ipc: simplify semtimedop/semctl_main() common error path handling
Linus Torvalds [Sat, 4 May 2013 18:04:29 +0000 (11:04 -0700)]
With various straight RCU lock/unlock movements, one common exit path
pattern had become

rcu_read_unlock();
goto out_wakeup;

and in fact there were no cases where we wanted to exit to out_wakeup
_without_ releasing the RCU read lock.

So replace that pattern with "goto out_rcu_wakeup", and remove the old
out_wakeup.

Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/sem.c

index 8486a5b..f2151ba 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1077,17 +1077,12 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
        nsems = sma->sem_nsems;
 
        err = -EACCES;
-       if (ipcperms(ns, &sma->sem_perm,
-                       cmd == SETALL ? S_IWUGO : S_IRUGO)) {
-               rcu_read_unlock();
-               goto out_wakeup;
-       }
+       if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO))
+               goto out_rcu_wakeup;
 
        err = security_sem_semctl(sma, cmd);
-       if (err) {
-               rcu_read_unlock();
-               goto out_wakeup;
-       }
+       if (err)
+               goto out_rcu_wakeup;
 
        err = -EACCES;
        switch (cmd) {
@@ -1188,10 +1183,8 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
        /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */
        }
        err = -EINVAL;
-       if (semnum < 0 || semnum >= nsems) {
-               rcu_read_unlock();
-               goto out_wakeup;
-       }
+       if (semnum < 0 || semnum >= nsems)
+               goto out_rcu_wakeup;
 
        sem_lock(sma, NULL, -1);
        curr = &sma->sem_base[semnum];
@@ -1213,8 +1206,8 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 
 out_unlock:
        sem_unlock(sma, -1);
+out_rcu_wakeup:
        rcu_read_unlock();
-out_wakeup:
        wake_up_sem_queue_do(&tasks);
 out_free:
        if(sem_io != fast_sem_io)
@@ -1585,22 +1578,16 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
        }
 
        error = -EFBIG;
-       if (max >= sma->sem_nsems) {
-               rcu_read_unlock();
-               goto out_wakeup;
-       }
+       if (max >= sma->sem_nsems)
+               goto out_rcu_wakeup;
 
        error = -EACCES;
-       if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
-               rcu_read_unlock();
-               goto out_wakeup;
-       }
+       if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
+               goto out_rcu_wakeup;
 
        error = security_sem_semop(sma, sops, nsops, alter);
-       if (error) {
-               rcu_read_unlock();
-               goto out_wakeup;
-       }
+       if (error)
+               goto out_rcu_wakeup;
 
        /*
         * semid identifiers are not unique - find_alloc_undo may have
@@ -1718,8 +1705,8 @@ sleep_again:
 
 out_unlock_free:
        sem_unlock(sma, locknum);
+out_rcu_wakeup:
        rcu_read_unlock();
-out_wakeup:
        wake_up_sem_queue_do(&tasks);
 out_free:
        if(sops != fast_sops)