From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759804AbZEHE4c (ORCPT ); Fri, 8 May 2009 00:56:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754946AbZEHE4G (ORCPT ); Fri, 8 May 2009 00:56:06 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54103 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757314AbZEHE4F (ORCPT ); Fri, 8 May 2009 00:56:05 -0400 Date: Thu, 7 May 2009 21:54:27 -0700 From: Andrew Morton To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar Subject: Re: [PATCH 4/4] ring-buffer: change WARN_ON from checking preempt_count to preemptible Message-Id: <20090507215427.4256cc3c.akpm@linux-foundation.org> In-Reply-To: <20090508043331.726786617@goodmis.org> References: <20090508043250.372421144@goodmis.org> <20090508043331.726786617@goodmis.org> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 08 May 2009 00:32:54 -0400 Steven Rostedt wrote: > From: Steven Rostedt > > There's a WARN_ON in the ring buffer code that makes sure preemption > is disabled. It checks "!preempt_count()". But when CONFIG_PREEMPT is not > enabled, preempt_count() is always zero, and this will trigger the warning. > > [ Impact: prevent false warning on non preemptible kernels ] > > Signed-off-by: Steven Rostedt > --- > kernel/trace/ring_buffer.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 3ae5ccf..3611706 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -1688,7 +1688,7 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer, > * committed yet. Thus we can assume that preemption > * is still disabled. > */ > - RB_WARN_ON(buffer, !preempt_count()); > + RB_WARN_ON(buffer, preemptible()); > > cpu = smp_processor_id(); > cpu_buffer = buffer->buffers[cpu]; smp_processor_id() will warn too.