Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759284AbYLDPpF (ORCPT ); Thu, 4 Dec 2008 10:45:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755597AbYLDPov (ORCPT ); Thu, 4 Dec 2008 10:44:51 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:43820 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758717AbYLDPor (ORCPT ); Thu, 4 Dec 2008 10:44:47 -0500 Date: Thu, 4 Dec 2008 10:44:44 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Dave Hansen cc: "Eric W. Biederman" , Frederic Weisbecker , linux-kernel@vger.kernel.org, Steven Rostedt , containers@lists.osdl.org, Ingo Molnar , Sukadev Bhattiprolu , Andrew Morton , Dipankar Sarma Subject: Re: [PATCH 2/3] ftrace: use struct pid In-Reply-To: <1228405291.13111.86.camel@nimitz> Message-ID: References: <20081204052638.425740534@goodmis.org> <20081204052735.175697908@goodmis.org> <1228395378.13111.23.camel@nimitz> <1228396022.13111.27.camel@nimitz> <1228405291.13111.86.camel@nimitz> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) 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: 683 Lines: 20 On Thu, 4 Dec 2008, Dave Hansen wrote: > > > > We probably should. Historically read_lock(&tasklist_lock) implies > > rcu_read_lock(). And the tasklist lock is what we hold when it is > > safe. > > So, Dipankar tells me that you really do need rcu_read_lock/unlock() for > the guarantee here; the tasklist lock is not sufficient. The realtime > kernel will preempt even those sections covered by spinlocks. Yes it will. -- Steve -- 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/