,8 @@ tracing_sched_switch_trace(struct trace_array *tr, { struct ring_buffer_event *event; struct ctx_switch_entry *entry; - unsigned long irq_flags; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -1000,7 +986,7 @@ tracing_sched_switch_trace(struct trace_array *tr, entry->next_prio = next->prio; entry->next_state = next->state; entry->next_cpu = task_cpu(next); - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); ftrace_trace_stack(tr, flags, 5, pc); ftrace_trace_userstack(tr, flags, pc); } @@ -1013,10 +999,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr, { struct ring_buffer_event *event; struct ctx_switch_entry *entry; - unsigned long irq_flags; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) return; entry = ring_buffer_event_data(event); @@ -1029,7 +1013,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr, entry->next_prio = wakee->prio; entry->next_state = wakee->state; entry->next_cpu = task_cpu(wakee); - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); ftrace_trace_stack(tr, flags, 6, pc); ftrace_trace_userstack(tr, flags, pc); @@ -2841,7 +2825,7 @@ int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args) trace_buf[len] = 0; size = sizeof(*entry) + len + 1; - event = ring_buffer_lock_reserve(tr->buffer, size, &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, size); if (!event) goto out_unlock; entry = ring_buffer_event_data(event); @@ -2852,7 +2836,7 @@ int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args) memcpy(&entry->buf, trace_buf, len); entry->buf[len] = 0; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); out_unlock: spin_unlock_irqrestore(&trace_buf_lock, irq_flags); diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c index 1f07895977a..4e08debf662 100644 --- a/kernel/trace/trace_boot.c +++ b/kernel/trace/trace_boot.c @@ -132,7 +132,6 @@ void trace_boot_call(struct boot_trace_call *bt, initcall_t fn) { struct ring_buffer_event *event; struct trace_boot_call *entry; - unsigned long irq_flags; struct trace_array *tr = boot_trace; if (!tr || !pre_initcalls_finished) @@ -144,15 +143,14 @@ void trace_boot_call(struct boot_trace_call *bt, initcall_t fn) sprint_symbol(bt->func, (unsigned long)fn); preempt_disable(); - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) goto out; entry = ring_buffer_event_data(event); tracing_generic_entry_update(&entry->ent, 0, 0); entry->ent.type = TRACE_BOOT_CALL; entry->boot_call = *bt; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); @@ -164,7 +162,6 @@ void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn) { struct ring_buffer_event *event; struct trace_boot_ret *entry; - unsigned long irq_flags; struct trace_array *tr = boot_trace; if (!tr || !pre_initcalls_finished) @@ -173,15 +170,14 @@ void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn) sprint_symbol(bt->func, (unsigned long)fn); preempt_disable(); - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) goto out; entry = ring_buffer_event_data(event); tracing_generic_entry_update(&entry->ent, 0, 0); entry->ent.type = TRACE_BOOT_RET; entry->boot_ret = *bt; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c index 027e8369061..770e52acfc1 100644 --- a/kernel/trace/trace_branch.c +++ b/kernel/trace/trace_branch.c @@ -33,7 +33,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) struct trace_array *tr = branch_tracer; struct ring_buffer_event *event; struct trace_branch *entry; - unsigned long flags, irq_flags; + unsigned long flags; int cpu, pc; const char *p; @@ -52,8 +52,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) goto out; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) goto out; @@ -75,7 +74,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) entry->line = f->line; entry->correct = val == expect; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); out: atomic_dec(&tr->data[cpu]->disabled); diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c index fff3545fc86..e720c001db2 100644 --- a/kernel/trace/trace_hw_branches.c +++ b/kernel/trace/trace_hw_branches.c @@ -175,7 +175,7 @@ void trace_hw_branch(u64 from, u64 to) struct trace_array *tr = hw_branch_trace; struct ring_buffer_event *event; struct hw_branch_entry *entry; - unsigned long irq1, irq2; + unsigned long irq1; int cpu; if (unlikely(!tr)) @@ -189,7 +189,7 @@ void trace_hw_branch(u64 from, u64 to) if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) goto out; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq2); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) goto out; entry = ring_buffer_event_data(event); @@ -198,7 +198,7 @@ void trace_hw_branch(u64 from, u64 to) entry->ent.cpu = cpu; entry->from = from; entry->to = to; - ring_buffer_unlock_commit(tr->buffer, event, irq2); + ring_buffer_unlock_commit(tr->buffer, event); out: atomic_dec(&tr->data[cpu]->disabled); diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c index ec78e244242..104ddebc11d 100644 --- a/kernel/trace/trace_mmiotrace.c +++ b/kernel/trace/trace_mmiotrace.c @@ -307,10 +307,8 @@ static void __trace_mmiotrace_rw(struct trace_array *tr, { struct ring_buffer_event *event; struct trace_mmiotrace_rw *entry; - unsigned long irq_flags; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) { atomic_inc(&dropped_count); return; @@ -319,7 +317,7 @@ static void __trace_mmiotrace_rw(struct trace_array *tr, tracing_generic_entry_update(&entry->ent, 0, preempt_count()); entry->ent.type = TRACE_MMIO_RW; entry->rw = *rw; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); } @@ -337,10 +335,8 @@ static void __trace_mmiotrace_map(struct trace_array *tr, { struct ring_buffer_event *event; struct trace_mmiotrace_map *entry; - unsigned long irq_flags; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) { atomic_inc(&dropped_count); return; @@ -349,7 +345,7 @@ static void __trace_mmiotrace_map(struct trace_array *tr, tracing_generic_entry_update(&entry->ent, 0, preempt_count()); entry->ent.type = TRACE_MMIO_MAP; entry->map = *map; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); } diff --git a/kernel/trace/trace_power.c b/kernel/trace/trace_power.c index faa6ab7a1f5..3b1a292d12d 100644 --- a/kernel/trace/trace_power.c +++ b/kernel/trace/trace_power.c @@ -115,7 +115,6 @@ void trace_power_end(struct power_trace *it) struct ring_buffer_event *event; struct trace_power *entry; struct trace_array_cpu *data; - unsigned long irq_flags; struct trace_array *tr = power_trace; if (!trace_power_enabled) @@ -125,15 +124,14 @@ void trace_power_end(struct power_trace *it) it->end = ktime_get(); data = tr->data[smp_processor_id()]; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) goto out; entry = ring_buffer_event_data(event); tracing_generic_entry_update(&entry->ent, 0, 0); entry->ent.type = TRACE_POWER; entry->state_data = *it; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); @@ -148,7 +146,6 @@ void trace_power_mark(struct power_trace *it, unsigned int type, struct ring_buffer_event *event; struct trace_power *entry; struct trace_array_cpu *data; - unsigned long irq_flags; struct trace_array *tr = power_trace; if (!trace_power_enabled) @@ -162,15 +159,14 @@ void trace_power_mark(struct power_trace *it, unsigned int type, it->end = it->stamp; data = tr->data[smp_processor_id()]; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), - &irq_flags); + event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry)); if (!event) goto out; entry = ring_buffer_event_data(event); tracing_generic_entry_update(&entry->ent, 0, 0); entry->ent.type = TRACE_POWER; entry->state_data = *it; - ring_buffer_unlock_commit(tr->buffer, event, irq_flags); + ring_buffer_unlock_commit(tr->buffer, event); trace_wake_up(); -- cgit v1.2.3-70-g09d2 From 78d904b46a72fcf15ea6a39672bbef92953876b5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 5 Feb 2009 18:43:07 -0500 Subject: ring-buffer: add NMI protection for spinlocks Impact: prevent deadlock in NMI The ring buffers are not yet totally lockless with writing to the buffer. When a writer crosses a page, it grabs a per cpu spinlock to protect against a reader. The spinlocks taken by a writer are not to protect against other writers, since a writer can only write to its own per cpu buffer. The spinlocks protect against readers that can touch any cpu buffer. The writers are made to be reentrant with the spinlocks disabling interrupts. The problem arises when an NMI writes to the buffer, and that write crosses a page boundary. If it grabs a spinlock, it can be racing with another writer (since disabling interrupts does not protect against NMIs) or with a reader on the same CPU. Luckily, most of the users are not reentrant and protects against this issue. But if a user of the ring buffer becomes reentrant (which is what the ring buffers do allow), if the NMI also writes to the ring buffer then we risk the chance of a deadlock. This patch moves the ftrace_nmi_enter called by nmi_enter() to the ring buffer code. It replaces the current ftrace_nmi_enter that is used by arch specific code to arch_ftrace_nmi_enter and updates the Kconfig to handle it. When an NMI is called, it will set a per cpu variable in the ring buffer code and will clear it when the NMI exits. If a write to the ring buffer crosses page boundaries inside an NMI, a trylock is used on the spin lock instead. If the spinlock fails to be acquired, then the entry is discarded. This bug appeared in the ftrace work in the RT tree, where event tracing is reentrant. This workaround solved the deadlocks that appeared there. Signed-off-by: Steven Rostedt --- arch/x86/Kconfig | 1 + arch/x86/kernel/ftrace.c | 8 ++++---- include/linux/ftrace_irq.h | 10 +++++++++- kernel/trace/Kconfig | 8 ++++++++ kernel/trace/ring_buffer.c | 48 ++++++++++++++++++++++++++++++++++++++++++++-- 5 files changed, 68 insertions(+), 7 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 73f7fe8fd4d..a6be725cb04 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -34,6 +34,7 @@ config X86 select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACE_MCOUNT_TEST + select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE || FUNCTION_GRAPH_TRACER select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64) select HAVE_ARCH_KGDB if !X86_VOYAGER select HAVE_ARCH_TRACEHOOK diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 4d33224c055..4c683587055 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -113,7 +113,7 @@ static void ftrace_mod_code(void) MCOUNT_INSN_SIZE); } -void ftrace_nmi_enter(void) +void arch_ftrace_nmi_enter(void) { atomic_inc(&in_nmi); /* Must have in_nmi seen before reading write flag */ @@ -124,7 +124,7 @@ void ftrace_nmi_enter(void) } } -void ftrace_nmi_exit(void) +void arch_ftrace_nmi_exit(void) { /* Finish all executions before clearing in_nmi */ smp_wmb(); @@ -376,12 +376,12 @@ int ftrace_disable_ftrace_graph_caller(void) */ static atomic_t in_nmi; -void ftrace_nmi_enter(void) +void arch_ftrace_nmi_enter(void) { atomic_inc(&in_nmi); } -void ftrace_nmi_exit(void) +void arch_ftrace_nmi_exit(void) { atomic_dec(&in_nmi); } diff --git a/include/linux/ftrace_irq.h b/include/linux/ftrace_irq.h index 366a054d0b0..29de6779a96 100644 --- a/include/linux/ftrace_irq.h +++ b/include/linux/ftrace_irq.h @@ -2,7 +2,15 @@ #define _LINUX_FTRACE_IRQ_H -#if defined(CONFIG_DYNAMIC_FTRACE) || defined(CONFIG_FUNCTION_GRAPH_TRACER) +#ifdef CONFIG_FTRACE_NMI_ENTER +extern void arch_ftrace_nmi_enter(void); +extern void arch_ftrace_nmi_exit(void); +#else +static inline void arch_ftrace_nmi_enter(void) { } +static inline void arch_ftrace_nmi_exit(void) { } +#endif + +#ifdef CONFIG_RING_BUFFER extern void ftrace_nmi_enter(void); extern void ftrace_nmi_exit(void); #else diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 28f2644484d..25131a5d5e4 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -9,6 +9,9 @@ config USER_STACKTRACE_SUPPORT config NOP_TRACER bool +config HAVE_FTRACE_NMI_ENTER + bool + config HAVE_FUNCTION_TRACER bool @@ -37,6 +40,11 @@ config TRACER_MAX_TRACE config RING_BUFFER bool +config FTRACE_NMI_ENTER + bool + depends on HAVE_FTRACE_NMI_ENTER + default y + config TRACING bool select DEBUG_FS diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b36d7374cee..a60a6a852f4 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4,6 +4,7 @@ * Copyright (C) 2008 Steven Rostedt */ #include +#include #include #include #include @@ -18,6 +19,35 @@ #include "trace.h" +/* + * Since the write to the buffer is still not fully lockless, + * we must be careful with NMIs. The locks in the writers + * are taken when a write crosses to a new page. The locks + * protect against races with the readers (this will soon + * be fixed with a lockless solution). + * + * Because we can not protect against NMIs, and we want to + * keep traces reentrant, we need to manage what happens + * when we are in an NMI. + */ +static DEFINE_PER_CPU(int, rb_in_nmi); + +void ftrace_nmi_enter(void) +{ + __get_cpu_var(rb_in_nmi)++; + /* call arch specific handler too */ + arch_ftrace_nmi_enter(); +} + +void ftrace_nmi_exit(void) +{ + arch_ftrace_nmi_exit(); + __get_cpu_var(rb_in_nmi)--; + /* NMIs are not recursive */ + WARN_ON_ONCE(__get_cpu_var(rb_in_nmi)); +} + + /* * A fast way to enable or disable all ring buffers is to * call tracing_on or tracing_off. Turning off the ring buffers @@ -982,6 +1012,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer *buffer = cpu_buffer->buffer; struct ring_buffer_event *event; unsigned long flags; + bool lock_taken = false; commit_page = cpu_buffer->commit_page; /* we just need to protect against interrupts */ @@ -995,7 +1026,19 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *next_page = tail_page; local_irq_save(flags); - __raw_spin_lock(&cpu_buffer->lock); + /* + * NMIs can happen after we take the lock. + * If we are in an NMI, only take the lock + * if it is not already taken. Otherwise + * simply fail. + */ + if (unlikely(__get_cpu_var(rb_in_nmi))) { + if (!