ipc/sem.c: bugfix for semop() not reporting successful operation

The last change to improve the scalability moved the actual wake-up out of
the section that is protected by spin_lock(sma->sem_perm.lock).

This means that IN_WAKEUP can be in queue.status even when the spinlock is
acquired by the current task.  Thus the same loop that is performed when
queue.status is read without the spinlock acquired must be performed when
the spinlock is acquired.

Thanks to [email protected] for noticing lack of the memory
barrier.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=16255

[[email protected]: clean up kerneldoc, checkpatch warning and whitespace]
Signed-off-by: Manfred Spraul <[email protected]>
Reported-by: Luca Tettamanti <[email protected]>
Tested-by: Luca Tettamanti <[email protected]>
Reported-by: Christoph Lameter <[email protected]>
Cc: Maciej Rutecki <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions