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

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>

diff --git a/ipc/sem.c b/ipc/sem.c
index 10b94bc59d4a5ffaa85a89152ac02a1f806db054..b33dd98fde69397efc3225653e567e4d3daa9fe4 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -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: