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Commit 4091fd94 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

ipc: move the rcu_read_lock() from sem_lock_and_putref() into callers 



This is another ipc semaphore locking cleanup, trying to make the
locking more straightforward.  We move the rcu read locking into the
callers of sem_lock_and_putref(), which in general means that we now
mostly do the rcu_read_lock() and rcu_read_unlock() in the same
function.

Mostly.  We still have the ipc_addid/newary/freeary mess, and things
like ipcctl_pre_down_nolock().

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 73b29505

ipc/sem.c

+3 −2
Original line number Diff line number Diff line
@@ -322,7 +322,6 @@ static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns 


static inline void sem_lock_and_putref(struct sem_array *sma)

{

	rcu_read_lock();

	sem_lock(sma, NULL, -1);

	ipc_rcu_putref(sma);

}
@@ -1117,6 +1116,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, 
				return -ENOMEM;

			}



			rcu_read_lock();

			sem_lock_and_putref(sma);

			if (sma->sem_perm.deleted) {

				sem_unlock(sma, -1);
@@ -1166,6 +1166,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, 
				goto out_free;

			}

		}

		rcu_read_lock();

		sem_lock_and_putref(sma);

		if (sma->sem_perm.deleted) {

			sem_unlock(sma, -1);
@@ -1451,7 +1452,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) 
	}



	/* step 3: Acquire the lock on semaphore array */

	/* This also does the rcu_read_lock() */

	rcu_read_lock();

	sem_lock_and_putref(sma);

	if (sma->sem_perm.deleted) {

		sem_unlock(sma, -1);