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| author | Davidlohr Bueso <dave@stgolabs.net> | 2016-12-14 15:06:31 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-14 16:04:08 -0800 |
| commit | 248e7357cf8ec50bdaca68dce7c488ce843b6b93 (patch) | |
| tree | 54ea60ba6f92ee99014c0b565ab87150eb930067 /ipc/sem.c | |
| parent | 7a5c8b57cec93196b3e84e3cad2ff81ae0faed78 (diff) | |
| download | lwn-248e7357cf8ec50bdaca68dce7c488ce843b6b93.tar.gz lwn-248e7357cf8ec50bdaca68dce7c488ce843b6b93.zip | |
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>
Diffstat (limited to 'ipc/sem.c')
| -rw-r--r-- | ipc/sem.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index 10b94bc59d4a..b33dd98fde69 100644 --- 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: |