Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965122AbaFRHko (ORCPT ); Wed, 18 Jun 2014 03:40:44 -0400 Received: from mail-oa0-f49.google.com ([209.85.219.49]:39133 "EHLO mail-oa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965070AbaFRHkl (ORCPT ); Wed, 18 Jun 2014 03:40:41 -0400 MIME-Version: 1.0 In-Reply-To: <1403050362-20809-1-git-send-email-aplattner@nvidia.com> References: <1403050362-20809-1-git-send-email-aplattner@nvidia.com> Date: Wed, 18 Jun 2014 13:10:40 +0530 Message-ID: Subject: Re: [PATCH] cpufreq: unlock when failing cpufreq_update_policy() From: Viresh Kumar To: Aaron Plattner Cc: "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , "Rafael J. Wysocki" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18 June 2014 05:42, Aaron Plattner wrote: > Commit bd0fa9bb455d introduced a failure path to cpufreq_update_policy() if > cpufreq_driver->get(cpu) returns NULL. However, it jumps to the 'no_policy' > label, which exits without unlocking any of the locks the function acquired > earlier. This causes later calls into cpufreq to hang. > > Fix this by creating a new 'unlock' label and jumping to that instead. > > Fixes: bd0fa9bb455d ("cpufreq: Return error if ->get() failed in cpufreq_update_policy()") > Link: https://devtalk.nvidia.com/default/topic/751903/kernel-3-15-and-nv-drivers-337-340-failed-to-initialize-the-nvidia-kernel-module-gtx-550-ti-/ > Cc: Viresh Kumar > Cc: Rafael J. Wysocki > Signed-off-by: Aaron Plattner > --- > I haven't reproduced this problem so I couldn't test it, but the bug and its > solution seem obvious enough. > > drivers/cpufreq/cpufreq.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index aed2b0cb83dc..5b6d04f3b9ea 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -2264,7 +2264,7 @@ int cpufreq_update_policy(unsigned int cpu) > new_policy.cur = cpufreq_driver->get(cpu); > if (WARN_ON(!new_policy.cur)) { > ret = -EIO; > - goto no_policy; > + goto unlock; > } > > if (!policy->cur) { > @@ -2279,6 +2279,7 @@ int cpufreq_update_policy(unsigned int cpu) > > ret = cpufreq_set_policy(policy, &new_policy); > > +unlock: > up_write(&policy->rwsem); > > cpufreq_cpu_put(policy); Hmm, yes we do have a problem here but the code became a bit ugly now.. Can you please consider this diff instead? diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index aed2b0c..6caced5 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2242,10 +2242,8 @@ int cpufreq_update_policy(unsigned int cpu) struct cpufreq_policy new_policy; int ret; - if (!policy) { - ret = -ENODEV; - goto no_policy; - } + if (!policy) + return = -ENODEV; down_write(&policy->rwsem); @@ -2279,10 +2277,10 @@ int cpufreq_update_policy(unsigned int cpu) ret = cpufreq_set_policy(policy, &new_policy); +no_policy: up_write(&policy->rwsem); cpufreq_cpu_put(policy); -no_policy: return ret; } EXPORT_SYMBOL(cpufreq_update_policy); -- 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/