__raw_spin_trylock(&cpu_buffer->lock)) + goto out_unlock; + } else + __raw_spin_lock(&cpu_buffer->lock); + + lock_taken = true; rb_inc_page(cpu_buffer, &next_page); @@ -1097,7 +1140,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, if (tail <= BUF_PAGE_SIZE) local_set(&tail_page->write, tail); - __raw_spin_unlock(&cpu_buffer->lock); + if (likely(lock_taken)) + __raw_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); return NULL; } -- cgit v1.2.3-70-g09d2 From a81bd80a0b0a405dc0483e2c428332d69da2c79f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 6 Feb 2009 01:45:16 -0500 Subject: ring-buffer: use generic version of in_nmi Impact: clean up Now that a generic in_nmi is available, this patch removes the special code in the ring_buffer and implements the in_nmi generic version instead. With this change, I was also able to rename the "arch_ftrace_nmi_enter" back to "ftrace_nmi_enter" and remove the code from the ring buffer. Signed-off-by: Steven Rostedt --- arch/x86/kernel/ftrace.c | 4 ++-- include/linux/ftrace_irq.h | 8 -------- kernel/trace/ring_buffer.c | 43 +++++++++++++------------------------------ 3 files changed, 15 insertions(+), 40 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 918073c6681..d74d75e0952 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -113,7 +113,7 @@ static void ftrace_mod_code(void) MCOUNT_INSN_SIZE); } -void arch_ftrace_nmi_enter(void) +void ftrace_nmi_enter(void) { atomic_inc(&nmi_running); /* Must have nmi_running seen before reading write flag */ @@ -124,7 +124,7 @@ void arch_ftrace_nmi_enter(void) } } -void arch_ftrace_nmi_exit(void) +void ftrace_nmi_exit(void) { /* Finish all executions before clearing nmi_running */ smp_wmb(); diff --git a/include/linux/ftrace_irq.h b/include/linux/ftrace_irq.h index 29de6779a96..dca7bf8cffe 100644 --- a/include/linux/ftrace_irq.h +++ b/include/linux/ftrace_irq.h @@ -3,14 +3,6 @@ #ifdef CONFIG_FTRACE_NMI_ENTER -extern void arch_ftrace_nmi_enter(void); -extern void arch_ftrace_nmi_exit(void); -#else -static inline void arch_ftrace_nmi_enter(void) { } -static inline void arch_ftrace_nmi_exit(void) { } -#endif - -#ifdef CONFIG_RING_BUFFER extern void ftrace_nmi_enter(void); extern void ftrace_nmi_exit(void); #else diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index a60a6a852f4..5ee344417cd 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -19,35 +20,6 @@ #include "trace.h" -/* - * Since the write to the buffer is still not fully lockless, - * we must be careful with NMIs. The locks in the writers - * are taken when a write crosses to a new page. The locks - * protect against races with the readers (this will soon - * be fixed with a lockless solution). - * - * Because we can not protect against NMIs, and we want to - * keep traces reentrant, we need to manage what happens - * when we are in an NMI. - */ -static DEFINE_PER_CPU(int, rb_in_nmi); - -void ftrace_nmi_enter(void) -{ - __get_cpu_var(rb_in_nmi)++; - /* call arch specific handler too */ - arch_ftrace_nmi_enter(); -} - -void ftrace_nmi_exit(void) -{ - arch_ftrace_nmi_exit(); - __get_cpu_var(rb_in_nmi)--; - /* NMIs are not recursive */ - WARN_ON_ONCE(__get_cpu_var(rb_in_nmi)); -} - - /* * A fast way to enable or disable all ring buffers is to * call tracing_on or tracing_off. Turning off the ring buffers @@ -1027,12 +999,23 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, local_irq_save(flags); /* + * Since the write to the buffer is still not + * fully lockless, we must be careful with NMIs. + * The locks in the writers are taken when a write + * crosses to a new page. The locks protect against + * races with the readers (this will soon be fixed + * with a lockless solution). + * + * Because we can not protect against NMIs, and we + * want to keep traces reentrant, we need to manage + * what happens when we are in an NMI. + * * NMIs can happen after we take the lock. * If we are in an NMI, only take the lock * if it is not already taken. Otherwise * simply fail. */ - if (unlikely(__get_cpu_var(rb_in_nmi))) { + if (unlikely(in_nmi())) { if (!__raw_spin_trylock(&cpu_buffer->lock)) goto out_unlock; } else -- cgit v1.2.3-70-g09d2 From b85fa01ed958ca59523a2db3c2ee647b98745d6a Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Mon, 9 Feb 2009 14:21:14 +0800 Subject: ring_buffer: fix typing mistake Impact: Fix bug I found several very very curious line. It's so curious that it may be brought by typing mistake. When (cpu_buffer->reader_page == cpu_buffer->commit_page): 1) We haven't copied it for bpage is changed: bpage = cpu_buffer->reader_page->page; memcpy(bpage->data, cpu_buffer->reader_page->page->data + read ... ) 2) We need update cpu_buffer->reader_page->read, but "cpu_buffer->reader_page += read;" is not right. [ This bug was a typo. The commit->reader_page is a page pointer and not an index into the page. The line should have been commit->reader_page->read += read. The other changes by Lai are nice clean ups to the code. - SDR ] Signed-off-by: Lai Jiangshan Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 53ba3a6d16d..eca28272083 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2406,7 +2406,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) * to swap with a page in the ring buffer. * * for example: - * rpage = ring_buffer_alloc_page(buffer); + * rpage = ring_buffer_alloc_read_page(buffer); * if (!rpage) * return error; * ret = ring_buffer_read_page(buffer, &rpage, cpu, 0); @@ -2461,18 +2461,17 @@ int ring_buffer_read_page(struct ring_buffer *buffer, */ if (cpu_buffer->reader_page == cpu_buffer->commit_page) { unsigned int read = cpu_buffer->reader_page->read; + unsigned int commit = rb_page_commit(cpu_buffer->reader_page); if (full) goto out; /* The writer is still on the reader page, we must copy */ - bpage = cpu_buffer->reader_page->page; memcpy(bpage->data, cpu_buffer->reader_page->page->data + read, - local_read(&bpage->commit) - read); + commit - read); /* consume what was read */ - cpu_buffer->reader_page += read; - + cpu_buffer->reader_page->read = commit; } else { /* swap the pages */ rb_init_page(bpage); -- cgit v1.2.3-70-g09d2 From 667d24125839b6f3363d8177d7ed9fab8a40e45f Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Mon, 9 Feb 2009 14:21:17 +0800 Subject: ring_buffer: fix ring_buffer_read_page() Impact: change API and init bpage when copy ring_buffer_read_page()/rb_remove_entries() may be called for a partially consumed page. Add a parameter for rb_remove_entries() and make it update cpu_buffer->entries correctly for partially consumed pages. ring_buffer_read_page() now returns the offset to the next event. Init the bpage's time_stamp when return value is 0. Signed-off-by: Lai Jiangshan Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index eca28272083..10d202ea06f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2332,13 +2332,14 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer, - struct buffer_data_page *bpage) + struct buffer_data_page *bpage, + unsigned int offset) { struct ring_buffer_event *event; unsigned long head; __raw_spin_lock(&cpu_buffer->lock); - for (head = 0; head < local_read(&bpage->commit); + for (head = offset; head < local_read(&bpage->commit); head += rb_event_length(event)) { event = __rb_data_page_index(bpage, head); @@ -2410,8 +2411,8 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) * if (!rpage) * return error; * ret = ring_buffer_read_page(buffer, &rpage, cpu, 0); - * if (ret) - * process_page(rpage); + * if (ret >= 0) + * process_page(rpage, ret); * * When @full is set, the function will not return true unless * the writer is off the reader page. @@ -2422,8 +2423,8 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) * responsible for that. * * Returns: - * 1 if data has been transferred - * 0 if no data has been transferred. + * >=0 if data has been transferred, returns the offset of consumed data. + * <0 if no data has been transferred. */ int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page, int cpu, int full) @@ -2432,7 +2433,8 @@ int ring_buffer_read_page(struct ring_buffer *buffer, struct ring_buffer_event *event; struct buffer_data_page *bpage; unsigned long flags; - int ret = 0; + unsigned int read; + int ret = -1; if (!data_page) return 0; @@ -2454,24 +2456,29 @@ int ring_buffer_read_page(struct ring_buffer *buffer, /* check for data */ if (!local_read(&cpu_buffer->reader_page->page->commit)) goto out; + + read = cpu_buffer->reader_page->read; /* * If the writer is already off of the read page, then simply * switch the read page with the given page. Otherwise * we need to copy the data from the reader to the writer. */ if (cpu_buffer->reader_page == cpu_buffer->commit_page) { - unsigned int read = cpu_buffer->reader_page->read; unsigned int commit = rb_page_commit(cpu_buffer->reader_page); + struct buffer_data_page *rpage = cpu_buffer->reader_page->page; if (full) goto out; /* The writer is still on the reader page, we must copy */ - memcpy(bpage->data, - cpu_buffer->reader_page->page->data + read, - commit - read); + memcpy(bpage->data + read, rpage->data + read, commit - read); /* consume what was read */ cpu_buffer->reader_page->read = commit; + + /* update bpage */ + local_set(&bpage->commit, commit); + if (!read) + bpage->time_stamp = rpage->time_stamp; } else { /* swap the pages */ rb_init_page(bpage); @@ -2480,10 +2487,10 @@ int ring_buffer_read_page(struct ring_buffer *buffer, cpu_buffer->reader_page->read = 0; *data_page = bpage; } - ret = 1; + ret = read; /* update the entry counter */ - rb_remove_entries(cpu_buffer, bpage); + rb_remove_entries(cpu_buffer, bpage, read); out: spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); -- cgit v1.2.3-70-g09d2 From c3706f005c3aaf570e71f0f083fdbb59a5a9fa2e Mon Sep 17 00:00:00 2001 From: Wenji Huang Date: Tue, 10 Feb 2009 01:03:18 -0500 Subject: tracing: fix typos in comments Impact: clean up. Fix typos in the comments. Signed-off-by: Wenji Huang Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 2 +- kernel/trace/ring_buffer.c | 8 ++++---- kernel/trace/trace.c | 2 +- kernel/trace/trace_hw_branches.c | 2 +- 4 files changed, 7 insertions(+), 7 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 3c103d636da..8e6646a54ac 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -8,7 +8,7 @@ struct ring_buffer; struct ring_buffer_iter; /* - * Don't reference this struct directly, use functions below. + * Don't refer to this struct directly, use functions below. */ struct ring_buffer_event { u32 type:2, len:3, time_delta:27; diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 10d202ea06f..fa64e1f003e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -91,7 +91,7 @@ EXPORT_SYMBOL_GPL(tracing_off); * tracing_off_permanent - permanently disable ring buffers * * This function, once called, will disable all ring buffers - * permanenty. + * permanently. */ void tracing_off_permanent(void) { @@ -210,7 +210,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); struct buffer_data_page { u64 time_stamp; /* page time stamp */ - local_t commit; /* write commited index */ + local_t commit; /* write committed index */ unsigned char data[]; /* data of buffer page */ }; @@ -260,7 +260,7 @@ struct ring_buffer_per_cpu { struct list_head pages; struct buffer_page *head_page; /* read from head */ struct buffer_page *tail_page; /* write to tail */ - struct buffer_page *commit_page; /* commited pages */ + struct buffer_page *commit_page; /* committed pages */ struct buffer_page *reader_page; unsigned long overrun; unsigned long entries; @@ -303,7 +303,7 @@ struct ring_buffer_iter { * check_pages - integrity check of buffer pages * @cpu_buffer: CPU buffer with pages to test * - * As a safty measure we check to make sure the data pages have not + * As a safety measure we check to make sure the data pages have not * been corrupted. */ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d89821283b4..d7c175a442d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1963,7 +1963,7 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf, struct tracer_opt *trace_opts = current_trace->flags->opts; - /* calulate max size */ + /* calculate max size */ for (i = 0; trace_options[i]; i++) { len += strlen(trace_options[i]); len += 3; /* "no" and space */ diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c index e3e7db61c06..0794dd33f27 100644 --- a/kernel/trace/trace_hw_branches.c +++ b/kernel/trace/trace_hw_branches.c @@ -75,7 +75,7 @@ static void bts_trace_start(struct