From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757793Ab0E0DOo (ORCPT ); Wed, 26 May 2010 23:14:44 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:34615 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753601Ab0E0DOn (ORCPT ); Wed, 26 May 2010 23:14:43 -0400 Date: Wed, 26 May 2010 20:14:37 -0700 From: Andrew Morton To: Len Brown Cc: x86@kernel.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Len Brown Subject: Re: [PATCH 2/8] cpuidle: add cpuidle_unregister_driver() error check Message-Id: <20100526201437.51f5c7f7.akpm@linux-foundation.org> In-Reply-To: <56b9c89c17c1a85886f6d1928349e35bbb48c856.1274926772.git.len.brown@intel.com> References: <1274928151-30919-1-git-send-email-lenb@kernel.org> <56b9c89c17c1a85886f6d1928349e35bbb48c856.1274926772.git.len.brown@intel.com> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; 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 Wed, 26 May 2010 22:42:25 -0400 Len Brown wrote: > From: Len Brown > > When cpuidle_unregister_driver() is called with a driver > other than the one that was successfully registered, do nothing. > > Previously we'd NULL-out the one that was registered. > But that required the callers to remember what this > routine already remembers. With this check, the callers > can be simplified. > > Signed-off-by: Len Brown > --- > drivers/cpuidle/driver.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c > index 2257004..30bcd44 100644 > --- a/drivers/cpuidle/driver.c > +++ b/drivers/cpuidle/driver.c > @@ -49,7 +49,8 @@ void cpuidle_unregister_driver(struct cpuidle_driver *drv) > return; > > spin_lock(&cpuidle_driver_lock); > - cpuidle_curr_driver = NULL; > + if (drv == cpuidle_curr_driver) > + cpuidle_curr_driver = NULL; > spin_unlock(&cpuidle_driver_lock); > } This can only happen as a result of a coding bug, yes? If so, the kernel should go BUG() rather than secretly concealing the problem. Also (alternatively), the `drv' arg to this function is superfluous?