From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758651Ab1ELUlE (ORCPT ); Thu, 12 May 2011 16:41:04 -0400 Received: from mail-gx0-f174.google.com ([209.85.161.174]:60690 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758600Ab1ELUlB (ORCPT ); Thu, 12 May 2011 16:41:01 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=SIvsIln1+WTIeXSSSnML7BgOwI+UxKcBpRAFqvivKCtX8rFkoed1kAOVEhuoZhWXf8 DQSbng9IW97Z7bkbNKM9YWupRbVesy2uax1EPUzRfOagsOdrzaKXSotYcUNMpOeL5E6y 5I31WGG0d+vIgTS3YHfe8RCjUkb3/V08CQjX8= Date: Thu, 12 May 2011 22:40:54 +0200 From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Peter Zijlstra , "H. Peter Anvin" , Thomas Gleixner , Steven Rostedt Subject: Re: [PATCH 2/2] x86: Make the x86-64 stacktrace code safely callable from scheduler Message-ID: <20110512204051.GD7410@nowhere> References: <1305232326-9804-1-git-send-email-fweisbec@gmail.com> <1305232326-9804-3-git-send-email-fweisbec@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1305232326-9804-3-git-send-email-fweisbec@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 12, 2011 at 10:32:06PM +0200, Frederic Weisbecker wrote: > Avoid potential scheduler recursion and deadlock from the > stacktrace code by avoiding rescheduling when we re-enable > preemption. > > This robustifies some scheduler trace events like sched switch > when they are used to produce callchains in perf or ftrace. Actually trace events are already safe because they already disable preemption so callchains won't call schedule() there. But still let's be careful, we never know how stacktrace can be used.