Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757948Ab3DBWuR (ORCPT ); Tue, 2 Apr 2013 18:50:17 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:50397 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755073Ab3DBWuO (ORCPT ); Tue, 2 Apr 2013 18:50:14 -0400 From: "Rafael J. Wysocki" To: Viresh Kumar Cc: Nathan Zimmer , cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 1/2] cpufreq: split the cpufreq_driver_lock and use the rcu Date: Wed, 03 Apr 2013 00:57:50 +0200 Message-ID: <8456428.Vj8uefv4LI@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.9.0-rc4+; KDE/4.9.5; x86_64; ; ) In-Reply-To: References: <5159C147.70800@sgi.com> <20130402145536.GA31757@gulag1.americas.sgi.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 834 Lines: 23 On Tuesday, April 02, 2013 08:29:12 PM Viresh Kumar wrote: > On 2 April 2013 20:25, Nathan Zimmer wrote: > > The lock is unneeded if we expect register and unregister driver to not be > > called from muliple threads at once. I didn't make that assumption. > > Hmm.. But doesn't rcu part take care of that too?? Two writers > updating stuff simultaneously? RCU doesn't cover that in general. Additional locking is needed to provide synchronization between writers. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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/