lock_task_sighand: add rcu lock/unlock
Most of the callers of lock_task_sighand() doesn't actually need rcu_lock().
lock_task_sighand() needs it only to safely play with tsk->sighand, it can
take the lock itself.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/signal.c b/kernel/signal.c
index 29aca40..4a45bac 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -971,13 +971,11 @@
}
EXPORT_SYMBOL(__fatal_signal_pending);
-/*
- * Must be called under rcu_read_lock() or with tasklist_lock read-held.
- */
struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
{
struct sighand_struct *sighand;
+ rcu_read_lock();
for (;;) {
sighand = rcu_dereference(tsk->sighand);
if (unlikely(sighand == NULL))
@@ -988,6 +986,7 @@
break;
spin_unlock_irqrestore(&sighand->siglock, *flags);
}
+ rcu_read_unlock();
return sighand;
}