From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751857AbcFNI4T (ORCPT ); Tue, 14 Jun 2016 04:56:19 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:34078 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751370AbcFNI4R (ORCPT ); Tue, 14 Jun 2016 04:56:17 -0400 Date: Tue, 14 Jun 2016 10:56:13 +0200 From: Ingo Molnar To: WANG Chao Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] sched: unlikely corrupted stack end Message-ID: <20160614085613.GC9974@gmail.com> References: <20160614064306.48035-1-wcwxyz@gmail.com> <20160614082423.6068-1-wcwxyz@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160614082423.6068-1-wcwxyz@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * WANG Chao wrote: > 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 turn task_stack_end_corrupted() into > inline function. > > Signed-off-by: WANG Chao > --- > include/linux/sched.h | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 6e42ada26345..797ca1975431 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2997,8 +2997,11 @@ 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) > + > +static inline int task_stack_end_corrupted(struct task_struct *p) > +{ > + return unlikely(*(end_of_stack(p)) != STACK_END_MAGIC); > +} The passed in pointer should be const, and the extra parentheses around the end_of_stack() call are not needed anymore (since it's now proper C code now). Thanks, Ingo