Commit 248e7357 authored Dec 14, 2016 by Davidlohr Bueso Committed by Linus Torvalds Dec 14, 2016

ipc/sem: do not call wake_sem_queue_do() prematurely ... as this call should...

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>

parent 7a5c8b57

ipc/sem.c

+12 −7

Original line number	Diff line number	Diff line
		@@ -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: