Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Ulf Hansson]

On 12 February 2018 at 11:38, Lucas Stach  wrote:
> Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson:
>> On 26 January 2018 at 09:38, Jia-Ju Bai 
>> wrote:
>> > After checking all possible call chains to genpd_dev_pm_detach()
>> > and
>> > genpd_dev_pm_attach() here,
>> > my tool finds that these functions are never called in atomic
>> > context,
>> > namely never in an interrupt handler or holding a spinlock.
>> > Thus mdelay can be replaced with msleep to avoid busy wait.
>> >
>> > This is found by a static analysis tool named DCNS written by
>> > myself.
>> >
>> > Signed-off-by: Jia-Ju Bai 
>> > ---
>> >  drivers/base/power/domain.c |4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/base/power/domain.c
>> > b/drivers/base/power/domain.c
>> > index 0c80bea..f84ac72 100644
>> > --- a/drivers/base/power/domain.c
>> > +++ b/drivers/base/power/domain.c
>> > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device
>> > *dev, bool power_off)
>> > if (ret != -EAGAIN)
>> > break;
>> >
>> > -   mdelay(i);
>> > +   msleep(i);
>>
>> This looks like a nice improvement, however moving to msleep() makes
>> the call to cond_resched() below a bit superfluous. Perhaps remove
>> that as well.
>
> At least for small values of i, msleep also has a high chance to
> overshoot the desired sleep by a lot. It would be better to convert
> them to usleep_range with an acceptable slack.

Ack!

[...]

Kind regards
Uffe

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Ulf Hansson]

On 12 February 2018 at 11:38, Lucas Stach  wrote:
> Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson:
>> On 26 January 2018 at 09:38, Jia-Ju Bai 
>> wrote:
>> > After checking all possible call chains to genpd_dev_pm_detach()
>> > and
>> > genpd_dev_pm_attach() here,
>> > my tool finds that these functions are never called in atomic
>> > context,
>> > namely never in an interrupt handler or holding a spinlock.
>> > Thus mdelay can be replaced with msleep to avoid busy wait.
>> >
>> > This is found by a static analysis tool named DCNS written by
>> > myself.
>> >
>> > Signed-off-by: Jia-Ju Bai 
>> > ---
>> >  drivers/base/power/domain.c |4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/base/power/domain.c
>> > b/drivers/base/power/domain.c
>> > index 0c80bea..f84ac72 100644
>> > --- a/drivers/base/power/domain.c
>> > +++ b/drivers/base/power/domain.c
>> > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device
>> > *dev, bool power_off)
>> > if (ret != -EAGAIN)
>> > break;
>> >
>> > -   mdelay(i);
>> > +   msleep(i);
>>
>> This looks like a nice improvement, however moving to msleep() makes
>> the call to cond_resched() below a bit superfluous. Perhaps remove
>> that as well.
>
> At least for small values of i, msleep also has a high chance to
> overshoot the desired sleep by a lot. It would be better to convert
> them to usleep_range with an acceptable slack.

Ack!

[...]

Kind regards
Uffe

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Lucas Stach]

Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson:
> On 26 January 2018 at 09:38, Jia-Ju Bai 
> wrote:
> > After checking all possible call chains to genpd_dev_pm_detach()
> > and
> > genpd_dev_pm_attach() here,
> > my tool finds that these functions are never called in atomic
> > context,
> > namely never in an interrupt handler or holding a spinlock.
> > Thus mdelay can be replaced with msleep to avoid busy wait.
> > 
> > This is found by a static analysis tool named DCNS written by
> > myself.
> > 
> > Signed-off-by: Jia-Ju Bai 
> > ---
> >  drivers/base/power/domain.c |4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/base/power/domain.c
> > b/drivers/base/power/domain.c
> > index 0c80bea..f84ac72 100644
> > --- a/drivers/base/power/domain.c
> > +++ b/drivers/base/power/domain.c
> > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device
> > *dev, bool power_off)
> > if (ret != -EAGAIN)
> > break;
> > 
> > -   mdelay(i);
> > +   msleep(i);
> 
> This looks like a nice improvement, however moving to msleep() makes
> the call to cond_resched() below a bit superfluous. Perhaps remove
> that as well.

At least for small values of i, msleep also has a high chance to
overshoot the desired sleep by a lot. It would be better to convert
them to usleep_range with an acceptable slack.

Regards,
Lucas

> > cond_resched();
> > }
> > 
> > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
> > if (ret != -EAGAIN)
> > break;
> > 
> > -   mdelay(i);
> > +   msleep(i);
> 
> Ditto.
> 
> > cond_resched();
> > }
> > mutex_unlock(_list_lock);
> > --
> > 1.7.9.5
> > 
> 
> Kind regards
> Uffe

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Lucas Stach]

Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson:
> On 26 January 2018 at 09:38, Jia-Ju Bai 
> wrote:
> > After checking all possible call chains to genpd_dev_pm_detach()
> > and
> > genpd_dev_pm_attach() here,
> > my tool finds that these functions are never called in atomic
> > context,
> > namely never in an interrupt handler or holding a spinlock.
> > Thus mdelay can be replaced with msleep to avoid busy wait.
> > 
> > This is found by a static analysis tool named DCNS written by
> > myself.
> > 
> > Signed-off-by: Jia-Ju Bai 
> > ---
> >  drivers/base/power/domain.c |4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/base/power/domain.c
> > b/drivers/base/power/domain.c
> > index 0c80bea..f84ac72 100644
> > --- a/drivers/base/power/domain.c
> > +++ b/drivers/base/power/domain.c
> > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device
> > *dev, bool power_off)
> > if (ret != -EAGAIN)
> > break;
> > 
> > -   mdelay(i);
> > +   msleep(i);
> 
> This looks like a nice improvement, however moving to msleep() makes
> the call to cond_resched() below a bit superfluous. Perhaps remove
> that as well.

