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ipc/sem: do not call wake_sem_queue_do() prematurely ... as this call should obviously be paired with its _prepare() 

counterpart.  At least whenever possible, as there is no harm in calling
it bogusly as we do now in a few places.  Immediate error semop(2) paths
that are far from ever having the task block can be simplified and avoid
a few unnecessary loads on their way out of the call as it is not deeply
nested.

Link: http://lkml.kernel.org/r/1474225896-10066-2-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zero-colors
Davidlohr Bueso 2016-12-14 15:06:31 -08:00 committed by Linus Torvalds
parent 7a5c8b57ce
commit 248e7357cf
1 changed files with 12 additions and 7 deletions
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19
ipc/sem.c
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@ -1887,16 +1887,22 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
}
error = -EFBIG;
if (max >= sma->sem_nsems)
goto out_rcu_wakeup;
if (max >= sma->sem_nsems) {
rcu_read_unlock();
goto out_free;
}
error = -EACCES;
if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
goto out_rcu_wakeup;
if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
rcu_read_unlock();
goto out_free;
}
error = security_sem_semop(sma, sops, nsops, alter);
if (error)
goto out_rcu_wakeup;
if (error) {
rcu_read_unlock();
goto out_free;
}
error = -EIDRM;
locknum = sem_lock(sma, sops, nsops);
@ -2039,7 +2045,6 @@ sleep_again:
out_unlock_free:
sem_unlock(sma, locknum);
out_rcu_wakeup:
rcu_read_unlock();
wake_up_sem_queue_do(&tasks);
out_free: