Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401Ab3FZGsa (ORCPT ); Wed, 26 Jun 2013 02:48:30 -0400 Received: from mail-ob0-f171.google.com ([209.85.214.171]:49418 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751195Ab3FZGs2 (ORCPT ); Wed, 26 Jun 2013 02:48:28 -0400 MIME-Version: 1.0 In-Reply-To: <20130625161935.GA10208@jshin-Toonie> References: <51C87ADC.4070409@canonical.com> <20130625161935.GA10208@jshin-Toonie> Date: Wed, 26 Jun 2013 12:18:27 +0530 Message-ID: Subject: Re: od_set_powersave_bias: NULL pointer dereference From: Viresh Kumar To: Jacob Shin Cc: Tim Gardner , "Rafael J. Wysocki" , LKML , cpufreq@vger.kernel.org, linux-pm@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3488 Lines: 97 On 25 June 2013 21:49, Jacob Shin wrote: > Yes, so sorry about that, it looks like I failed to test with: No problem, it happens :) > CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y > CONFIG_CPU_FREQ_GOV_PERFORMANCE=y > CONFIG_CPU_FREQ_GOV_ONDEMAND=y > CONFIG_X86_AMD_FREQ_SENSITIVITY=m > > The following patch fixes this, Tim, could you please test ? : > > ---8<--- > > From 3c727b1f775448599e67c5fb2121d79448e80c90 Mon Sep 17 00:00:00 2001 > From: Jacob Shin > Date: Tue, 25 Jun 2013 10:40:54 -0500 > Subject: [PATCH 1/1] cpufreq: fix NULL pointer deference at > od_set_powersave_bias() > > When initializing the default powersave_bias value, we need to first > make sure that this policy is running the ondemand governor. > > Reported-by: Tim Gardner > Signed-off-by: Jacob Shin > --- > drivers/cpufreq/cpufreq_ondemand.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c > index 4b9bb5d..93eb5cb 100644 > --- a/drivers/cpufreq/cpufreq_ondemand.c > +++ b/drivers/cpufreq/cpufreq_ondemand.c > @@ -47,6 +47,8 @@ static struct od_ops od_ops; > static struct cpufreq_governor cpufreq_gov_ondemand; > #endif > > +static unsigned int default_powersave_bias; > + > static void ondemand_powersave_bias_init_cpu(int cpu) > { > struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu); > @@ -543,7 +545,7 @@ static int od_init(struct dbs_data *dbs_data) > > tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; > tuners->ignore_nice = 0; > - tuners->powersave_bias = 0; > + tuners->powersave_bias = default_powersave_bias; > tuners->io_is_busy = should_io_be_busy(); > > dbs_data->tuners = tuners; > @@ -585,6 +587,7 @@ static void od_set_powersave_bias(unsigned int powersave_bias) > unsigned int cpu; > cpumask_t done; > > + default_powersave_bias = powersave_bias; Why are the above three changes required? And in case they are, then they must have been commited separately. > cpumask_clear(&done); > > get_online_cpus(); > @@ -593,11 +596,17 @@ static void od_set_powersave_bias(unsigned int powersave_bias) > continue; > > policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy; > - dbs_data = policy->governor_data; > - od_tuners = dbs_data->tuners; > - od_tuners->powersave_bias = powersave_bias; > + if (!policy) > + continue; I am not sure if this is enough. What if we had ondemand as the governor initially, then we changed it to something else. Now also cur_policy contains a address and isn't zero. > cpumask_or(&done, &done, policy->cpus); > + > + if (policy->governor != &cpufreq_gov_ondemand) > + continue; > + > + dbs_data = policy->governor_data; > + od_tuners = dbs_data->tuners; > + od_tuners->powersave_bias = default_powersave_bias; > } > put_online_cpus(); > } > -- > 1.7.9.5 > > -- 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/