From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756359AbZHGCDh (ORCPT ); Thu, 6 Aug 2009 22:03:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756324AbZHGCDg (ORCPT ); Thu, 6 Aug 2009 22:03:36 -0400 Received: from ey-out-2122.google.com ([74.125.78.24]:1104 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756317AbZHGCDf (ORCPT ); Thu, 6 Aug 2009 22:03:35 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=tq0y2Bn8AcD4XI91F+8xonIzEI/VMWm+I3aYhjQ+qlrUY6eWy3UJgiE6D2ZmyC5sqz Px+qUqsdjli4zhl2iigEQuklk6Pipp5w0yUfb3WaFWi5bZnlu4dRBZo25Rb6C6g2GlCS 8Y0J0RosvvIcCE4izCjUtApghfJIA4EdYjp8g= Date: Fri, 7 Aug 2009 04:03:32 +0200 From: Frederic Weisbecker To: Jonathan Corbet Cc: LKML , Ingo Molnar , Mark Gross Subject: Re: [PATCH 1/2] pm_qos: remove BKL Message-ID: <20090807020330.GA5425@nowhere> References: <20090806135841.46682114@bike.lwn.net> <20090806135953.7706e57d@bike.lwn.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090806135953.7706e57d@bike.lwn.net> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 06, 2009 at 01:59:53PM -0600, Jonathan Corbet wrote: > pm_qos_power_open got its lock_kernel() calls from the open() pushdown. A > look at the code shows that the only global resources accessed are > pm_qos_array and "name". pm_qos_array doesn't change (things pointed to > therein do change, but they are atomics and/or are protected by > pm_qos_lock). Accesses to "name" are totally unprotected with or without > the BKL; that will be fixed shortly. The BKL is not helpful here; take it > out. > > Signed-off-by: Jonathan Corbet Is there a 2/2 missing patch in the series, or may be I missed it. I guess it fixes the racy "name"... > --- > kernel/pm_qos_params.c | 8 +------- > 1 files changed, 1 insertions(+), 7 deletions(-) > > diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c > index dfdec52..d96b83e 100644 > --- a/kernel/pm_qos_params.c > +++ b/kernel/pm_qos_params.c > @@ -29,7 +29,6 @@ > > #include > #include > -#include > #include > #include > #include > @@ -352,20 +351,15 @@ static int pm_qos_power_open(struct inode *inode, struct file *filp) > int ret; > long pm_qos_class; > > - lock_kernel(); > pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); > if (pm_qos_class >= 0) { > filp->private_data = (void *)pm_qos_class; > sprintf(name, "process_%d", current->pid); > ret = pm_qos_add_requirement(pm_qos_class, name, > PM_QOS_DEFAULT_VALUE); > - if (ret >= 0) { > - unlock_kernel(); > + if (ret >= 0) > return 0; > - } > } > - unlock_kernel(); > - > return -EPERM; > } > > -- > 1.6.2.5 > > -- > 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/