Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756028AbZCRBhV (ORCPT ); Tue, 17 Mar 2009 21:37:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755773AbZCRBhH (ORCPT ); Tue, 17 Mar 2009 21:37:07 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:55410 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753831AbZCRBhG (ORCPT ); Tue, 17 Mar 2009 21:37:06 -0400 Date: Tue, 17 Mar 2009 21:37:02 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Tom Zanussi cc: linux-kernel , Ingo Molnar , =?ISO-8859-15?Q?Fr=E9d=E9ric_Weisbecker?= Subject: Re: [RFC][PATCH 3/4] tracing: add per-event filtering In-Reply-To: <1237271031.8033.151.camel@charm-linux> Message-ID: References: <1237271031.8033.151.camel@charm-linux> 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 Content-Length: 1703 Lines: 56 On Tue, 17 Mar 2009, Tom Zanussi wrote: > diff --git a/kernel/trace/trace_events_stage_3.h b/kernel/trace/trace_events_stage_3.h > index 30627d8..d556274 100644 > --- a/kernel/trace/trace_events_stage_3.h > +++ b/kernel/trace/trace_events_stage_3.h > @@ -154,6 +154,7 @@ static struct ftrace_event_call event_##call; \ > \ > static void ftrace_raw_event_##call(proto) \ > { \ > + struct ftrace_event_call *call = &event_##call; \ > struct ring_buffer_event *event; \ > struct ftrace_raw_##call *entry; \ > unsigned long irq_flags; \ > @@ -172,6 +173,9 @@ static void ftrace_raw_event_##call(proto) \ > assign; \ > \ > trace_current_buffer_unlock_commit(event, irq_flags, pc); \ I have a concern hear about races. Once the commit happens, there's nothing protecting us from being preempted. The reader could in fact come in and consume the commit, and a new write may happen, and this discard will corrupt the data in the buffer. Also in overwrite mode, the writer itself can over write this. Would you be able to move the above unlock_commit after this. I'll make the necessary changes in the commit to check for discarded data. Thanks, -- Steve > + \ > + if (call->preds && !filter_match_preds(call, entry)) \ > + rb_event_discard(event); \ > } \ > \ > static int ftrace_raw_reg_event_##call(void) \ > -- > 1.5.6.3 > > > > > > > -- 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/