trace_array *tr) } /* - * Start tracing on the current cpu. + * Stop tracing on the current cpu. * The argument is ignored. * * pre: bts_tracer_mutex must be locked. -- cgit v1.2.3-70-g09d2 From 5e39841c45cf5e6ea930ede1b0303309e03037a2 Mon Sep 17 00:00:00 2001 From: Hannes Eder Date: Tue, 10 Feb 2009 19:44:34 +0100 Subject: tracing: fix sparse warnings: fix (un-)signedness Fix these sparse warnings: kernel/trace/ring_buffer.c:70:37: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:84:39: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:96:43: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:2475:13: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:2475:13: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:2478:42: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:2478:42: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:2500:40: warning: incorrect type in argument 3 (different signedness) kernel/trace/ring_buffer.c:2505:44: warning: incorrect type in argument 2 (different signedness) kernel/trace/ring_buffer.c:2507:46: warning: incorrect type in argument 2 (different signedness) kernel/trace/trace.c:2130:40: warning: incorrect type in argument 3 (different signedness) kernel/trace/trace.c:2280:40: warning: incorrect type in argument 3 (different signedness) Signed-off-by: Hannes Eder Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 8 ++++---- kernel/trace/trace.c | 6 +++--- 2 files changed, 7 insertions(+), 7 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index fa64e1f003e..dc18b5b9ccb 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -59,7 +59,7 @@ enum { RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, }; -static long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; +static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; /** * tracing_on - enable all tracing buffers @@ -2501,7 +2501,7 @@ static ssize_t rb_simple_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { - long *p = filp->private_data; + unsigned long *p = filp->private_data; char buf[64]; int r; @@ -2517,9 +2517,9 @@ static ssize_t rb_simple_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { - long *p = filp->private_data; + unsigned long *p = filp->private_data; char buf[64]; - long val; + unsigned long val; int ret; if (cnt >= sizeof(buf)) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c157ba70f30..e2434990277 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2147,7 +2147,7 @@ tracing_ctrl_write(struct file *filp, const char __user *ubuf, { struct trace_array *tr = filp->private_data; char buf[64]; - long val; + unsigned long val; int ret; if (cnt >= sizeof(buf)) @@ -2295,9 +2295,9 @@ static ssize_t tracing_max_lat_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { - long *ptr = filp->private_data; + unsigned long *ptr = filp->private_data; char buf[64]; - long val; + unsigned long val; int ret; if (cnt >= sizeof(buf)) -- cgit v1.2.3-70-g09d2 From 00f62f614bb713027b9296068d1879fbca511eb7 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 9 Feb 2009 17:04:06 -0200 Subject: ring_buffer: pahole struct ring_buffer While fixing some bugs in pahole (built-in.o files were not being processed due to relocation problems) I found out about these packable structures: $ pahole --packable kernel/trace/ring_buffer.o | grep ring ring_buffer 72 64 8 ring_buffer_per_cpu 112 104 8 If we take a look at the current layout of struct ring_buffer we can see that we have two 4 bytes holes. $ pahole -C ring_buffer kernel/trace/ring_buffer.o struct ring_buffer { unsigned int pages; /* 0 4 */ unsigned int flags; /* 4 4 */ int cpus; /* 8 4 */ /* XXX 4 bytes hole, try to pack */ cpumask_var_t cpumask; /* 16 8 */ atomic_t record_disabled; /* 24 4 */ /* XXX 4 bytes hole, try to pack */ struct mutex mutex; /* 32 32 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct ring_buffer_per_cpu * * buffers; /* 64 8 */ /* size: 72, cachelines: 2, members: 7 */ /* sum members: 64, holes: 2, sum holes: 8 */ /* last cacheline: 8 bytes */ }; So, if I ask pahole to reorganize it: $ pahole -C ring_buffer --reorganize kernel/trace/ring_buffer.o struct ring_buffer { unsigned int pages; /* 0 4 */ unsigned int flags; /* 4 4 */ int cpus; /* 8 4 */ atomic_t record_disabled; /* 12 4 */ cpumask_var_t cpumask; /* 16 8 */ struct mutex mutex; /* 24 32 */ struct ring_buffer_per_cpu * * buffers; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ /* size: 64, cachelines: 1, members: 7 */ }; /* saved 8 bytes and 1 cacheline! */ We get it using just one 64 bytes cacheline. To see what it did: $ pahole -C ring_buffer --reorganize --show_reorg_steps \ kernel/trace/ring_buffer.o | grep \/ /* Moving 'record_disabled' from after 'cpumask' to after 'cpus' */ Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 53ba3a6d16d..27ef3bf13ed 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -273,8 +273,8 @@ struct ring_buffer { unsigned pages; unsigned flags; int cpus; - cpumask_var_t cpumask; atomic_t record_disabled; + cpumask_var_t cpumask; struct mutex mutex; -- cgit v1.2.3-70-g09d2 From 45141d4667d208421ca787a3301542b6a5e0b112 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 12 Feb 2009 13:19:48 -0500 Subject: ring-buffer: rename label out_unlock to out_reset Impact: clean up While reviewing the ring buffer code, I thougth I saw a bug with if (!__raw_spin_trylock(&cpu_buffer->lock)) goto out_unlock; But I forgot that we use a variable "lock_taken" that is set if the spinlock is taken, and only unlock it if that variable is set. To avoid further confusion from other reviewers, this patch renames the label out_unlock with out_reset, which is the more appropriate name. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index dc18b5b9ccb..f39d7e9a430 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1017,7 +1017,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, */ if (unlikely(in_nmi())) { if (!__raw_spin_trylock(&cpu_buffer->lock)) - goto out_unlock; + goto out_reset; } else __raw_spin_lock(&cpu_buffer->lock); @@ -1030,7 +1030,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, /* we grabbed the lock before incrementing */ if (RB_WARN_ON(cpu_buffer, next_page == reader_page)) - goto out_unlock; + goto out_reset; /* * If for some reason, we had an interrupt storm that made @@ -1039,12 +1039,12 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, */ if (unlikely(next_page == commit_page)) { WARN_ON_ONCE(1); - goto out_unlock; + goto out_reset; } if (next_page == head_page) { if (!(buffer->flags & RB_FL_OVERWRITE)) - goto out_unlock; + goto out_reset; /* tail_page has not moved yet? */ if (tail_page == cpu_buffer->tail_page) { @@ -1118,7 +1118,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, return event; - out_unlock: + out_reset: /* reset write */ if (tail <= BUF_PAGE_SIZE) local_set(&tail_page->write, tail); -- cgit v1.2.3-70-g09d2 From 988ae9d6b2bc3ebdc1a488490250a6812f85e9d4 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Sat, 14 Feb 2009 19:17:02 -0500 Subject: ring-buffer: add tracing_is_on to test if ring buffer is enabled This patch adds the tracing_is_on() interface to tell if the ring buffer is turned on or not. Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 2 ++ kernel/trace/ring_buffer.c | 9 +++++++++ 2 files changed, 11 insertions(+) (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 8e6646a54ac..f5e793d69bd 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -128,10 +128,12 @@ void ring_buffer_normalize_time_stamp(int cpu, u64 *ts); void tracing_on(void); void tracing_off(void); void tracing_off_permanent(void); +int tracing_is_on(void); #else static inline void tracing_on(void) { } static inline void tracing_off(void) { } static inline void tracing_off_permanent(void) { } +static inline int tracing_is_on(void) { return 0; } #endif void *ring_buffer_alloc_read_page(struct ring_buffer *buffer); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2b4626ce95d..8f19f1aa42b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -98,6 +98,15 @@ void tracing_off_permanent(void) set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); } +/** + * tracing_is_on - show state of ring buffers enabled + */ +int tracing_is_on(void) +{ + return ring_buffer_flags == RB_BUFFERS_ON; +} +EXPORT_SYMBOL_GPL(tracing_is_on); + #include "trace.h" /* Up this if you want to test the TIME_EXTENTS and normalization */ -- cgit v1.2.3-70-g09d2 From 14131f2f98ac350ee9e73faed916d2238a8b6a0d Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 26 Feb 2009 18:47:11 +0100 Subject: tracing: implement trace_clock_*() APIs Impact: implement new tracing timestamp APIs Add three trace clock variants, with differing scalability/precision tradeoffs: - local: CPU-local trace clock - medium: scalable global clock with some jitter - global: globally monotonic, serialized clock Make the ring-buffer use the local trace clock internally. Acked-by: Peter Zijlstra Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar --- include/linux/trace_clock.h | 19 +++++++++ kernel/trace/Makefile | 1 + kernel/trace/ring_buffer.c | 5 +-- kernel/trace/trace_clock.c | 101 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 123 insertions(+), 3 deletions(-) create mode 100644 include/linux/trace_clock.h create mode 100644 kernel/trace/trace_clock.c (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/trace_clock.h b/include/linux/trace_clock.h new file mode 100644 index 00000000000..7a813038408 --- /dev/null +++ b/include/linux/trace_clock.h @@ -0,0 +1,19 @@ +#ifndef _LINUX_TRACE_CLOCK_H +#define _LINUX_TRACE_CLOCK_H + +/* + * 3 trace clock variants, with differing scalability/precision + * tradeoffs: + * + * - local: CPU-local trace clock + * - medium: scalable global clock with some jitter + * - global: globally monotonic, serialized clock + */ +#include +#include + +extern u64 notrace trace_clock_local(void); +extern u64 notrace trace_clock(void); +extern u64 notrace trace_clock_global(void); + +#endif /* _LINUX_TRACE_CLOCK_H */ diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 664b6c0dc75..c931fe0560c 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -19,6 +19,7 @@ obj-$(CONFIG_FUNCTION_TRACER) += libftrace.o obj-$(CONFIG_RING_BUFFER) += ring_buffer.o obj-$(CONFIG_TRACING) += trace.o +obj-$(CONFIG_TRACING) += trace_clock.o obj-$(CONFIG_TRACING) += trace_output.o obj-$(CONFIG_TRACING) += trace_stat.o obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8f19f1aa42b..a8c275c01e8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4,6 +4,7 @@ * Copyright (C) 2008 Steven Rostedt */ #include +#include #include #include #include @@ -12,7 +13,6 @@ #include #include #include -#include /* used for sched_clock() (for now) */ #include #include #include @@ -112,14 +112,13 @@ EXPORT_SYMBOL_GPL(tracing_is_on); /* Up this if you want to test the TIME_EXTENTS and normalization */ #define DEBUG_SHIFT 0 -/* FIXME!!! */ u64 ring_buffer_time_stamp(int cpu) { u64 time; preempt_disable_notrace(); /* shift to debug/test normalization and TIME_EXTENTS */ - time = sched_clock() << DEBUG_SHIFT; + time = trace_clock_local() << DEBUG_SHIFT; preempt_enable_no_resched_notrace(); return time; diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c new file mode 100644 index 00000000000..2d4953f9356 --- /dev/null +++ b/kernel/trace/trace_clock.c @@ -0,0 +1,101 @@ +/* + * tracing clocks + * + * Copyright (C) 2009 Red Hat, Inc., Ingo Molnar + * + * Implements 3 trace clock variants, with differing scalability/precision + * tradeoffs: + * + * - local: CPU-local trace clock + * - medium: scalable global clock with some jitter + * - global: globally monotonic, serialized clock + * + * Tracer plugins will chose a default from these clocks. + */ +#include +#include +#include +#include +#include +#include + +/* + * trace_clock_local(): the simplest and least coherent tracing clock. + * + * Useful for tracing that does not cross to other CPUs nor + * does it go through idle events. + */ +u64 notrace trace_clock_local(void) +{ + /* + * sched_clock() is an architecture implemented, fast, scalable, + * lockless clock. It is not guaranteed to be coherent across + * CPUs, nor across CPU idle events. + */ + return sched_clock(); +} + +/* + * trace_clock(): 'inbetween' trace clock. Not completely serialized, + * but not completely incorrect when crossing CPUs either. + * + * This is based on cpu_clock(), which will allow at most ~1 jiffy of + * jitter between CPUs. So it's a pretty scalable clock, but there + * can be offsets in the trace data. + */ +u64 notrace trace_clock(void) +{ + return cpu_clock(raw_smp_processor_id()); +} + + +/* + * trace_clock_global(): special globally coherent trace clock + * + * It has higher overhead than the other trace clocks but is still + * an order of magnitude faster than GTOD derived hardware clocks. + * + * Used by plugins that need globally coherent timestamps. + */ + +static u64 prev_trace_clock_time; + +static raw_spinlock_t trace_clock_lock ____cacheline_aligned_in_smp = + (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; + +u64 notrace trace_clock_global(void) +{ + unsigned long flags; + int this_cpu; + u64 now; + + raw_local_irq_save(flags); + + this_cpu = raw_smp_processor_id(); + now = cpu_clock(this_cpu); + /* + * If in an NMI context then dont risk lockups and return the + * cpu_clock() time: + */ + if (unlikely(in_nmi())) + goto out; + + __raw_spin_lock(&trace_clock_lock); + + /* + * TODO: if this happens often then maybe we should reset + * my_scd->clock to prev_trace_clock_time+1, to make sure + * we start ticking with the local clock from now on? + */ + if ((s64)(now - prev_trace_clock_time) < 0) + now = prev_trace_clock_time + 1; + + prev_trace_clock_time = now; + + __raw_spin_unlock(&trace_clock_lock); + + out: + raw_local_irq_restore(flags); + + return now; +} -- cgit v1.2.3-70-g09d2 From 41be4da4e85e58520b934040966a6ae919c66c2d Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 2 Mar 2009 20:56:48 -0500 Subject: ring-buffer: reset write field for ring_buffer_read_page Impact: fix ring_buffer_read_page After a page is swapped into the ring buffer, the write field must also be reset. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index a8c275c01e8..9baad7ee4b3 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2492,6 +2492,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, rb_init_page(bpage); bpage = cpu_buffer->reader_page->page; cpu_buffer->reader_page->page = *data_page; + local_set(&cpu_buffer->reader_page->write, 0); cpu_buffer->reader_page->read = 0; *data_page = bpage; } -- cgit v1.2.3-70-g09d2 From ef7a4a161472b952941bf78855a9cd95703c024e Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 3 Mar 2009 00:27:49 -0500 Subject: ring-buffer: fix ring_buffer_read_page The ring_buffer_read_page was broken if it were to only copy part of the page. This patch fixes that up as well as adds a parameter to allow a length field, in order to only copy part of the buffer page. Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 7 +++- kernel/trace/ring_buffer.c | 92 +++++++++++++++++++++++++++++---------------- 2 files changed, 64 insertions(+), 35 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index f5e793d69bd..79fcbc4b09d 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -121,6 +121,9 @@ unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu); u64 ring_buffer_time_stamp(int cpu); void ring_buffer_normalize_time_stamp(int cpu, u64 *ts); +size_t ring_buffer_page_len(void *page); + + /* * The below functions are fine to use outside the tracing facility. */ @@ -138,8 +141,8 @@ static inline int tracing_is_on(void) { return 0; } void *ring_buffer_alloc_read_page(struct ring_buffer *buffer); void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data); -int ring_buffer_read_page(struct ring_buffer *buffer, - void **data_page, int cpu, int full); +int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page, + size_t len, int cpu, int full); enum ring_buffer_flags { RB_FL_OVERWRITE = 1 << 0, diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 9baad7ee4b3..2ad6bae95a3 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -234,6 +234,11 @@ static void rb_init_page(struct buffer_data_page *bpage) local_set(&bpage->commit, 0); } +size_t ring_buffer_page_len(void *page) +{ + return local_read(&((struct buffer_data_page *)page)->commit); +} + /* * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing * this issue out. @@ -2378,8 +2383,8 @@ static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer, */ void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) { - unsigned long addr; struct buffer_data_page *bpage; + unsigned long addr; addr = __get_free_page(GFP_KERNEL); if (!addr) @@ -2387,6 +2392,8 @@ void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) bpage = (void *)addr; + rb_init_page(bpage); + return bpage; } @@ -2406,6 +2413,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) * ring_buffer_read_page - extract a page from the ring buffer * @buffer: buffer to extract from * @data_page: the page to use allocated from ring_buffer_alloc_read_page + * @len: amount to extract * @cpu: the cpu of the buffer to extract * @full: should the extraction only happen when the page is full. * @@ -2418,7 +2426,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) * rpage = ring_buffer_alloc_read_page(buffer); * if (!rpage) * return error; - * ret = ring_buffer_read_page(buffer, &rpage, cpu, 0); + * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); * if (ret >= 0) * process_page(rpage, ret); * @@ -2435,71 +2443,89 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) * <0 if no data has been transferred. */ int ring_buffer_read_page(struct ring_buffer *buffer, - void **data_page, int cpu, int full) + void **data_page, size_t len, int cpu, int full) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; struct ring_buffer_event *event; struct buffer_data_page *bpage; + struct buffer_page *reader; unsigned long flags; + unsigned int commit; unsigned int read; int ret = -1; if (!data_page) - return 0; + return -1; bpage = *data_page; if (!bpage) - return 0; + return -1; spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - /* - * rb_buffer_peek will get the next ring buffer if - * the current reader page is empty. - */ - event = rb_buffer_peek(buffer, cpu, NULL); - if (!event) + reader = rb_get_reader_page(cpu_buffer); + if (!reader) goto out; - /* check for data */ - if (!local_read(&cpu_buffer->reader_page->page->commit)) - goto out; + event = rb_reader_event(cpu_buffer); + + read = reader->read; + commit = rb_page_commit(reader); - read = cpu_buffer->reader_page->read; /* - * If the writer is already off of the read page, then simply - * switch the read page with the given page. Otherwise - * we need to copy the data from the reader to the writer. + * If len > what's left on the page, and the writer is also off of + * the read page, then simply switch the read page with the given + * page. Otherwise we need to copy the data from the reader to the + * writer. */ - if (cpu_buffer->reader_page == cpu_buffer->commit_page) { - unsigned int commit = rb_page_commit(cpu_buffer->reader_page); + if ((len < (commit - read)) || + cpu_buffer->reader_page == cpu_buffer->commit_page) { struct buffer_data_page *rpage = cpu_buffer->reader_page->page; + unsigned int pos = read; + unsigned int size; if (full) goto out; - /* The writer is still on the reader page, we must copy */ - memcpy(bpage->data + read, rpage->data + read, commit - read); - /* consume what was read */ - cpu_buffer->reader_page->read = commit; + if (len > (commit - read)) + len = (commit - read); + + size = rb_event_length(event); + + if (len < size) + goto out; + + /* Need to copy one event at a time */ + do { + memcpy(bpage->data + pos, rpage->data + pos, size); + + len -= size; + + rb_advance_reader(cpu_buffer); + pos = reader->read; + + event = rb_reader_event(cpu_buffer); + size = rb_event_length(event); + } while (len > size); /* update bpage */ - local_set(&bpage->commit, commit); - if (!read) - bpage->time_stamp = rpage->time_stamp; + local_set(&bpage->commit, pos); + bpage->time_stamp = rpage->time_stamp; + } else { /* swap the pages */ rb_init_page(bpage); - bpage = cpu_buffer->reader_page->page; - cpu_buffer->reader_page->page = *data_page; - local_set(&cpu_buffer->reader_page->write, 0); - cpu_buffer->reader_page->read = 0; + bpage = reader->page; + reader->page = *data_page; + local_set(&reader->write, 0); + reader->read = 0; *data_page = bpage; + + /* update the entry counter */ + rb_remove_entries(cpu_buffer, bpage, read); } ret = read; - /* update the entry counter */ - rb_remove_entries(cpu_buffer, bpage, read); out: spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); -- cgit v1.2.3-70-g09d2 From e3d6bf0a0781a269f34250fd41e0d3dbfe540cf1 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 3 Mar 2009 13:53:07 -0500 Subject: ring-buffer: replace sizeof of event header with offsetof Impact: fix to possible alignment problems on some archs. Some arch compilers include an NULL char array in the sizeof field. Since the ring_buffer_event type includes one of these, it is better to use the "offsetof" instead, to avoid strange bugs on these archs. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2ad6bae95a3..27cf834d8b4 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -132,7 +132,7 @@ void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) } EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); -#define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event)) +#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) #define RB_ALIGNMENT 4U #define RB_MAX_SMALL_DATA 28 -- cgit v1.2.3-70-g09d2 From 474d32b68d6d842f3e710e9ae9fe2568c53339f8 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 3 Mar 2009 19:51:40 -0500 Subject: ring-buffer: make ring_buffer_read_page read from start on partial page Impact: dont leave holes in read buffer page The ring_buffer_read_page swaps a given page with the reader page of the ring buffer, if certain conditions are set: 1) requested length is big enough to hold entire page data 2) a writer is not currently on the page 3) the page is not partially consumed. Instead of swapping with the supplied page. It copies the data to the supplied page instead. But currently the data is copied in the same offset as the source page. This causes a hole at the start of the reader page. This complicates the use of this function. Instead, it should copy the data at the beginning of the function and update the index fields accordingly. Other small clean ups are also done in this patch. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 43 +++++++++++++++++++++++++++++++++---------- 1 file changed, 33 insertions(+), 10 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 27cf834d8b4..f2a163db52f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -61,6 +61,8 @@ enum { static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; +#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) + /** * tracing_on - enable all tracing buffers * @@ -234,9 +236,16 @@ static void rb_init_page(struct buffer_data_page *bpage) local_set(&bpage->commit, 0); } +/** + * ring_buffer_page_len - the size of data on the page. + * @page: The page to read + * + * Returns the amount of data on the page, including buffer page header. + */ size_t ring_buffer_page_len(void *page) { - return local_read(&((struct buffer_data_page *)page)->commit); + return local_read(&((struct buffer_data_page *)page)->commit) + + BUF_PAGE_HDR_SIZE; } /* @@ -259,7 +268,7 @@ static inline int test_time_stamp(u64 delta) return 0; } -#define BUF_PAGE_SIZE (PAGE_SIZE - offsetof(struct buffer_data_page, data)) +#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) /* * head_page == tail_page && head == tail then buffer is empty. @@ -2454,6 +2463,15 @@ int ring_buffer_read_page(struct ring_buffer *buffer, unsigned int read; int ret = -1; + /* + * If len is not big enough to hold the page header, then + * we can not copy anything. + */ + if (len <= BUF_PAGE_HDR_SIZE) + return -1; + + len -= BUF_PAGE_HDR_SIZE; + if (!data_page) return -1; @@ -2473,15 +2491,17 @@ int ring_buffer_read_page(struct ring_buffer *buffer, commit = rb_page_commit(reader); /* - * If len > what's left on the page, and the writer is also off of - * the read page, then simply switch the read page with the given - * page. Otherwise we need to copy the data from the reader to the - * writer. + * If this page has been partially read or + * if len is not big enough to read the rest of the page or + * a writer is still on the page, then + * we must copy the data from the page to the buffer. + * Otherwise, we can simply swap the page with the one passed in. */ - if ((len < (commit - read)) || + if (read || (len < (commit - read)) || cpu_buffer->reader_page == cpu_buffer->commit_page) { struct buffer_data_page *rpage = cpu_buffer->reader_page->page; - unsigned int pos = read; + unsigned int rpos = read; + unsigned int pos = 0; unsigned int size; if (full) @@ -2497,12 +2517,13 @@ int ring_buffer_read_page(struct ring_buffer *buffer, /* Need to copy one event at a time */ do { - memcpy(bpage->data + pos, rpage->data + pos, size); + memcpy(bpage->data + pos, rpage->data + rpos, size); len -= size; rb_advance_reader(cpu_buffer); - pos = reader->read; + rpos = reader->read; + pos += size; event = rb_reader_event(cpu_buffer); size = rb_event_length(event); @@ -2512,6 +2533,8 @@ int ring_buffer_read_page(struct ring_buffer *buffer, local_set(&bpage->commit, pos); bpage->time_stamp = rpage->time_stamp; + /* we copied everything to the beginning */ + read = 0; } else { /* swap the pages */ rb_init_page(bpage); -- cgit v1.2.3-70-g09d2 From 4f3640f8a358f2183a8c966f299eeb55ca523e06 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 3 Mar 2009 23:52:42 -0500 Subject: ring-buffer: fix timestamp in partial ring_buffer_page_read If a partial ring_buffer_page_read happens, then some of the incremental timestamps may be lost. This patch writes the recent timestamp into the page that is passed back to the caller. A partial ring_buffer_page_read is where the full page would not be written back to the user, and instead, just part of the page is copied to the user. A full page would be a page swap with the ring buffer and the timestamps would be correct. