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authorLai Jiangshan <laijs@cn.fujitsu.com>2009-01-12 11:06:18 +0800
committerIngo Molnar <mingo@elte.hu>2009-01-21 15:21:30 +0100
commit551b4048b3d4acf15aff9fe4aed89b892c135b02 (patch)
tree5d8abe8ac236420a36164c24f98c840e89247e02
parent00f57f545afa422db3003b0d0b30a30f8de7ecb2 (diff)
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 <laijs@cn.fujitsu.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/trace/ring_buffer.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 1d6526361d0..9c1e73da4e3 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1025,12 +1025,8 @@ __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) {
@@ -1105,6 +1101,10 @@ __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;