linux-kernel - Re: [RFC PATCH 12/19] cpufreq: fix locking of policy->rwsem in cpufreq_init

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Message-ID: <20160112103956.GD1084@ubuntu>
Date:	Tue, 12 Jan 2016 16:09:56 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Juri Lelli <juri.lelli@....com>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	peterz@...radead.org, rjw@...ysocki.net, mturquette@...libre.com,
	steve.muckle@...aro.org, vincent.guittot@...aro.org,
	morten.rasmussen@....com, dietmar.eggemann@....com
Subject: Re: [RFC PATCH 12/19] cpufreq: fix locking of policy->rwsem in
 cpufreq_init_policy

On 11-01-16, 17:35, Juri Lelli wrote:
> There are paths in cpufreq_init_policy where policy is used, but its rwsem
> is not held.
> 
> Fix it.
> 
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Juri Lelli <juri.lelli@....com>
> ---
>  drivers/cpufreq/cpufreq.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index e7fc5c9..2c7cc6c73 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -998,21 +998,24 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
>  {
>  	int ret = 0;
>  
> +	down_write(&policy->rwsem);
> +
>  	/* Has this CPU been taken care of already? */
> -	if (cpumask_test_cpu(cpu, policy->cpus))
> +	if (cpumask_test_cpu(cpu, policy->cpus)) {
> +		up_write(&policy->rwsem);

Perhaps create a label at the end to unlock the rwsem and jump to it?

-- 
viresh