From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756647AbZDTUo5 (ORCPT ); Mon, 20 Apr 2009 16:44:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753989AbZDTUos (ORCPT ); Mon, 20 Apr 2009 16:44:48 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:47631 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753476AbZDTUor (ORCPT ); Mon, 20 Apr 2009 16:44:47 -0400 Date: Mon, 20 Apr 2009 16:44:46 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Frederic Weisbecker cc: Ingo Molnar , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH 0/4] [GIT PULL] tracing: recursion and compile fixes In-Reply-To: <20090420203347.GD5974@nowhere> Message-ID: References: <20090420173819.957332585@goodmis.org> <20090420175533.GA22449@elte.hu> <20090420192803.GA25629@elte.hu> <20090420194542.GB5974@nowhere> <20090420203347.GD5974@nowhere> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 20 Apr 2009, Frederic Weisbecker wrote: > > > > > > > Hmm, doesn't the trace wakeup test if the runqueue lock is locked or not? > > > > -- Steve > > > > > Hmm, yes it does but that's not the first time we meet this problem > (sched switch event tracing recursions by the past). So either the > test doesn't work well or this is about another lock that > wake_up_common takes... Ug, it is the task's rq lock. Not the current rq lock. wakeup takes the runqueue lock of the task. The "runqueue_is_locked" only tests the lock of current CPU, which is not what we can have. Thus, the function tracer (gag, and probably the event tracing!) should not call wakeups. -- Steve