diff options
| author | Steven Rostedt <rostedt@goodmis.org> | 2008-11-12 00:01:26 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-11-12 11:25:04 +0100 |
| commit | 642edba5f5c545772b89907cf96134c73d6073c7 (patch) | |
| tree | fe035c062474bb3163a15e3b490e2c6c5f612407 /kernel | |
| parent | d06bbd669539215405874d8fe32ab65105e6c4bb (diff) | |
| download | linux-642edba5f5c545772b89907cf96134c73d6073c7.tar.bz2 | |
ring-buffer: fix deadlock from reader_lock in read_start
Impact: deadlock fix in ring_buffer_read_start
The ring_buffer_iter_reset was called from ring_buffer_read_start
where both grabbed the reader_lock.
This patch separates out the internals of ring_buffer_iter_reset
to its own function so that both APIs may grab the reader_lock.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index c04c433fbc59..86dc353f89b9 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1475,19 +1475,9 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer) return overruns; } -/** - * ring_buffer_iter_reset - reset an iterator - * @iter: The iterator to reset - * - * Resets the iterator, so that it will start from the beginning - * again. - */ -void ring_buffer_iter_reset(struct ring_buffer_iter *iter) +static void rb_iter_reset(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; - unsigned long flags; - - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); /* Iterator usage is expected to have record disabled */ if (list_empty(&cpu_buffer->reader_page->list)) { @@ -1501,7 +1491,22 @@ void ring_buffer_iter_reset(struct ring_buffer_iter *iter) iter->read_stamp = cpu_buffer->read_stamp; else iter->read_stamp = iter->head_page->time_stamp; +} +/** + * ring_buffer_iter_reset - reset an iterator + * @iter: The iterator to reset + * + * Resets the iterator, so that it will start from the beginning + * again. + */ +void ring_buffer_iter_reset(struct ring_buffer_iter *iter) +{ + struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; + unsigned long flags; + + spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + rb_iter_reset(iter); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } @@ -1957,7 +1962,7 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu) spin_lock_irqsave(&cpu_buffer->reader_lock, flags); __raw_spin_lock(&cpu_buffer->lock); - ring_buffer_iter_reset(iter); + rb_iter_reset(iter); __raw_spin_unlock(&cpu_buffer->lock); spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |