linux-kernel - Re: [PATCH] cpufreq: Avoid double kobject_put() for the same kobject in error code path

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Date:	Fri, 02 Aug 2013 12:24:01 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Linux PM list <linux-pm@...r.kernel.org>, cpufreq@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [PATCH] cpufreq: Avoid double kobject_put() for the same kobject
 in error code path

On 08/02/2013 03:01 AM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> The only case triggering a jump to the err_out_unregister label in
> __cpufreq_add_dev() is when cpufreq_add_dev_interface() fails.
> However, if cpufreq_add_dev_interface() fails, it calls kobject_put()
> for the policy kobject in its error code path and since that causes
> the kobject's refcount to become 0, the additional kobject_put() for
> the same kobject under err_out_unregister and the
> wait_for_completion() following it are pointless, so drop them.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>

Regards,
Srivatsa S. Bhat

> ---
>  drivers/cpufreq/cpufreq.c |    3 ---
>  1 file changed, 3 deletions(-)
> 
> Index: linux-pm/drivers/cpufreq/cpufreq.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> +++ linux-pm/drivers/cpufreq/cpufreq.c
> @@ -1109,9 +1109,6 @@ err_out_unregister:
>  	}
>  	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> 
> -	kobject_put(&policy->kobj);
> -	wait_for_completion(&policy->kobj_unregister);
> -
>  err_set_policy_cpu:
>  	per_cpu(cpufreq_policy_cpu, cpu) = -1;
>  	cpufreq_policy_free(policy);
> 

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