From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758265Ab0DPDwp (ORCPT ); Thu, 15 Apr 2010 23:52:45 -0400 Received: from mail-pv0-f174.google.com ([74.125.83.174]:49155 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757702Ab0DPDwn convert rfc822-to-8bit (ORCPT ); Thu, 15 Apr 2010 23:52:43 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=Q2RqHpD17RxEKj8oAhQOkY6kLM/ZsetJKPYNtI8CMcug79L0i5A1m3Ioo/6IuJJoIF 3UAbZ7IgRXbE0QPwaqSpb5AV6Y7nJnsqTWBW5ivvW+NT2I5OZa9ug/aCdcO56DEy1j7f OhXtf8WSLicoOCRjfGDVJd8ODgVDC5TdibYUE= MIME-Version: 1.0 In-Reply-To: References: <1271262016-18650-1-git-send-email-chase.douglas@canonical.com> <1271262016-18650-3-git-send-email-chase.douglas@canonical.com> <20100415210357.GG5069@nowhere> Date: Thu, 15 Apr 2010 20:52:42 -0700 X-Google-Sender-Auth: 10a6b34a93aa49b6 Message-ID: Subject: Re: [PATCH 3/3] Stop tracing on a schedule bug From: Chase Douglas To: Thomas Gleixner Cc: Frederic Weisbecker , linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , Randy Dunlap Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 15, 2010 at 4:50 PM, Thomas Gleixner wrote: > On Thu, 15 Apr 2010, Chase Douglas wrote: >> On Thu, Apr 15, 2010 at 4:01 PM, Thomas Gleixner wrote: >> > On Thu, 15 Apr 2010, Chase Douglas wrote: >> >> On Thu, Apr 15, 2010 at 2:03 PM, Frederic Weisbecker wrote: >> >> > On Wed, Apr 14, 2010 at 12:20:16PM -0400, Chase Douglas wrote: >> >> >> This change adds a tracing_off_event() call to stop tracing on schedule >> >> >> bugs unless tracing_off=none was specified on the commandline. >> >> >> >> >> >> Signed-off-by: Chase Douglas >> >> >> --- >> >> >>  kernel/sched.c |    2 ++ >> >> >>  1 files changed, 2 insertions(+), 0 deletions(-) >> >> >> >> >> >> diff --git a/kernel/sched.c b/kernel/sched.c >> >> >> index 6af210a..439f036 100644 >> >> >> --- a/kernel/sched.c >> >> >> +++ b/kernel/sched.c >> >> >> @@ -3590,6 +3590,8 @@ static noinline void __schedule_bug(struct task_struct *prev) >> >> >>  { >> >> >>       struct pt_regs *regs = get_irq_regs(); >> >> >> >> >> >> +     tracing_off_event(TRACE_EVENT_BUG); >> >> >> + >> >> >>       printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", >> >> >>               prev->comm, prev->pid, preempt_count()); >> >> > >> >> > >> >> > >> >> > I would rather call that a TRACE_EVENT_WARN as this is what happens: we >> >> > warn but we continue. >> >> >> >> I tend to think of the TRACE_EVENT_* as an indication of severity and >> >> whether we want to stop the trace by default. From a distro >> >> standpoint, the likelihood that we want to continue tracing after a >> >> __schedule_bug is pretty low. It's easiest if we don't have to tell >> > >> > Well, scheduling while atomic is a BUG, but one of the category which >> > allows the kernel to continue. So in fact it's treated like a WARN_ON. >> > So the tracing_off_event() qualifier should be *_WARN. >> > >> > That's independent of the question whether you want to stop tracing in >> > that very case. Though I agree that the tracer should stop here. >> >> We seem to be agreeing on the functionality. The disagreement seems to >> be in the macro name/functionality mapping. However, the name of the >> function itself is *_bug. I don't see how things are clearer or more >> useful by inserting a *_WARN level macro in a *_bug named function. > > Care to read what I wrote ? Again: I misunderstood what you wrote. I thought you were agreeing that the tracing should stop by default in __schedule_bug. I now realize you meant that you agree it should be possible to stop it, but it should not be the default behavior. Sorry for the confusion. I will change the event to be a *_WARN type. -- Chase