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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2009-11-03 19:42:45 +0800 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2009-11-04 00:04:20 -0500 |
| commit | f7112949f6a4cd6883d66c882d568c2197321de6 (patch) | |
| tree | 2982044acfce5f1e422be2fd7467d2f1177c5159 /kernel/trace/ring_buffer.c | |
| parent | 6d3f1e12f46a2f9a1bb7e7aa433df8dd31ce5647 (diff) | |
| download | lwn-f7112949f6a4cd6883d66c882d568c2197321de6.tar.gz lwn-f7112949f6a4cd6883d66c882d568c2197321de6.zip | |
ring-buffer: Synchronize resizing buffer with reader lock
We got a sudden panic when we reduced the size of the
ringbuffer.
We can reproduce the panic by the following steps:
echo 1 > events/sched/enable
cat trace_pipe > /dev/null &
while ((1))
do
echo 12000 > buffer_size_kb
echo 512 > buffer_size_kb
done
(not more than 5 seconds, panic ...)
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4AF01735.9060409@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 3ffa502fb243..5dd017fea6f5 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1193,6 +1193,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) atomic_inc(&cpu_buffer->record_disabled); synchronize_sched(); + spin_lock_irq(&cpu_buffer->reader_lock); rb_head_page_deactivate(cpu_buffer); for (i = 0; i < nr_pages; i++) { @@ -1207,6 +1208,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) return; rb_reset_cpu(cpu_buffer); + spin_unlock_irq(&cpu_buffer->reader_lock); rb_check_pages(cpu_buffer); |