linux-kernel - Re: [PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add

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Date:	Wed, 27 Jul 2011 21:50:37 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Sven Eckelmann <sven@...fation.org>
Cc:	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	linux-pm@...ts.linux-foundation.org
Subject: Re: [PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

On Wednesday, July 27, 2011, Sven Eckelmann wrote:
> atomic_dec_not_zero is defined for each architecture through
> <linux/atomic.h> to provide the functionality of
> atomic_add_unless(x, -1, 0).
> 
> Signed-off-by: Sven Eckelmann <sven@...fation.org>
> Cc: Len Brown <len.brown@...el.com>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Rafael J. Wysocki <rjw@...k.pl>
> Cc: linux-pm@...ts.linux-foundation.org

Acked-by: Rafael J. Wysocki <rjw@...k.pl>

> ---
>  drivers/base/power/runtime.c |    4 ++--
>  include/linux/pm_runtime.h   |    2 +-
>  kernel/power/hibernate.c     |    4 ++--
>  kernel/power/user.c          |    2 +-
>  4 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 8dc247c..bda10d9 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -401,7 +401,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>  
>  		if (dev->parent) {
>  			parent = dev->parent;
> -			atomic_add_unless(&parent->power.child_count, -1, 0);
> +			atomic_dec_not_zero(&parent->power.child_count);
>  		}
>  	}
>  	wake_up_all(&dev->power.wait_queue);
> @@ -841,7 +841,7 @@ int __pm_runtime_set_status(struct device *dev, unsigned int status)
>  	if (status == RPM_SUSPENDED) {
>  		/* It always is possible to set the status to 'suspended'. */
>  		if (parent) {
> -			atomic_add_unless(&parent->power.child_count, -1, 0);
> +			atomic_dec_not_zero(&parent->power.child_count);
>  			notify_parent = !parent->power.ignore_children;
>  		}
>  		goto out_set;
> diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
> index daac05d..3b4931c 100644
> --- a/include/linux/pm_runtime.h
> +++ b/include/linux/pm_runtime.h
> @@ -63,7 +63,7 @@ static inline void pm_runtime_get_noresume(struct device *dev)
>  
>  static inline void pm_runtime_put_noidle(struct device *dev)
>  {
> -	atomic_add_unless(&dev->power.usage_count, -1, 0);
> +	atomic_dec_not_zero(&dev->power.usage_count);
>  }
>  
>  static inline bool device_run_wake(struct device *dev)
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 8f7b1db..0ba8d87 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -606,7 +606,7 @@ int hibernate(void)
>  
>  	mutex_lock(&pm_mutex);
>  	/* The snapshot device should not be opened while we're running */
> -	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
> +	if (!atomic_dec_not_zero(&snapshot_device_available)) {
>  		error = -EBUSY;
>  		goto Unlock;
>  	}
> @@ -756,7 +756,7 @@ static int software_resume(void)
>  		goto Unlock;
>  
>  	/* The snapshot device should not be opened while we're running */
> -	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
> +	if (!atomic_dec_not_zero(&snapshot_device_available)) {
>  		error = -EBUSY;
>  		swsusp_close(FMODE_READ);
>  		goto Unlock;
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index 42ddbc6..1c1cc01 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -72,7 +72,7 @@ static int snapshot_open(struct inode *inode, struct file *filp)
>  
>  	mutex_lock(&pm_mutex);
>  
> -	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
> +	if (!atomic_dec_not_zero(&snapshot_device_available)) {
>  		error = -EBUSY;
>  		goto Unlock;
>  	}
> 

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