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f2a163db52f..f7473645b9c 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2461,6 +2461,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, unsigned long flags; unsigned int commit; unsigned int read; + u64 save_timestamp; int ret = -1; /* @@ -2515,6 +2516,9 @@ int ring_buffer_read_page(struct ring_buffer *buffer, if (len < size) goto out; + /* save the current timestamp, since the user will need it */ + save_timestamp = cpu_buffer->read_stamp; + /* Need to copy one event at a time */ do { memcpy(bpage->data + pos, rpage->data + rpos, size); @@ -2531,7 +2535,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, /* update bpage */ local_set(&bpage->commit, pos); - bpage->time_stamp = rpage->time_stamp; + bpage->time_stamp = save_timestamp; /* we copied everything to the beginning */ read = 0; -- cgit v1.2.3-70-g09d2 From 5e2336a0d47c9661a40cc5ef85135ce1406af6e8 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 5 Mar 2009 21:44:55 -0500 Subject: tracing: make all file_operations const Impact: cleanup All file_operations structures should be constant. No one is going to change them. Reported-by: Andrew Morton Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 10 +++++----- kernel/trace/ring_buffer.c | 2 +- kernel/trace/trace.c | 24 ++++++++++++------------ kernel/trace/trace_sysprof.c | 2 +- 4 files changed, 19 insertions(+), 19 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 5a3a06b21ee..d7a06a0d944 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1869,21 +1869,21 @@ ftrace_notrace_release(struct inode *inode, struct file *file) return ftrace_regex_release(inode, file, 0); } -static struct file_operations ftrace_avail_fops = { +static const struct file_operations ftrace_avail_fops = { .open = ftrace_avail_open, .read = seq_read, .llseek = seq_lseek, .release = ftrace_avail_release, }; -static struct file_operations ftrace_failures_fops = { +static const struct file_operations ftrace_failures_fops = { .open = ftrace_failures_open, .read = seq_read, .llseek = seq_lseek, .release = ftrace_avail_release, }; -static struct file_operations ftrace_filter_fops = { +static const struct file_operations ftrace_filter_fops = { .open = ftrace_filter_open, .read = ftrace_regex_read, .write = ftrace_filter_write, @@ -1891,7 +1891,7 @@ static struct file_operations ftrace_filter_fops = { .release = ftrace_filter_release, }; -static struct file_operations ftrace_notrace_fops = { +static const struct file_operations ftrace_notrace_fops = { .open = ftrace_notrace_open, .read = ftrace_regex_read, .write = ftrace_notrace_write, @@ -2423,7 +2423,7 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf, return cnt; } -static struct file_operations ftrace_pid_fops = { +static const struct file_operations ftrace_pid_fops = { .read = ftrace_pid_read, .write = ftrace_pid_write, }; diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f7473645b9c..178858492a8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2606,7 +2606,7 @@ rb_simple_write(struct file *filp, const char __user *ubuf, return cnt; } -static struct file_operations rb_simple_fops = { +static const struct file_operations rb_simple_fops = { .open = tracing_open_generic, .read = rb_simple_read, .write = rb_simple_write, diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c0e9c126339..e6144acf2b7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1882,14 +1882,14 @@ static int show_traces_open(struct inode *inode, struct file *file) return ret; } -static struct file_operations tracing_fops = { +static const struct file_operations tracing_fops = { .open = tracing_open, .read = seq_read, .llseek = seq_lseek, .release = tracing_release, }; -static struct file_operations show_traces_fops = { +static const struct file_operations show_traces_fops = { .open = show_traces_open, .read = seq_read, .release = seq_release, @@ -1982,7 +1982,7 @@ err_unlock: return err; } -static struct file_operations tracing_cpumask_fops = { +static const struct file_operations tracing_cpumask_fops = { .open = tracing_open_generic, .read = tracing_cpumask_read, .write = tracing_cpumask_write, @@ -2134,7 +2134,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, return cnt; } -static struct file_operations tracing_iter_fops = { +static const struct file_operations tracing_iter_fops = { .open = tracing_open_generic, .read = tracing_trace_options_read, .write = tracing_trace_options_write, @@ -2167,7 +2167,7 @@ tracing_readme_read(struct file *filp, char __user *ubuf, readme_msg, strlen(readme_msg)); } -static struct file_operations tracing_readme_fops = { +static const struct file_operations tracing_readme_fops = { .open = tracing_open_generic, .read = tracing_readme_read, }; @@ -2927,25 +2927,25 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, return cnt; } -static struct file_operations tracing_max_lat_fops = { +static const struct file_operations tracing_max_lat_fops = { .open = tracing_open_generic, .read = tracing_max_lat_read, .write = tracing_max_lat_write, }; -static struct file_operations tracing_ctrl_fops = { +static const struct file_operations tracing_ctrl_fops = { .open = tracing_open_generic, .read = tracing_ctrl_read, .write = tracing_ctrl_write, }; -static struct file_operations set_tracer_fops = { +static const struct file_operations set_tracer_fops = { .open = tracing_open_generic, .read = tracing_set_trace_read, .write = tracing_set_trace_write, }; -static struct file_operations tracing_pipe_fops = { +static const struct file_operations tracing_pipe_fops = { .open = tracing_open_pipe, .poll = tracing_poll_pipe, .read = tracing_read_pipe, @@ -2953,13 +2953,13 @@ static struct file_operations tracing_pipe_fops = { .release = tracing_release_pipe, }; -static struct file_operations tracing_entries_fops = { +static const struct file_operations tracing_entries_fops = { .open = tracing_open_generic, .read = tracing_entries_read, .write = tracing_entries_write, }; -static struct file_operations tracing_mark_fops = { +static const struct file_operations tracing_mark_fops = { .open = tracing_open_generic, .write = tracing_mark_write, }; @@ -3240,7 +3240,7 @@ tracing_read_dyn_info(struct file *filp, char __user *ubuf, return r; } -static struct file_operations tracing_dyn_info_fops = { +static const struct file_operations tracing_dyn_info_fops = { .open = tracing_open_generic, .read = tracing_read_dyn_info, }; diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c index c771af4e8f1..91fd19c2149 100644 --- a/kernel/trace/trace_sysprof.c +++ b/kernel/trace/trace_sysprof.c @@ -314,7 +314,7 @@ sysprof_sample_write(struct file *filp, const char __user *ubuf, return cnt; } -static struct file_operations sysprof_sample_fops = { +static const struct file_operations sysprof_sample_fops = { .read = sysprof_sample_read, .write = sysprof_sample_write, }; -- cgit v1.2.3-70-g09d2 From 554f786e284a6ce859d51f62240d615603944c8e Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 11 Mar 2009 22:00:13 -0400 Subject: ring-buffer: only allocate buffers for online cpus Impact: save on memory Currently, a ring buffer was allocated for each "possible_cpus". On some systems, this is the same as NR_CPUS. Thus, if a system defined NR_CPUS = 64 but it only had 1 CPU, we could have possibly 63 useless ring buffers taking up space. With a default buffer of 3 megs, this could be quite drastic. This patch changes the ring buffer code to only allocate ring buffers for online CPUs. If a CPU goes off line, we do not free the buffer. This is because the user may still have trace data in that buffer that they would like to look at. Perhaps in the future we could add code to delete a ring buffer if the CPU is offline and the ring buffer becomes empty. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 266 ++++++++++++++++++++++++++++++++++++--------- kernel/trace/trace.c | 6 - 2 files changed, 216 insertions(+), 56 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 178858492a8..d07c2888396 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include "trace.h" @@ -301,6 +302,10 @@ struct ring_buffer { struct mutex mutex; struct ring_buffer_per_cpu **buffers; + +#ifdef CONFIG_HOTPLUG + struct notifier_block cpu_notify; +#endif }; struct ring_buffer_iter { @@ -459,6 +464,11 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) */ extern int ring_buffer_page_too_big(void); +#ifdef CONFIG_HOTPLUG +static int __cpuinit rb_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu); +#endif + /** * ring_buffer_alloc - allocate a new ring_buffer * @size: the size in bytes per cpu that is needed. @@ -496,7 +506,8 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) if (buffer->pages == 1) buffer->pages++; - cpumask_copy(buffer->cpumask, cpu_possible_mask); + get_online_cpus(); + cpumask_copy(buffer->cpumask, cpu_online_mask); buffer->cpus = nr_cpu_ids; bsize = sizeof(void *) * nr_cpu_ids; @@ -512,6 +523,13 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) goto fail_free_buffers; } +#ifdef CONFIG_HOTPLUG + buffer->cpu_notify.notifier_call = rb_cpu_notify; + buffer->cpu_notify.priority = 0; + register_cpu_notifier(&buffer->cpu_notify); +#endif + + put_online_cpus(); mutex_init(&buffer->mutex); return buffer; @@ -525,6 +543,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) fail_free_cpumask: free_cpumask_var(buffer->cpumask); + put_online_cpus(); fail_free_buffer: kfree(buffer); @@ -541,9 +560,17 @@ ring_buffer_free(struct ring_buffer *buffer) { int cpu; + get_online_cpus(); + +#ifdef CONFIG_HOTPLUG + unregister_cpu_notifier(&buffer->cpu_notify); +#endif + for_each_buffer_cpu(buffer, cpu) rb_free_cpu_buffer(buffer->buffers[cpu]); + put_online_cpus(); + free_cpumask_var(buffer->cpumask); kfree(buffer); @@ -649,16 +676,15 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) return size; mutex_lock(&buffer->mutex); + get_online_cpus(); nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); if (size < buffer_size) { /* easy case, just free pages */ - if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) { - mutex_unlock(&buffer->mutex); - return -1; - } + if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) + goto out_fail; rm_pages = buffer->pages - nr_pages; @@ -677,10 +703,8 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) * add these pages to the cpu_buffers. Otherwise we just free * them all and return -ENOMEM; */ - if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) { - mutex_unlock(&buffer->mutex); - return -1; - } + if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) + goto out_fail; new_pages = nr_pages - buffer->pages; @@ -705,13 +729,12 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) rb_insert_pages(cpu_buffer, &pages, new_pages); } - if (RB_WARN_ON(buffer, !list_empty(&pages))) { - mutex_unlock(&buffer->mutex); - return -1; - } + if (RB_WARN_ON(buffer, !list_empty(&pages))) + goto out_fail; out: buffer->pages = nr_pages; + put_online_cpus(); mutex_unlock(&buffer->mutex); return size; @@ -721,8 +744,18 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) list_del_init(&bpage->list); free_buffer_page(bpage); } + put_online_cpus(); mutex_unlock(&buffer->mutex); return -ENOMEM; + + /* + * Something went totally wrong, and we are too paranoid + * to even clean up the mess. + */ + out_fail: + put_online_cpus(); + mutex_unlock(&buffer->mutex); + return -1; } EXPORT_SYMBOL_GPL(ring_buffer_resize); @@ -1528,11 +1561,15 @@ void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + get_online_cpus(); + if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return; + goto out; cpu_buffer = buffer->buffers[cpu]; atomic_inc(&cpu_buffer->record_disabled); + out: + put_online_cpus(); } EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); @@ -1548,11 +1585,15 @@ void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + get_online_cpus(); + if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return; + goto out; cpu_buffer = buffer->buffers[cpu]; atomic_dec(&cpu_buffer->record_disabled); + out: + put_online_cpus(); } EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); @@ -1564,12 +1605,19 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + unsigned long ret = 0; + + get_online_cpus(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return 0; + goto out; cpu_buffer = buffer->buffers[cpu]; - return cpu_buffer->entries; + ret = cpu_buffer->entries; + out: + put_online_cpus(); + + return ret; } EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); @@ -1581,12 +1629,19 @@ EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + unsigned long ret = 0; + + get_online_cpus(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return 0; + goto out; cpu_buffer = buffer->buffers[cpu]; - return cpu_buffer->overrun; + ret = cpu_buffer->overrun; + out: + put_online_cpus(); + + return ret; } EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); @@ -1603,12 +1658,16 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer) unsigned long entries = 0; int cpu; + get_online_cpus(); + /* if you care about this being correct, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; entries += cpu_buffer->entries; } + put_online_cpus(); + return entries; } EXPORT_SYMBOL_GPL(ring_buffer_entries); @@ -1626,12 +1685,16 