Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core fixes from Thomas Gleixner:
 "A small set of core updates:

   - Make objtool cope with GCC8 oddities some more

   - Remove a stale local_irq_save/restore sequence in the signal code
     along with the stale comment in the RCU code. The underlying issue
     which led to this has been solved long time ago, but nobody cared
     to cleanup the hackarounds"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  signal: Remove no longer required irqsave/restore
  rcu: Update documentation of rcu_read_unlock()
  objtool: Fix GCC 8 cold subfunction detection for aliased functions

1 files changed, 7 insertions, 17 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 0f865d67415d..8d8a940422a8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1244,19 +1244,12 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
 {
 	struct sighand_struct *sighand;
 
+	rcu_read_lock();
 	for (;;) {
-		/*
-		 * Disable interrupts early to avoid deadlocks.
-		 * See rcu_read_unlock() comment header for details.
-		 */
-		local_irq_save(*flags);
-		rcu_read_lock();
 		sighand = rcu_dereference(tsk->sighand);
-		if (unlikely(sighand == NULL)) {
-			rcu_read_unlock();
-			local_irq_restore(*flags);
+		if (unlikely(sighand == NULL))
 			break;
-		}
+
 		/*
 		 * This sighand can be already freed and even reused, but
 		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
@@ -1268,15 +1261,12 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
 		 * __exit_signal(). In the latter case the next iteration
 		 * must see ->sighand == NULL.
 		 */
-		spin_lock(&sighand->siglock);
-		if (likely(sighand == tsk->sighand)) {
-			rcu_read_unlock();
+		spin_lock_irqsave(&sighand->siglock, *flags);
+		if (likely(sighand == tsk->sighand))
 			break;
-		}
-		spin_unlock(&sighand->siglock);
-		rcu_read_unlock();
-		local_irq_restore(*flags);
+		spin_unlock_irqrestore(&sighand->siglock, *flags);
 	}
+	rcu_read_unlock();
 
 	return sighand;
 }