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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: 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>
This commit is contained in:
Rik van Riel 2013-04-30 19:15:35 -07:00 committed by Linus Torvalds
parent 16df3674ef
commit c460b662d5
1 changed files with 23 additions and 6 deletions
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27
ipc/sem.c
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@ -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.