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-rw-r--r--kernel/trace/ring_buffer.c65
1 files changed, 52 insertions, 13 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b979426d16c..ce8514feedc 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -460,9 +460,10 @@ struct ring_buffer_per_cpu {
unsigned long lost_events;
unsigned long last_overrun;
local_t entries_bytes;
- local_t commit_overrun;
- local_t overrun;
local_t entries;
+ local_t overrun;
+ local_t commit_overrun;
+ local_t dropped_events;
local_t committing;
local_t commits;
unsigned long read;
@@ -1396,6 +1397,8 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer)
struct list_head *head_page_with_bit;
head_page = &rb_set_head_page(cpu_buffer)->list;
+ if (!head_page)
+ break;
prev_page = head_page->prev;
first_page = pages->next;
@@ -1820,7 +1823,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta)
}
/**
- * ring_buffer_update_event - update event type and data
+ * rb_update_event - update event type and data
* @event: the even to update
* @type: the type of event
* @length: the size of the event field in the ring buffer
@@ -2155,8 +2158,10 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
* If we are not in overwrite mode,
* this is easy, just stop here.
*/
- if (!(buffer->flags & RB_FL_OVERWRITE))
+ if (!(buffer->flags & RB_FL_OVERWRITE)) {
+ local_inc(&cpu_buffer->dropped_events);
goto out_reset;
+ }
ret = rb_handle_head_page(cpu_buffer,
tail_page,
@@ -2720,8 +2725,8 @@ EXPORT_SYMBOL_GPL(ring_buffer_discard_commit);
* and not the length of the event which would hold the header.
*/
int ring_buffer_write(struct ring_buffer *buffer,
- unsigned long length,
- void *data)
+ unsigned long length,
+ void *data)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event;
@@ -2929,12 +2934,12 @@ rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer)
* @buffer: The ring buffer
* @cpu: The per CPU buffer to read from.
*/
-unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
+u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
{
unsigned long flags;
struct ring_buffer_per_cpu *cpu_buffer;
struct buffer_page *bpage;
- unsigned long ret;
+ u64 ret = 0;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return 0;
@@ -2949,7 +2954,8 @@ unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
bpage = cpu_buffer->reader_page;
else
bpage = rb_set_head_page(cpu_buffer);
- ret = bpage->page->time_stamp;
+ if (bpage)
+ ret = bpage->page->time_stamp;
raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
return ret;
@@ -2995,7 +3001,8 @@ unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu)
EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu);
/**
- * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer
+ * ring_buffer_overrun_cpu - get the number of overruns caused by the ring
+ * buffer wrapping around (only if RB_FL_OVERWRITE is on).
* @buffer: The ring buffer
* @cpu: The per CPU buffer to get the number of overruns from
*/
@@ -3015,7 +3022,9 @@ unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu)
EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu);
/**
- * ring_buffer_commit_overrun_cpu - get the number of overruns caused by commits
+ * ring_buffer_commit_overrun_cpu - get the number of overruns caused by
+ * commits failing due to the buffer wrapping around while there are uncommitted
+ * events, such as during an interrupt storm.
* @buffer: The ring buffer
* @cpu: The per CPU buffer to get the number of overruns from
*/
@@ -3036,6 +3045,28 @@ ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu)
EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu);
/**
+ * ring_buffer_dropped_events_cpu - get the number of dropped events caused by
+ * the ring buffer filling up (only if RB_FL_OVERWRITE is off).
+ * @buffer: The ring buffer
+ * @cpu: The per CPU buffer to get the number of overruns from
+ */
+unsigned long
+ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu)
+{
+ struct ring_buffer_per_cpu *cpu_buffer;
+ unsigned long ret;
+
+ if (!cpumask_test_cpu(cpu, buffer->cpumask))
+ return 0;
+
+ cpu_buffer = buffer->buffers[cpu];
+ ret = local_read(&cpu_buffer->dropped_events);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu);
+
+/**
* ring_buffer_entries - get the number of entries in a buffer
* @buffer: The ring buffer
*
@@ -3260,6 +3291,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
* Splice the empty reader page into the list around the head.
*/
reader = rb_set_head_page(cpu_buffer);
+ if (!reader)
+ goto out;
cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next);
cpu_buffer->reader_page->list.prev = reader->list.prev;
@@ -3778,12 +3811,17 @@ void
ring_buffer_read_finish(struct ring_buffer_iter *iter)
{
struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
+ unsigned long flags;
/*
* Ring buffer is disabled from recording, here's a good place
- * to check the integrity of the ring buffer.
+ * to check the integrity of the ring buffer.
+ * Must prevent readers from trying to read, as the check
+ * clears the HEAD page and readers require it.
*/
+ raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
rb_check_pages(cpu_buffer);
+ raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
atomic_dec(&cpu_buffer->record_disabled);
atomic_dec(&cpu_buffer->buffer->resize_disabled);
@@ -3864,9 +3902,10 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
local_set(&cpu_buffer->reader_page->page->commit, 0);
cpu_buffer->reader_page->read = 0;
- local_set(&cpu_buffer->commit_overrun, 0);
local_set(&cpu_buffer->entries_bytes, 0);
local_set(&cpu_buffer->overrun, 0);
+ local_set(&cpu_buffer->commit_overrun, 0);
+ local_set(&cpu_buffer->dropped_events, 0);
local_set(&cpu_buffer->entries, 0);
local_set(&cpu_buffer->committing, 0);
local_set(&cpu_buffer->commits, 0);