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer) unsigned long overruns = 0; int cpu; + get_online_cpus(); + /* if you care about this being correct, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; overruns += cpu_buffer->overrun; } + put_online_cpus(); + return overruns; } EXPORT_SYMBOL_GPL(ring_buffer_overruns); @@ -1663,9 +1726,14 @@ static void rb_iter_reset(struct ring_buffer_iter *iter) */ void ring_buffer_iter_reset(struct ring_buffer_iter *iter) { - struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; + struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; + if (!iter) + return; + + cpu_buffer = iter->cpu_buffer; + spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_iter_reset(iter); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); @@ -1900,9 +1968,6 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) struct buffer_page *reader; int nr_loops = 0; - if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return NULL; - cpu_buffer = buffer->buffers[cpu]; again: @@ -2028,13 +2093,21 @@ struct ring_buffer_event * ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; - struct ring_buffer_event *event; + struct ring_buffer_event *event = NULL; unsigned long flags; + get_online_cpus(); + + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + goto out; + spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_buffer_peek(buffer, cpu, ts); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + out: + put_online_cpus(); + return event; } @@ -2071,24 +2144,31 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_event * ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) { - struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; - struct ring_buffer_event *event; + struct ring_buffer_per_cpu *cpu_buffer; + struct ring_buffer_event *event = NULL; unsigned long flags; + /* might be called in atomic */ + preempt_disable(); + if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return NULL; + goto out; + cpu_buffer = buffer->buffers[cpu]; spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_buffer_peek(buffer, cpu, ts); if (!event) - goto out; + goto out_unlock; rb_advance_reader(cpu_buffer); - out: + out_unlock: spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + out: + preempt_enable(); + return event; } EXPORT_SYMBOL_GPL(ring_buffer_consume); @@ -2109,15 +2189,17 @@ struct ring_buffer_iter * ring_buffer_read_start(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - struct ring_buffer_iter *iter; + struct ring_buffer_iter *iter = NULL; unsigned long flags; + get_online_cpus(); + if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return NULL; + goto out; iter = kmalloc(sizeof(*iter), GFP_KERNEL); if (!iter) - return NULL; + goto out; cpu_buffer = buffer->buffers[cpu]; @@ -2132,6 +2214,9 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu) __raw_spin_unlock(&cpu_buffer->lock); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + out: + put_online_cpus(); + return iter; } EXPORT_SYMBOL_GPL(ring_buffer_read_start); @@ -2224,9 +2309,13 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; unsigned long flags; + int resched; + + /* Can't use get_online_cpus because this can be in atomic */ + resched = ftrace_preempt_disable(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return; + goto out; spin_lock_irqsave(&cpu_buffer->reader_lock, flags); @@ -2237,6 +2326,8 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) __raw_spin_unlock(&cpu_buffer->lock); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + out: + ftrace_preempt_enable(resched); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); @@ -2246,10 +2337,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); */ void ring_buffer_reset(struct ring_buffer *buffer) { + int resched; int cpu; + /* Can't use get_online_cpus because this can be in atomic */ + resched = ftrace_preempt_disable(); + for_each_buffer_cpu(buffer, cpu) ring_buffer_reset_cpu(buffer, cpu); + + ftrace_preempt_enable(resched); } EXPORT_SYMBOL_GPL(ring_buffer_reset); @@ -2262,12 +2359,17 @@ int ring_buffer_empty(struct ring_buffer *buffer) struct ring_buffer_per_cpu *cpu_buffer; int cpu; + get_online_cpus(); + /* yes this is racy, but if you don't like the race, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; if (!rb_per_cpu_empty(cpu_buffer)) return 0; } + + put_online_cpus(); + return 1; } EXPORT_SYMBOL_GPL(ring_buffer_empty); @@ -2280,12 +2382,20 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty); int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + int ret = 1; + + get_online_cpus(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return 1; + goto out; cpu_buffer = buffer->buffers[cpu]; - return rb_per_cpu_empty(cpu_buffer); + ret = rb_per_cpu_empty(cpu_buffer); + + out: + put_online_cpus(); + + return ret; } EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); @@ -2304,32 +2414,37 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, { struct ring_buffer_per_cpu *cpu_buffer_a; struct ring_buffer_per_cpu *cpu_buffer_b; + int ret = -EINVAL; + + get_online_cpus(); if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || !cpumask_test_cpu(cpu, buffer_b->cpumask)) - return -EINVAL; + goto out; /* At least make sure the two buffers are somewhat the same */ if (buffer_a->pages != buffer_b->pages) - return -EINVAL; + goto out; + + ret = -EAGAIN; if (ring_buffer_flags != RB_BUFFERS_ON) - return -EAGAIN; + goto out; if (atomic_read(&buffer_a->record_disabled)) - return -EAGAIN; + goto out; if (atomic_read(&buffer_b->record_disabled)) - return -EAGAIN; + goto out; cpu_buffer_a = buffer_a->buffers[cpu]; cpu_buffer_b = buffer_b->buffers[cpu]; if (atomic_read(&cpu_buffer_a->record_disabled)) - return -EAGAIN; + goto out; if (atomic_read(&cpu_buffer_b->record_disabled)) - return -EAGAIN; + goto out; /* * We can't do a synchronize_sched here because this @@ -2349,7 +2464,11 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, atomic_dec(&cpu_buffer_a->record_disabled); atomic_dec(&cpu_buffer_b->record_disabled); - return 0; + ret = 0; +out: + put_online_cpus(); + + return ret; } EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); @@ -2464,27 +2583,32 @@ int ring_buffer_read_page(struct ring_buffer *buffer, u64 save_timestamp; int ret = -1; + get_online_cpus(); + + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + goto out; + /* * If len is not big enough to hold the page header, then * we can not copy anything. */ if (len <= BUF_PAGE_HDR_SIZE) - return -1; + goto out; len -= BUF_PAGE_HDR_SIZE; if (!data_page) - return -1; + goto out; bpage = *data_page; if (!bpage) - return -1; + goto out; spin_lock_irqsave(&cpu_buffer->reader_lock, flags); reader = rb_get_reader_page(cpu_buffer); if (!reader) - goto out; + goto out_unlock; event = rb_reader_event(cpu_buffer); @@ -2506,7 +2630,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, unsigned int size; if (full) - goto out; + goto out_unlock; if (len > (commit - read)) len = (commit - read); @@ -2514,7 +2638,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, size = rb_event_length(event); if (len < size) - goto out; + goto out_unlock; /* save the current timestamp, since the user will need it */ save_timestamp = cpu_buffer->read_stamp; @@ -2553,9 +2677,12 @@ int ring_buffer_read_page(struct ring_buffer *buffer, } ret = read; - out: + out_unlock: spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + out: + put_online_cpus(); + return ret; } @@ -2629,3 +2756,42 @@ static __init int rb_init_debugfs(void) } fs_initcall(rb_init_debugfs); + +#ifdef CONFIG_HOTPLUG +static int __cpuinit rb_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + struct ring_buffer *buffer = + container_of(self, struct ring_buffer, cpu_notify); + long cpu = (long)hcpu; + + switch (action) { + case CPU_UP_PREPARE: + case CPU_UP_PREPARE_FROZEN: + if (cpu_isset(cpu, *buffer->cpumask)) + return NOTIFY_OK; + + buffer->buffers[cpu] = + rb_allocate_cpu_buffer(buffer, cpu); + if (!buffer->buffers[cpu]) { + WARN(1, "failed to allocate ring buffer on CPU %ld\n", + cpu); + return NOTIFY_OK; + } + smp_wmb(); + cpu_set(cpu, *buffer->cpumask); + break; + case CPU_DOWN_PREPARE: + case CPU_DOWN_PREPARE_FROZEN: + /* + * Do nothing. + * If we were to free the buffer, then the user would + * lose any trace that was in the buffer. + */ + break; + default: + break; + } + return NOTIFY_OK; +} +#endif diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e60f4be10d6..14c98f6a47b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1805,17 +1805,11 @@ __tracing_open(struct inode *inode, struct file *file) iter->buffer_iter[cpu] = ring_buffer_read_start(iter->tr->buffer, cpu); - - if (!iter->buffer_iter[cpu]) - goto fail_buffer; } } else { cpu = iter->cpu_file; iter->buffer_iter[cpu] = ring_buffer_read_start(iter->tr->buffer, cpu); - - if (!iter->buffer_iter[cpu]) - goto fail; } /* TODO stop tracer */ -- cgit v1.2.3-70-g09d2 From 59222efe2d184956464abe5b637bc842ff053b93 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 12 Mar 2009 11:46:03 -0400 Subject: ring-buffer: use CONFIG_HOTPLUG_CPU not CONFIG_HOTPLUG The hotplug code in the ring buffers is for use with CPU hotplug, not generic hotplug. Reported-by: Andrew Morton Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index d07c2888396..035b56c3a6c 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -303,7 +303,7 @@ struct ring_buffer { struct ring_buffer_per_cpu **buffers; -#ifdef CONFIG_HOTPLUG +#ifdef CONFIG_HOTPLUG_CPU struct notifier_block cpu_notify; #endif }; @@ -464,7 +464,7 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) */ extern int ring_buffer_page_too_big(void); -#ifdef CONFIG_HOTPLUG +#ifdef CONFIG_HOTPLUG_CPU static int __cpuinit rb_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu); #endif @@ -523,7 +523,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) goto fail_free_buffers; } -#ifdef CONFIG_HOTPLUG +#ifdef CONFIG_HOTPLUG_CPU buffer->cpu_notify.notifier_call = rb_cpu_notify; buffer->cpu_notify.priority = 0; register_cpu_notifier(&buffer->cpu_notify); @@ -562,7 +562,7 @@ ring_buffer_free(struct ring_buffer *buffer) get_online_cpus(); -#ifdef CONFIG_HOTPLUG +#ifdef CONFIG_HOTPLUG_CPU unregister_cpu_notifier(&buffer->cpu_notify); #endif @@ -2757,7 +2757,7 @@ static __init int rb_init_debugfs(void) fs_initcall(rb_init_debugfs); -#ifdef CONFIG_HOTPLUG +#ifdef CONFIG_HOTPLUG_CPU static int __cpuinit rb_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { -- cgit v1.2.3-70-g09d2 From 8aabee573dff131a085c63de7667eacd94ba4ccb Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 12 Mar 2009 13:13:49 -0400 Subject: ring-buffer: remove unneeded get_online_cpus Impact: speed up and remove possible races The get_online_cpus was added to the ring buffer because the original design would free the ring buffer on a CPU that was being taken off line. The final design kept the ring buffer around even when the CPU was taken off line. This is to allow a user to still read the information on that ring buffer. Most of the get_online_cpus are no longer needed since the ring buffer will not disappear from the use cases. Reported-by: KOSAKI Motohiro Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 90 ++++++++-------------------------------------- 1 file changed, 14 insertions(+), 76 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 035b56c3a6c..2c36be9fac2 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1561,15 +1561,11 @@ void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - get_online_cpus(); - if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return; cpu_buffer = buffer->buffers[cpu]; atomic_inc(&cpu_buffer->record_disabled); - out: - put_online_cpus(); } EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); @@ -1585,15 +1581,11 @@ void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - get_online_cpus(); - if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return; cpu_buffer = buffer->buffers[cpu]; atomic_dec(&cpu_buffer->record_disabled); - out: - put_online_cpus(); } EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); @@ -1605,17 +1597,13 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - unsigned long ret = 0; - - get_online_cpus(); + unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return 0; cpu_buffer = buffer->buffers[cpu]; ret = cpu_buffer->entries; - out: - put_online_cpus(); return ret; } @@ -1629,17 +1617,13 @@ EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - unsigned long ret = 0; - - get_online_cpus(); + unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return 0; cpu_buffer = buffer->buffers[cpu]; ret = cpu_buffer->overrun; - out: - put_online_cpus(); return ret; } @@ -1658,16 +1642,12 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer) unsigned long entries = 0; int cpu; - get_online_cpus(); - /* if you care about this being correct, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; entries += cpu_buffer->entries; } - put_online_cpus(); - return entries; } EXPORT_SYMBOL_GPL(ring_buffer_entries); @@ -1685,16 +1665,12 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer) unsigned long overruns = 0; int cpu; - get_online_cpus(); - /* if you care about this being