linux-kernel - [tip:sched/core] sched/core: Drop unlikely behind BUG

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Message-ID: <tip-ce03e4137bb22fc560ad7a07cf4138ae2cd59f65@git.kernel.org>
Date:	Tue, 6 Oct 2015 09:17:45 -0700
From:	tip-bot for Geliang Tang <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	efault@....de, peterz@...radead.org, hpa@...or.com,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	geliangtang@....com, mingo@...nel.org, tglx@...utronix.de
Subject: [tip:sched/core] sched/core: Drop unlikely behind BUG_ON()

Commit-ID:  ce03e4137bb22fc560ad7a07cf4138ae2cd59f65
Gitweb:     http://git.kernel.org/tip/ce03e4137bb22fc560ad7a07cf4138ae2cd59f65
Author:     Geliang Tang <geliangtang@....com>
AuthorDate: Mon, 5 Oct 2015 21:26:05 +0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 6 Oct 2015 17:08:22 +0200

sched/core: Drop unlikely behind BUG_ON()

(1) For !CONFIG_BUG cases, the bug call is a no-op, so we couldn't care
    less and the change is ok.

(2) PPC and MIPS, which HAVE_ARCH_BUG_ON, do not rely on branch predictions
    as it seems to be pointless [1] and thus callers should not be trying to
    push an optimization in the first place.

(3) For CONFIG_BUG and !HAVE_ARCH_BUG_ON cases, BUG_ON() contains an
    unlikely compiler flag already.

Hence, we can drop unlikely behind BUG_ON().

  [1] http://lkml.iu.edu/hypermail/linux/kernel/1101.3/02289.html

Signed-off-by: Geliang Tang <geliangtang@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Link: http://lkml.kernel.org/r/6fa7125979f98bbeac26e268271769b6ca935c8d.1444051018.git.geliangtang@163.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fb14a01..a395db1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2971,7 +2971,7 @@ static noinline void __schedule_bug(struct task_struct *prev)
 static inline void schedule_debug(struct task_struct *prev)
 {
 #ifdef CONFIG_SCHED_STACK_END_CHECK
-	BUG_ON(unlikely(task_stack_end_corrupted(prev)));
+	BUG_ON(task_stack_end_corrupted(prev));
 #endif
 
 	if (unlikely(in_atomic_preempt_off())) {
--
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