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Commit c728b9c8 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

ipc: simplify semtimedop/semctl_main() common error path handling 



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: default avatarDavidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 321310ce

ipc/sem.c

+14 −27
Original line number Diff line number Diff line
@@ -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 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, 


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)