ipc,sem: open code and rename sem_lock (c460b662) · Commits · 戴 / test

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:

Rik van Riel <riel@redhat.com> Acked-by:

Davidlohr 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:

Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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 @@ sleep_again:
		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.

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