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 <[email protected]>
--- 25/kernel/signal.c~1_LTS_RCU 2008-02-15 20:34:32.000000000 +0300
+++ 25/kernel/signal.c 2008-02-18 18:35:04.000000000 +0300
@@ -978,13 +978,11 @@ int fastcall __fatal_signal_pending(stru
}
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))
@@ -995,6 +993,7 @@ struct sighand_struct *lock_task_sighand
break;
spin_unlock_irqrestore(&sighand->siglock, *flags);
}
+ rcu_read_unlock();
return sighand;
}