correct, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; overruns += cpu_buffer->overrun; } - put_online_cpus(); - return overruns; } EXPORT_SYMBOL_GPL(ring_buffer_overruns); @@ -2093,21 +2069,16 @@ struct ring_buffer_event * ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; - struct ring_buffer_event *event = NULL; + struct ring_buffer_event *event; unsigned long flags; - get_online_cpus(); - if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return NULL; spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_buffer_peek(buffer, cpu, ts); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); - out: - put_online_cpus(); - return event; } @@ -2189,17 +2160,15 @@ struct ring_buffer_iter * ring_buffer_read_start(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - struct ring_buffer_iter *iter = NULL; + struct ring_buffer_iter *iter; unsigned long flags; - get_online_cpus(); - if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return NULL; iter = kmalloc(sizeof(*iter), GFP_KERNEL); if (!iter) - goto out; + return NULL; cpu_buffer = buffer->buffers[cpu]; @@ -2214,9 +2183,6 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu) __raw_spin_unlock(&cpu_buffer->lock); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); - out: - put_online_cpus(); - return iter; } EXPORT_SYMBOL_GPL(ring_buffer_read_start); @@ -2309,13 +2275,9 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; unsigned long flags; - int resched; - - /* Can't use get_online_cpus because this can be in atomic */ - resched = ftrace_preempt_disable(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return; spin_lock_irqsave(&cpu_buffer->reader_lock, flags); @@ -2326,8 +2288,6 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) __raw_spin_unlock(&cpu_buffer->lock); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); - out: - ftrace_preempt_enable(resched); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); @@ -2337,16 +2297,10 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); */ void ring_buffer_reset(struct ring_buffer *buffer) { - int resched; int cpu; - /* Can't use get_online_cpus because this can be in atomic */ - resched = ftrace_preempt_disable(); - for_each_buffer_cpu(buffer, cpu) ring_buffer_reset_cpu(buffer, cpu); - - ftrace_preempt_enable(resched); } EXPORT_SYMBOL_GPL(ring_buffer_reset); @@ -2359,8 +2313,6 @@ int ring_buffer_empty(struct ring_buffer *buffer) struct ring_buffer_per_cpu *cpu_buffer; int cpu; - get_online_cpus(); - /* yes this is racy, but if you don't like the race, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; @@ -2368,8 +2320,6 @@ int ring_buffer_empty(struct ring_buffer *buffer) return 0; } - put_online_cpus(); - return 1; } EXPORT_SYMBOL_GPL(ring_buffer_empty); @@ -2382,18 +2332,14 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty); int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - int ret = 1; - - get_online_cpus(); + int ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return 1; cpu_buffer = buffer->buffers[cpu]; ret = rb_per_cpu_empty(cpu_buffer); - out: - put_online_cpus(); return ret; } @@ -2416,8 +2362,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, struct ring_buffer_per_cpu *cpu_buffer_b; int ret = -EINVAL; - get_online_cpus(); - if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || !cpumask_test_cpu(cpu, buffer_b->cpumask)) goto out; @@ -2466,8 +2410,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, ret = 0; out: - put_online_cpus(); - return ret; } EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); @@ -2583,8 +2525,6 @@ int ring_buffer_read_page(struct ring_buffer *buffer, u64 save_timestamp; int ret = -1; - get_online_cpus(); - if (!cpumask_test_cpu(cpu, buffer->cpumask)) goto out; @@ -2681,8 +2621,6 @@ int ring_buffer_read_page(struct ring_buffer *buffer, spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); out: - put_online_cpus(); - return ret; } -- cgit v1.2.3-70-g09d2 From 5cc985488845ec7227a2c5cfd2fd62cf57fb411a Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 12 Mar 2009 22:24:17 -0400 Subject: ring-buffer: document reader page design In a private email conversation I explained how the ring buffer page worked by using silly ASCII art. Ingo suggested that I add that to the comments of the code. Here it is. Requested-by: Ingo Molnar Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2c36be9fac2..58128ad2fde 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -21,6 +21,74 @@ #include "trace.h" +/* + * The ring buffer is made up of a list of pages. A separate list of pages is + * allocated for each CPU. A writer may only write to a buffer that is + * associated with the CPU it is currently executing on. A reader may read + * from any per cpu buffer. + * + * The reader is special. For each per cpu buffer, the reader has its own + * reader page. When a reader has read the entire reader page, this reader + * page is swapped with another page in the ring buffer. + * + * Now, as long as the writer is off the reader page, the reader can do what + * ever it wants with that page. The writer will never write to that page + * again (as long as it is out of the ring buffer). + * + * Here's some silly ASCII art. + * + * +------+ + * |reader| RING BUFFER + * |page | + * +------+ +---+ +---+ +---+ + * | |-->| |-->| | + * +---+ +---+ +---+ + * ^ | + * | | + * +---------------+ + * + * + * +------+ + * |reader| RING BUFFER + * |page |------------------v + * +------+ +---+ +---+ +---+ + * | |-->| |-->| | + * +---+ +---+ +---+ + * ^ | + * | | + * +---------------+ + * + * + * +------+ + * |reader| RING BUFFER + * |page |------------------v + * +------+ +---+ +---+ +---+ + * ^ | |-->| |-->| | + * | +---+ +---+ +---+ + * | | + * | | + * +------------------------------+ + * + * + * +------+ + * |buffer| RING BUFFER + * |page |------------------v + * +------+ +---+ +---+ +---+ + * ^ | | | |-->| | + * | New +---+ +---+ +---+ + * | Reader------^ | + * | page | + * +------------------------------+ + * + * + * After we make this swap, the reader can hand this page off to the splice + * code and be done with it. It can even allocate a new page if it needs to + * and swap that into the ring buffer. + * + * We will be using cmpxchg soon to make all this lockless. + * + */ + /* * A fast way to enable or disable all ring buffers is to * call tracing_on or tracing_off. Turning off the ring buffers -- cgit v1.2.3-70-g09d2 From 37886f6a9f62d22530ffee8d3f9215c8345b6969 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 17 Mar 2009 17:22:06 -0400 Subject: ring-buffer: add api to allow a tracer to change clock source This patch adds a new function called ring_buffer_set_clock that allows a tracer to assign its own clock source to the buffer. Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 7 +++-- kernel/trace/ring_buffer.c | 65 ++++++++++++++++++++++++++------------------- kernel/trace/trace.c | 21 ++++++++++----- 3 files changed, 57 insertions(+), 36 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index b1a0068a555..9e6052bd1a1 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -118,8 +118,11 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer); unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu); unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu); -u64 ring_buffer_time_stamp(int cpu); -void ring_buffer_normalize_time_stamp(int cpu, u64 *ts); +u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu); +void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, + int cpu, u64 *ts); +void ring_buffer_set_clock(struct ring_buffer *buffer, + u64 (*clock)(void)); size_t ring_buffer_page_len(void *page); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 58128ad2fde..bbf51922a8c 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -180,29 +180,6 @@ EXPORT_SYMBOL_GPL(tracing_is_on); #include "trace.h" -/* Up this if you want to test the TIME_EXTENTS and normalization */ -#define DEBUG_SHIFT 0 - -u64 ring_buffer_time_stamp(int cpu) -{ - u64 time; - - preempt_disable_notrace(); - /* shift to debug/test normalization and TIME_EXTENTS */ - time = trace_clock_local() << DEBUG_SHIFT; - preempt_enable_no_resched_notrace(); - - return time; -} -EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); - -void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) -{ - /* Just stupid testing the normalize function and deltas */ - *ts >>= DEBUG_SHIFT; -} -EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); - #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) #define RB_ALIGNMENT 4U #define RB_MAX_SMALL_DATA 28 @@ -374,6 +351,7 @@ struct ring_buffer { #ifdef CONFIG_HOTPLUG_CPU struct notifier_block cpu_notify; #endif + u64 (*clock)(void); }; struct ring_buffer_iter { @@ -394,6 +372,30 @@ struct ring_buffer_iter { _____ret; \ }) +/* Up this if you want to test the TIME_EXTENTS and normalization */ +#define DEBUG_SHIFT 0 + +u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) +{ + u64 time; + + preempt_disable_notrace(); + /* shift to debug/test normalization and TIME_EXTENTS */ + time = buffer->clock() << DEBUG_SHIFT; + preempt_enable_no_resched_notrace(); + + return time; +} +EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); + +void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, + int cpu, u64 *ts) +{ + /* Just stupid testing the normalize function and deltas */ + *ts >>= DEBUG_SHIFT; +} +EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); + /** * check_pages - integrity check of buffer pages * @cpu_buffer: CPU buffer with pages to test @@ -569,6 +571,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); buffer->flags = flags; + buffer->clock = trace_clock_local; /* need at least two pages */ if (buffer->pages == 1) @@ -645,6 +648,12 @@ ring_buffer_free(struct ring_buffer *buffer) } EXPORT_SYMBOL_GPL(ring_buffer_free); +void ring_buffer_set_clock(struct ring_buffer *buffer, + u64 (*clock)(void)) +{ + buffer->clock = clock; +} + static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); static void @@ -1191,7 +1200,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, cpu_buffer->tail_page = next_page; /* reread the time stamp */ - *ts = ring_buffer_time_stamp(cpu_buffer->cpu); + *ts = ring_buffer_time_stamp(buffer, cpu_buffer->cpu); cpu_buffer->tail_page->page->time_stamp = *ts; } @@ -1334,7 +1343,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) return NULL; - ts = ring_buffer_time_stamp(cpu_buffer->cpu); + ts = ring_buffer_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu); /* * Only the first commit can update the timestamp. @@ -2051,7 +2060,8 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) case RINGBUF_TYPE_DATA: if (ts) { *ts = cpu_buffer->read_stamp + event->time_delta; - ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); + ring_buffer_normalize_time_stamp(buffer, + cpu_buffer->cpu, ts); } return event; @@ -2112,7 +2122,8 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) case RINGBUF_TYPE_DATA: if (ts) { *ts = iter->read_stamp + event->time_delta; - ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); + ring_buffer_normalize_time_stamp(buffer, + cpu_buffer->cpu, ts); } return event; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8f89690230e..3be2f788e10 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -155,13 +155,6 @@ ns2usecs(cycle_t nsec) return nsec; } -cycle_t ftrace_now(int cpu) -{ - u64 ts = ring_buffer_time_stamp(cpu); - ring_buffer_normalize_time_stamp(cpu, &ts); - return ts; -} - /* * The global_trace is the descriptor that holds the tracing * buffers for the live tracing. For each CPU, it contains @@ -178,6 +171,20 @@ static struct trace_array global_trace; static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu); +cycle_t ftrace_now(int cpu) +{ + u64 ts; + + /* Early boot up does not have a buffer yet */ + if (!global_trace.buffer) + return trace_clock_local(); + + ts = ring_buffer_time_stamp(global_trace.buffer, cpu); + ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts); + + return ts; +} + /* * The max_tr is used to snapshot the global_trace when a maximum * latency is reached. Some tracers will use this to store a maximum -- cgit v1.2.3-70-g09d2 From 3bf832ce1fe6988148d392599f34ca0c6a34427d Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 19 Mar 2009 14:47:33 +0100 Subject: tracing/ring-buffer: fix non cpu hotplug case Impact: fix warning with irqsoff tracer The ring buffer allocates its buffers on pre-smp time (early_initcall). It means that, at first, only the boot cpu buffer is allocated and the ring-buffer cpumask only has the boot cpu set (cpu_online_mask). Later, the secondary cpu will show up and the ring-buffer will be notified about this event: the appropriate buffer will be allocated and the cpumask will be updated. Unfortunately, if !CONFIG_CPU_HOTPLUG, the ring-buffer will not be notified about the secondary cpus, meaning that the cpumask will have only the cpu boot set, and only one cpu buffer allocated. We fix that by using cpu_possible_mask if !CONFIG_CPU_HOTPLUG. This patch fixes the following warning with irqsoff tracer running: [ 169.317794] WARNING: at kernel/trace/trace.c:466 update_max_tr_single+0xcc/0xf3() [ 169.318002] Hardware name: AMILO Li 2727 [ 169.318002] Modules linked in: [ 