ipc

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

Manfred Spraul authored Jul 20, 2010 and Linus Torvalds committed Jul 20, 2010

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 kamezawa.hiroyu@jp.fujitsu.com for noticing lack of the memory
barrier.

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



[akpm@linux-foundation.org: clean up kerneldoc, checkpatch warning and whitespace]
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reported-by: Luca Tettamanti <kronos.it@gmail.com>
Tested-by: Luca Tettamanti <kronos.it@gmail.com>
Reported-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Maciej Rutecki <maciej.rutecki@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c61284e9

History

c61284e9 Jul 20, 2010

History

Name	Last commit	Last update
..
Makefile
compat.c
compat_mq.c
ipc_sysctl.c
ipcns_notifier.c
mq_sysctl.c
mqueue.c
msg.c
msgutil.c
namespace.c
sem.c
shm.c
syscall.c
util.c
util.h