Re: ipc,sem: sysv semaphore scalability
From: Rik van Riel
Date: Sun Mar 31 2013 - 09:45:53 EST
On 03/31/2013 01:01 AM, Davidlohr Bueso wrote:
diff --git a/ipc/sem.c b/ipc/sem.c
index f257afe..74cedfe 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1867,8 +1867,7 @@ void exit_sem(struct task_struct *tsk)
struct sem_array *sma;
struct sem_undo *un;
struct list_head tasks;
- int semid;
- int i;
+ int semid, i;
rcu_read_lock();
un = list_entry_rcu(ulp->list_proc.next,
@@ -1884,12 +1883,13 @@ void exit_sem(struct task_struct *tsk)
}
sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, un->semid);
Should we use "semid" here, like Linus suggested, instead of "un->semid"?
- sem_lock(sma, NULL, -1);
-
/* exit_sem raced with IPC_RMID, nothing to do */
- if (IS_ERR(sma))
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
continue;
+ }
+ sem_lock(sma, NULL, -1);
un = __lookup_undo(ulp, semid);
if (un == NULL) {
/* exit_sem raced with IPC_RMID+semget() that created
--
All rights reversed.
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