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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: 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>
This commit is contained in:
Linus Torvalds 2013-05-04 10:13:40 -07:00
parent 73b29505c3
commit 4091fd942e
1 changed files with 3 additions and 2 deletions
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5
ipc/sem.c
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@ -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) static inline void sem_lock_and_putref(struct sem_array *sma)
{ {
rcu_read_lock();
sem_lock(sma, NULL, -1); sem_lock(sma, NULL, -1);
ipc_rcu_putref(sma); ipc_rcu_putref(sma);
} }
@ -1117,6 +1116,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
return -ENOMEM; return -ENOMEM;
} }
rcu_read_lock();
sem_lock_and_putref(sma); sem_lock_and_putref(sma);
if (sma->sem_perm.deleted) { if (sma->sem_perm.deleted) {
sem_unlock(sma, -1); sem_unlock(sma, -1);
@ -1166,6 +1166,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
goto out_free; goto out_free;
} }
} }
rcu_read_lock();
sem_lock_and_putref(sma); sem_lock_and_putref(sma);
if (sma->sem_perm.deleted) { if (sma->sem_perm.deleted) {
sem_unlock(sma, -1); 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 */ /* step 3: Acquire the lock on semaphore array */
/* This also does the rcu_read_lock() */ rcu_read_lock();
sem_lock_and_putref(sma); sem_lock_and_putref(sma);
if (sma->sem_perm.deleted) { if (sma->sem_perm.deleted) {
sem_unlock(sma, -1); sem_unlock(sma, -1);