[PATCH] Fix semundo lock leakage
Ingo Molnar authored
semundo->lock can leak if semundo->refcount goes from 2 to 1 while
another thread has it locked.  This causes major problems for PREEMPT
kernels.

The simplest fix for now is to undo the single-thread optimization.

This bug was found via relentless testing by Dominik Karall.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
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