ring-buffer: prevent false positive warning

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Impact: eliminate false WARN_ON message

If an interrupt goes off after the setting of the local variable
tail_page and before incrementing the write index of that page,
the interrupt could push the commit forward to the next page.

Later a check is made to see if interrupts pushed the buffer around
the entire ring buffer by comparing the next page to the last commited
page. This can produce a false positive if the interrupt had pushed
the commit page forward as stated above.

Thanks to Jiaying Zhang for finding this race.

Reported-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

...

This commit is contained in:

Steven Rostedt 2008-12-23 11:32:25 -05:00 • committed by Ingo Molnar

parent a8ccf1d6f6

commit 98db8df777

1 changed files with 5 additions and 2 deletions

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kernel/trace/ring_buffer.c

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