[PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

[PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

[Sven Eckelmann]

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@narfation.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: linux-pm@lists.linux-foundation.org
---
 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;
 	}
-- 
1.7.5.4

Re: [PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

[Rafael J. Wysocki]

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@narfation.org>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Rafael J. Wysocki <rjw@sisk.pl>
> Cc: linux-pm@lists.linux-foundation.org

Acked-by: Rafael J. Wysocki <rjw@sisk.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;
>  	}
> 

Re: [PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

[Pavel Machek]

Hi!

> > 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@narfation.org>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: Pavel Machek <pavel@ucw.cz>
> > Cc: Rafael J. Wysocki <rjw@sisk.pl>
> > Cc: linux-pm@lists.linux-foundation.org
> 
> Acked-by: Rafael J. Wysocki <rjw@sisk.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);

I'd like to understand... Why not atomic_dec in the first place? Count
should be exact, anyway, or we run into problems, right?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

[Rafael J. Wysocki]

On Wednesday, July 27, 2011, Pavel Machek wrote:
> Hi!
> 
> > > 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@narfation.org>
> > > Cc: Len Brown <len.brown@intel.com>
> > > Cc: Pavel Machek <pavel@ucw.cz>
> > > Cc: Rafael J. Wysocki <rjw@sisk.pl>
> > > Cc: linux-pm@lists.linux-foundation.org
> > 
> > Acked-by: Rafael J. Wysocki <rjw@sisk.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);
> 
> I'd like to understand... Why not atomic_dec in the first place? Count
> should be exact, anyway, or we run into problems, right?

Well, we'll also run into trouble if the count becomes negative.  We might
throw a WARN_ON() there if the old value weren't as expected, but that
would be a separate patch.

Thanks,
Rafael