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Commit c460b662 authored by Rik van Riel's avatar Rik van Riel Committed by Linus Torvalds
Browse files

ipc,sem: open code and rename sem_lock 



Rename sem_lock() to sem_obtain_lock(), so we can introduce a sem_lock()
later that only locks the sem_array and does nothing else.

Open code the locking from ipc_lock() in sem_obtain_lock() so we can
introduce finer grained locking for the sem_array in the next patch.

[akpm@linux-foundation.org: propagate the ipc_obtain_object() errno out of sem_obtain_lock()]
Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarDavidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 16df3674

ipc/sem.c

+23 −6
Original line number Diff line number Diff line
@@ -194,14 +194,31 @@ void __init sem_init (void) 
 * sem_lock_(check_) routines are called in the paths where the rw_mutex

 * is not held.

 */

static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)

static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns, int id)

{

	struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);

	struct kern_ipc_perm *ipcp;

	struct sem_array *sma;



	if (IS_ERR(ipcp))

		return (struct sem_array *)ipcp;

	rcu_read_lock();

	ipcp = ipc_obtain_object(&sem_ids(ns), id);

	if (IS_ERR(ipcp)) {

		sma = ERR_CAST(ipcp);

		goto err;

	}



	spin_lock(&ipcp->lock);



	/* ipc_rmid() may have already freed the ID while sem_lock

	 * was spinning: verify that the structure is still valid

	 */

	if (!ipcp->deleted)

		return container_of(ipcp, struct sem_array, sem_perm);



	spin_unlock(&ipcp->lock);

	sma = ERR_PTR(-EINVAL);

err:

	rcu_read_unlock();

	return sma;

}



static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id)
@@ -1593,7 +1610,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, 
		goto out_free;

	}



	sma = sem_lock(ns, semid);

	sma = sem_obtain_lock(ns, semid);



	/*

	 * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing.