ipc: move the rcu_read_lock() from sem_lock_and_putref() into callers (4091fd94) · Commits · 戴 / test

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:

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

+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);

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