From 9d5f09a424a67ddb959829894efb4c71cbf6d600 Mon Sep 17 00:00:00 2001 From: "Alan D. Brunelle" Date: Tue, 27 May 2008 14:54:41 +0200 Subject: Added in MESSAGE notes for blktraces Allows messages to be inserted into blktrace streams. Signed-off-by: Alan D. Brunelle Signed-off-by: Jens Axboe --- block/blktrace.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'block/blktrace.c') diff --git a/block/blktrace.c b/block/blktrace.c index b2cbb4e5d76..20e11f354f1 100644 --- a/block/blktrace.c +++ b/block/blktrace.c @@ -75,6 +75,20 @@ static void trace_note_time(struct blk_trace *bt) local_irq_restore(flags); } +void __trace_note_message(struct blk_trace *bt, const char *fmt, ...) +{ + int n; + va_list args; + static char bt_msg_buf[BLK_TN_MAX_MSG]; + + va_start(args, fmt); + n = vscnprintf(bt_msg_buf, BLK_TN_MAX_MSG, fmt, args); + va_end(args); + + trace_note(bt, 0, BLK_TN_MESSAGE, bt_msg_buf, n); +} +EXPORT_SYMBOL_GPL(__trace_note_message); + static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector, pid_t pid) { -- cgit v1.2.3-70-g09d2 From 64565911cdb57c2f512a9715b985b5617402cc67 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 28 May 2008 14:45:33 +0200 Subject: block: make blktrace use per-cpu buffers for message notes Currently it uses a single static char array, but that risks being corrupted when multiple users issue message notes at the same time. Make the buffers dynamically allocated when the trace is setup and make them per-cpu instead. The default max message size of 1k is also very large, the interface is mainly for small text notes. So shrink it to 128 bytes. Signed-off-by: Jens Axboe --- block/blktrace.c | 15 ++++++++++++--- include/linux/blktrace_api.h | 3 ++- 2 files changed, 14 insertions(+), 4 deletions(-) (limited to 'block/blktrace.c') diff --git a/block/blktrace.c b/block/blktrace.c index 20e11f354f1..7ae87cc4a16 100644 --- a/block/blktrace.c +++ b/block/blktrace.c @@ -79,13 +79,16 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...) { int n; va_list args; - static char bt_msg_buf[BLK_TN_MAX_MSG]; + char *buf; + preempt_disable(); + buf = per_cpu_ptr(bt->msg_data, smp_processor_id()); va_start(args, fmt); - n = vscnprintf(bt_msg_buf, BLK_TN_MAX_MSG, fmt, args); + n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args); va_end(args); - trace_note(bt, 0, BLK_TN_MESSAGE, bt_msg_buf, n); + trace_note(bt, 0, BLK_TN_MESSAGE, buf, n); + preempt_enable(); } EXPORT_SYMBOL_GPL(__trace_note_message); @@ -246,6 +249,7 @@ static void blk_trace_cleanup(struct blk_trace *bt) debugfs_remove(bt->dropped_file); blk_remove_tree(bt->dir); free_percpu(bt->sequence); + free_percpu(bt->msg_data); kfree(bt); } @@ -360,6 +364,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, if (!bt->sequence) goto err; + bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG); + if (!bt->msg_data) + goto err; + ret = -ENOENT; dir = blk_create_tree(buts->name); if (!dir) @@ -406,6 +414,7 @@ err: if (bt->dropped_file) debugfs_remove(bt->dropped_file); free_percpu(bt->sequence); + free_percpu(bt->msg_data); if (bt->rchan) relay_close(bt->rchan); kfree(bt); diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h index b7cd8f1eedb..e3ef903aae8 100644 --- a/include/linux/blktrace_api.h +++ b/include/linux/blktrace_api.h @@ -121,6 +121,7 @@ struct blk_trace { int trace_state; struct rchan *rchan; unsigned long *sequence; + unsigned char *msg_data; u16 act_mask; u64 start_lba; u64 end_lba; @@ -172,7 +173,7 @@ extern void __trace_note_message(struct blk_trace *, const char *fmt, ...); if (unlikely(bt)) \ __trace_note_message(bt, fmt, ##__VA_ARGS__); \ } while (0) -#define BLK_TN_MAX_MSG 1024 +#define BLK_TN_MAX_MSG 128 /** * blk_add_trace_rq - Add a trace for a request oriented action -- cgit v1.2.3-70-g09d2 From 14a73f54798f39854e521fb596da7d50b7566bbd Mon Sep 17 00:00:00 2001 From: Carl Henrik Lunde Date: Thu, 12 Jun 2008 20:13:58 +0200 Subject: block: disable IRQs until data is written to relay channel As we may run relay_reserve from interrupt context we must always disable IRQs. This is because a call to relay_reserve may expose previously written data to use space. Updated new message code and an old but related comment. Signed-off-by: Carl Henrik Lunde Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds --- block/blktrace.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'block/blktrace.c') diff --git a/block/blktrace.c b/block/blktrace.c index 7ae87cc4a16..8d3a2778026 100644 --- a/block/blktrace.c +++ b/block/blktrace.c @@ -79,16 +79,17 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...) { int n; va_list args; + unsigned long flags; char *buf; - preempt_disable(); + local_irq_save(flags); buf = per_cpu_ptr(bt->msg_data, smp_processor_id()); va_start(args, fmt); n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args); va_end(args); trace_note(bt, 0, BLK_TN_MESSAGE, buf, n); - preempt_enable(); + local_irq_restore(flags); } EXPORT_SYMBOL_GPL(__trace_note_message); @@ -158,10 +159,7 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, /* * A word about the locking here - we disable interrupts to reserve * some space in the relay per-cpu buffer, to prevent an irq - * from coming in and stepping on our toes. Once reserved, it's - * enough to get preemption disabled to prevent read of this data - * before we are through filling it. get_cpu()/put_cpu() does this - * for us + * from coming in and stepping on our toes. */ local_irq_save(flags); -- cgit v1.2.3-70-g09d2