From 248e7357cf8ec50bdaca68dce7c488ce843b6b93 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Wed, 14 Dec 2016 15:06:31 -0800 Subject: [PATCH] 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 Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/sem.c | 19 ++++++++++++------- 1 file 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 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, out_unlock_free: sem_unlock(sma, locknum); -out_rcu_wakeup: rcu_read_unlock(); wake_up_sem_queue_do(&tasks); out_free: -- GitLab