Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754946Ab2F0Af5 (ORCPT ); Tue, 26 Jun 2012 20:35:57 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:53109 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754481Ab2F0Af4 convert rfc822-to-8bit (ORCPT ); Tue, 26 Jun 2012 20:35:56 -0400 MIME-Version: 1.0 In-Reply-To: References: <1340060577-9112-1-git-send-email-dhsharp@google.com> <1340293617.27036.177.camel@gandalf.stny.rr.com> <1340407900.27036.275.camel@gandalf.stny.rr.com> From: David Sharp Date: Tue, 26 Jun 2012 17:35:34 -0700 Message-ID: Subject: Re: [PATCH] ring-buffer: fix uninitialized read_stamp To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, vnagarnaik@google.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1601 Lines: 37 On Fri, Jun 22, 2012 at 6:27 PM, David Sharp wrote: > On Fri, Jun 22, 2012 at 4:31 PM, Steven Rostedt wrote: >> >> Now I think you may understand my patch. > > Yeah, mostly. At least enough that I think it's worth testing. But Monday. I got around to testing your patch today, and it fixes the issue. No bad-looking timestamps in 40 runs, whereas could reproduce within 3 runs before. Do you want me to send you a fresh patch, or just use the one you have? >>> On Thu, Jun 21, 2012 at 8:56 AM, Steven Rostedt wrote: >>> > Does something like this work for you. Note, this is totally untested! >>> > >>> > -- Steve >>> > >>> > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c >>> > index ad0239b..5943044 100644 >>> > --- a/kernel/trace/ring_buffer.c >>> > +++ b/kernel/trace/ring_buffer.c >>> > @@ -3246,6 +3246,10 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) >>> >        if (cpu_buffer->commit_page == cpu_buffer->reader_page) >>> >                goto out; >>> > >>> > +       /* Don't bother swapping if the ring buffer is empty */ >>> > +       if (rb_num_of_entries(cpu_buffer) == 0) >>> > +               goto out; >>> > + >>> >        /* >>> >         * Reset the reader page to size zero. >>> >         */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/