From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752467AbcFNKRv (ORCPT ); Tue, 14 Jun 2016 06:17:51 -0400 Received: from mail-pa0-f67.google.com ([209.85.220.67]:35681 "EHLO mail-pa0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751863AbcFNKRh convert rfc822-to-8bit (ORCPT ); Tue, 14 Jun 2016 06:17:37 -0400 Subject: Re: [PATCH v2] sched: unlikely corrupted stack end Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Content-Type: text/plain; charset=gb2312 From: WANG Chao In-Reply-To: <20160614085613.GC9974@gmail.com> Date: Tue, 14 Jun 2016 18:17:29 +0800 Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: References: <20160614064306.48035-1-wcwxyz@gmail.com> <20160614082423.6068-1-wcwxyz@gmail.com> <20160614085613.GC9974@gmail.com> To: Ingo Molnar X-Mailer: Apple Mail (2.3124) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 在 2016年6月14日，下午4:56，Ingo Molnar 写道： > > > * 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). end_of_stack() will discard const and cause an compiler warning. Should I add const to end_of_stack()?