linux-kernel - [PATCH v3] sched: unlikely corrupted stack end

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Date:	Wed, 15 Jun 2016 16:53:50 +0800
From:	WANG Chao <wcwxyz@...il.com>
To:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH v3] sched: unlikely corrupted stack end

unlikely() was dropped in commit ce03e4137bb2 ("sched/core: Drop
unlikely behind BUG_ON()"), but commit 29d6455178a0 ("sched: panic on
corrupted stack end") dropped BUG_ON() and called panic directly.

Now we should bring unlikely() back for branch prediction. While we're
at it, it's better and cleaner to add unlikely() to
task_stack_end_corrupted() macro.

Signed-off-by: WANG Chao <wcwxyz@...il.com>
---
 include/linux/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6e42ada26345..74a02bf30827 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2998,7 +2998,7 @@ static inline unsigned long *end_of_stack(struct task_struct *p)

 #endif
 #define task_stack_end_corrupted(task) \
-		(*(end_of_stack(task)) != STACK_END_MAGIC)
+		(unlikely(*(end_of_stack(task)) != STACK_END_MAGIC))

 static inline int object_is_on_stack(void *obj)
 {
-- 
2.9.0