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ring_buffer: reset write when reserve buffer fail

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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>
This commit is contained in:
Lai Jiangshan 2009-01-12 11:06:18 +08:00 committed by Ingo Molnar
parent 428aee1460
commit 6f3b34402e
1 changed files with 5 additions and 5 deletions
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10
kernel/trace/ring_buffer.c
View file

@ -1017,12 +1017,8 @@ __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) {
@ -1097,6 +1093,10 @@ __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;