At least for small values of i, msleep also has a high chance to
overshoot the desired sleep by a lot. It would be better to convert
them to usleep_range with an acceptable slack.

Regards,
Lucas

> > cond_resched();
> > }
> > 
> > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
> > if (ret != -EAGAIN)
> > break;
> > 
> > -   mdelay(i);
> > +   msleep(i);
> 
> Ditto.
> 
> > cond_resched();
> > }
> > mutex_unlock(_list_lock);
> > --
> > 1.7.9.5
> > 
> 
> Kind regards
> Uffe

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Ulf Hansson]

On 26 January 2018 at 09:38, Jia-Ju Bai  wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
>
> This is found by a static analysis tool named DCNS written by myself.
>
> Signed-off-by: Jia-Ju Bai 
> ---
>  drivers/base/power/domain.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, 
> bool power_off)
> if (ret != -EAGAIN)
> break;
>
> -   mdelay(i);
> +   msleep(i);

This looks like a nice improvement, however moving to msleep() makes
the call to cond_resched() below a bit superfluous. Perhaps remove
that as well.

> cond_resched();
> }
>
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
> if (ret != -EAGAIN)
> break;
>
> -   mdelay(i);
> +   msleep(i);

Ditto.

> cond_resched();
> }
> mutex_unlock(_list_lock);
> --
> 1.7.9.5
>

Kind regards
Uffe

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Ulf Hansson]

On 26 January 2018 at 09:38, Jia-Ju Bai  wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
>
> This is found by a static analysis tool named DCNS written by myself.
>
> Signed-off-by: Jia-Ju Bai 
> ---
>  drivers/base/power/domain.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, 
> bool power_off)
> if (ret != -EAGAIN)
> break;
>
> -   mdelay(i);
> +   msleep(i);

This looks like a nice improvement, however moving to msleep() makes
the call to cond_resched() below a bit superfluous. Perhaps remove
that as well.

> cond_resched();
> }
>
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
> if (ret != -EAGAIN)
> break;
>
> -   mdelay(i);
> +   msleep(i);

Ditto.

> cond_resched();
> }
> mutex_unlock(_list_lock);
> --
> 1.7.9.5
>

Kind regards
Uffe

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Rafael J. Wysocki]

On Friday, January 26, 2018 9:38:19 AM CET Jia-Ju Bai wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai 
> ---
>  drivers/base/power/domain.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, 
> bool power_off)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>  
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>   mutex_unlock(_list_lock);
> 

Ulf, Kevin, any concerns or objections?

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Rafael J. Wysocki]

On Friday, January 26, 2018 9:38:19 AM CET Jia-Ju Bai wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai 
> ---
>  drivers/base/power/domain.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, 
> bool power_off)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>  
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>   mutex_unlock(_list_lock);
> 

Ulf, Kevin, any concerns or objections?

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Jia-Ju Bai]

On 2018/1/26 18:26, Pavel Machek wrote:

On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote:

After checking all possible call chains to genpd_dev_pm_detach() and
genpd_dev_pm_attach() here,
my tool finds that these functions are never called in atomic context,
namely never in an interrupt handler or holding a spinlock.
Thus mdelay can be replaced with msleep to avoid busy wait.

This is found by a static analysis tool named DCNS written by

myself.

Well, cond_resched() just after msleep certainly looks like that.

Did the patch receive any testing?



Thanks for reply :)

I only perform compilation testing but did not run it in real execution.


Thanks,
Jia-Ju Bai

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Jia-Ju Bai]

On 2018/1/26 18:26, Pavel Machek wrote:

On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote:

After checking all possible call chains to genpd_dev_pm_detach() and
genpd_dev_pm_attach() here,
my tool finds that these functions are never called in atomic context,
namely never in an interrupt handler or holding a spinlock.
Thus mdelay can be replaced with msleep to avoid busy wait.

This is found by a static analysis tool named DCNS written by

myself.

Well, cond_resched() just after msleep certainly looks like that.

Did the patch receive any testing?



Thanks for reply :)

I only perform compilation testing but did not run it in real execution.


Thanks,
Jia-Ju Bai

Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Pavel Machek]

On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by
myself.

Well, cond_resched() just after msleep certainly looks like that.

Did the patch receive any testing?

> Signed-off-by: Jia-Ju Bai 
> ---
>  drivers/base/power/domain.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, 
> bool power_off)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>  
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>   mutex_unlock(_list_lock);

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


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Re: [PATCH] base: power: domain: Replace mdelay with msleep

[Pavel Machek]

On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by
myself.

Well, cond_resched() just after msleep certainly looks like that.

Did the patch receive any testing?

> Signed-off-by: Jia-Ju Bai 
> ---
>  drivers/base/power/domain.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, 
> bool power_off)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>  
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
>   if (ret != -EAGAIN)
>   break;
>  
> - mdelay(i);
> + msleep(i);
>   cond_resched();
>   }
>   mutex_unlock(_list_lock);

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


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