169.318002] Pid: 5624, comm: bash Not tainted 2.6.29-rc8-tip-02636-g6aafa6c #11 [ 169.318002] Call Trace: [ 169.318002] [] warn_slowpath+0xea/0x13d [ 169.318002] [] ? ftrace_call+0x5/0x2b [ 169.318002] [] ? ftrace_call+0x5/0x2b [ 169.318002] [] ? ftrace_call+0x0/0x2b [ 169.318002] [] ? ftrace_modify_code+0xa9/0x108 [ 169.318002] [] ? trace_hardirqs_off+0x25/0x27 [ 169.318002] [] ? _spin_unlock_irqrestore+0x1f/0x2d [ 169.318002] [] ? ring_buffer_reset_cpu+0xf6/0xfb [ 169.318002] [] ? ring_buffer_reset+0x36/0x48 [ 169.318002] [] update_max_tr_single+0xcc/0xf3 [ 169.318002] [] ? sysret_check+0x22/0x5d [ 169.318002] [] stop_critical_timing+0x142/0x204 [ 169.318002] [] trace_hardirqs_on_caller+0x23/0x25 [ 169.318002] [] trace_hardirqs_on_thunk+0x3a/0x3c [ 169.318002] [] ? sysret_check+0x22/0x5d [ 169.318002] ---[ end trace db76cbf775a750cf ]--- Because this tracer may try to swap two cpu ring buffers for an unregistered cpu on the ring buffer. This patch might also fix a fair loss of traces due to unallocated buffers for secondary cpus. Reported-by: Ingo Molnar Signed-off-by: Frederic Weisbecker Acked-b: Steven Rostedt LKML-Reference: <1237470453-5427-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index bbf51922a8c..384ca5d9d72 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -577,8 +577,17 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) if (buffer->pages == 1) buffer->pages++; + /* + * In case of non-hotplug cpu, if the ring-buffer is allocated + * in early initcall, it will not be notified of secondary cpus. + * In that off case, we need to allocate for all possible cpus. + */ +#ifdef CONFIG_HOTPLUG_CPU get_online_cpus(); cpumask_copy(buffer->cpumask, cpu_online_mask); +#else + cpumask_copy(buffer->cpumask, cpu_possible_mask); +#endif buffer->cpus = nr_cpu_ids; bsize = sizeof(void *) * nr_cpu_ids; -- cgit v1.2.3-70-g09d2 From 09c9e84d474d917d9de5b9011ed2064b03a19677 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sat, 21 Mar 2009 04:33:36 +0100 Subject: tracing/ring-buffer: don't annotate rb_cpu_notify with __cpuinit Impact: remove a section warning CONFIG_DEBUG_SECTION_MISMATCH raises the following warning on -tip: WARNING: kernel/trace/built-in.o(.text+0x5bc5): Section mismatch in reference from the function ring_buffer_alloc() to the function .cpuinit.text:rb_cpu_notify() The function ring_buffer_alloc() references the function __cpuinit rb_cpu_notify(). This is actually harmless. The code in the ring buffer don't build rb_cpu_notify and other cpu hotplug stuffs when !CONFIG_HOTPLUG_CPU so we have no risk to reference freed memory here (it would even be harmless if we unconditionally build it because register_cpu_notifier would do nothing when !CONFIG_HOTPLUG_CPU. But since ring_buffer_alloc() can be called everytime, we don't want it to be annotated with __cpuinit so we drop the __cpuinit from rb_cpu_notify. This is not a waste of memory because it is only defined and used on CONFIG_HOTPLUG_CPU. Signed-off-by: Frederic Weisbecker Cc: Steven Rostedt LKML-Reference: <1237606416-22268-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 384ca5d9d72..808b14bbf07 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -535,8 +535,8 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) extern int ring_buffer_page_too_big(void); #ifdef CONFIG_HOTPLUG_CPU -static int __cpuinit rb_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu); +static int rb_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu); #endif /** @@ -2784,8 +2784,8 @@ static __init int rb_init_debugfs(void) fs_initcall(rb_init_debugfs); #ifdef CONFIG_HOTPLUG_CPU -static int __cpuinit rb_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu) +static int rb_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) { struct ring_buffer *buffer = container_of(self, struct ring_buffer, cpu_notify); -- cgit v1.2.3-70-g09d2 From 2d622719f1572ef31e0616444a515eba3094d050 Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Sun, 22 Mar 2009 03:30:49 -0500 Subject: tracing: add ring_buffer_event_discard() to ring buffer This patch overloads RINGBUF_TYPE_PADDING to provide a way to discard events from the ring buffer, for the event-filtering mechanism introduced in a subsequent patch. I did the initial version but thanks to Steven Rostedt for adding the parts that actually made it work. ;-) Signed-off-by: Tom Zanussi Acked-by: Frederic Weisbecker Signed-off-by: Ingo Molnar --- include/linux/ring_buffer.h | 11 +++-- kernel/trace/ring_buffer.c | 117 ++++++++++++++++++++++++++++++++++++-------- 2 files changed, 105 insertions(+), 23 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 9e6052bd1a1..e1b7b217388 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -18,10 +18,13 @@ struct ring_buffer_event { /** * enum ring_buffer_type - internal ring buffer types * - * @RINGBUF_TYPE_PADDING: Left over page padding - * array is ignored - * size is variable depending on how much + * @RINGBUF_TYPE_PADDING: Left over page padding or discarded event + * If time_delta is 0: + * array is ignored + * size is variable depending on how much * padding is needed + * If time_delta is non zero: + * everything else same as RINGBUF_TYPE_DATA * * @RINGBUF_TYPE_TIME_EXTEND: Extend the time delta * array[0] = time delta (28 .. 59) @@ -65,6 +68,8 @@ ring_buffer_event_time_delta(struct ring_buffer_event *event) return event->time_delta; } +void ring_buffer_event_discard(struct ring_buffer_event *event); + /* * size is in bytes for each per CPU buffer. */ diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 384ca5d9d72..a09027ec171 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -189,16 +189,65 @@ enum { RB_LEN_TIME_STAMP = 16, }; -/* inline for ring buffer fast paths */ +static inline int rb_null_event(struct ring_buffer_event *event) +{ + return event->type == RINGBUF_TYPE_PADDING && event->time_delta == 0; +} + +static inline int rb_discarded_event(struct ring_buffer_event *event) +{ + return event->type == RINGBUF_TYPE_PADDING && event->time_delta; +} + +static void rb_event_set_padding(struct ring_buffer_event *event) +{ + event->type = RINGBUF_TYPE_PADDING; + event->time_delta = 0; +} + +/** + * ring_buffer_event_discard - discard an event in the ring buffer + * @buffer: the ring buffer + * @event: the event to discard + * + * Sometimes a event that is in the ring buffer needs to be ignored. + * This function lets the user discard an event in the ring buffer + * and then that event will not be read later. + * + * Note, it is up to the user to be careful with this, and protect + * against races. If the user discards an event that has been consumed + * it is possible that it could corrupt the ring buffer. + */ +void ring_buffer_event_discard(struct ring_buffer_event *event) +{ + event->type = RINGBUF_TYPE_PADDING; + /* time delta must be non zero */ + if (!event->time_delta) + event->time_delta = 1; +} + static unsigned -rb_event_length(struct ring_buffer_event *event) +rb_event_data_length(struct ring_buffer_event *event) { unsigned length; + if (event->len) + length = event->len * RB_ALIGNMENT; + else + length = event->array[0]; + return length + RB_EVNT_HDR_SIZE; +} + +/* inline for ring buffer fast paths */ +static unsigned +rb_event_length(struct ring_buffer_event *event) +{ switch (event->type) { case RINGBUF_TYPE_PADDING: - /* undefined */ - return -1; + if (rb_null_event(event)) + /* undefined */ + return -1; + return rb_event_data_length(event); case RINGBUF_TYPE_TIME_EXTEND: return RB_LEN_TIME_EXTEND; @@ -207,11 +256,7 @@ rb_event_length(struct ring_buffer_event *event) return RB_LEN_TIME_STAMP; case RINGBUF_TYPE_DATA: - if (event->len) - length = event->len * RB_ALIGNMENT; - else - length = event->array[0]; - return length + RB_EVNT_HDR_SIZE; + return rb_event_data_length(event); default: BUG(); } @@ -845,11 +890,6 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) } EXPORT_SYMBOL_GPL(ring_buffer_resize); -static inline int rb_null_event(struct ring_buffer_event *event) -{ - return event->type == RINGBUF_TYPE_PADDING; -} - static inline void * __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) { @@ -1219,7 +1259,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, if (tail < BUF_PAGE_SIZE) { /* Mark the rest of the page with padding */ event = __rb_page_index(tail_page, tail); - event->type = RINGBUF_TYPE_PADDING; + rb_event_set_padding(event); } if (tail <= BUF_PAGE_SIZE) @@ -1969,7 +2009,7 @@ static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) event = rb_reader_event(cpu_buffer); - if (event->type == RINGBUF_TYPE_DATA) + if (event->type == RINGBUF_TYPE_DATA || rb_discarded_event(event)) cpu_buffer->entries--; rb_update_read_stamp(cpu_buffer, event); @@ -2052,9 +2092,18 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) switch (event->type) { case RINGBUF_TYPE_PADDING: - RB_WARN_ON(cpu_buffer, 1); + if (rb_null_event(event)) + RB_WARN_ON(cpu_buffer, 1); + /* + * Because the writer could be discarding every + * event it creates (which would probably be bad) + * if we were to go back to "again" then we may never + * catch up, and will trigger the warn on, or lock + * the box. Return the padding, and we will release + * the current locks, and try again. + */ rb_advance_reader(cpu_buffer); - return NULL; + return event; case RINGBUF_TYPE_TIME_EXTEND: /* Internal data, OK to advance */ @@ -2115,8 +2164,12 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) switch (event->type) { case RINGBUF_TYPE_PADDING: - rb_inc_iter(iter); - goto again; + if (rb_null_event(event)) { + rb_inc_iter(iter); + goto again; + } + rb_advance_iter(iter); + return event; case RINGBUF_TYPE_TIME_EXTEND: /* Internal data, OK to advance */ @@ -2163,10 +2216,16 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) if (!cpumask_test_cpu(cpu, buffer->cpumask)) return NULL; + again: spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_buffer_peek(buffer, cpu, ts); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + if (event && event->type == RINGBUF_TYPE_PADDING) { + cpu_relax(); + goto again; + } + return event; } @@ -2185,10 +2244,16 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_event *event; unsigned long flags; + again: spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_iter_peek(iter, ts); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + if (event && event->type == RINGBUF_TYPE_PADDING) { + cpu_relax(); + goto again; + } + return event; } @@ -2207,6 +2272,7 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) struct ring_buffer_event *event = NULL; unsigned long flags; + again: /* might be called in atomic */ preempt_disable(); @@ -2228,6 +2294,11 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) out: preempt_enable(); + if (event && event->type == RINGBUF_TYPE_PADDING) { + cpu_relax(); + goto again; + } + return event; } EXPORT_SYMBOL_GPL(ring_buffer_consume); @@ -2306,6 +2377,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; unsigned long flags; + again: spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_iter_peek(iter, ts); if (!event) @@ -2315,6 +2387,11 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) out: spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + if (event && event->type == RINGBUF_TYPE_PADDING) { + cpu_relax(); + goto again; + } + return event; } EXPORT_SYMBOL_GPL(ring_buffer_read); -- cgit v1.2.3-70-g09d2 From 2e572895bf3203e881356a4039ab0fa428ed2639 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 30 Mar 2009 14:03:19 -0400 Subject: ring-buffer: do not remove reader page from list on ring buffer free Impact: prevent possible memory leak The reader page of the ring buffer is special. Although it points into the ring buffer, it is not part of the actual buffer. It is a page used by the reader to swap with a page in the ring buffer. Once the swap is made, the new reader page is again outside the buffer. Even though the reader page points into the buffer, it is really pointing to residual data. Note, this data is used by the reader. reader page | v (prev) +---+ (next) +----------| |----------+ | +---+ | v v +---+ +---+ +---+ -->| |------->| |------->| |---> <--| |<-------| |<-------| |<--- +---+ +---+ +---+ ^ ^ ^ \ | / ------- Buffer--------- If we perform a list_del_init() on the reader page we will actually remove the last page the reader swapped with and not the reader page itself. This will cause that page to not be freed, and thus is a memory leak. Luckily, the only user of the ring buffer so far is ftrace. And ftrace will not free its ring buffer after it allocates it. There is no current possible memory leak. But once there are other users, or if ftrace dynamically creates and frees its ring buffer, then this would be a memory leak. This patch fixes the leak for future cases. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index edce2ff3894..960cbf44c84 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -563,7 +563,6 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) struct list_head *head = &cpu_buffer->pages; struct buffer_page *bpage, *tmp; - list_del_init(&cpu_buffer->reader_page->list); free_buffer_page(cpu_buffer->reader_page); list_for_each_entry_safe(bpage, tmp, head, list) { -- cgit v1.2.3-70-g09d2