[PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Prevent rpm_get_suppliers() from returning an error code if runtime
PM is disabled for one or more of the supplier devices it wants to
runtime-resume, so as to make runtime PM work for devices with links
to suppliers that don't use runtime PM (such links may be created
during device enumeration even before it is known whether or not
runtime PM will be enabled for the devices in question, for example).

Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: 21d5c57b3726 (PM / runtime: Use device links)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/base/power/runtime.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -276,7 +276,8 @@ static int rpm_get_suppliers(struct devi
 			continue;
 
 		retval = pm_runtime_get_sync(link->supplier);
-		if (retval < 0) {
+		/* Ignore suppliers with disabled runtime PM. */
+		if (retval < 0 && retval != -EACCES) {
 			pm_runtime_put_noidle(link->supplier);
 			return retval;
 		}

Re: [PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[Lukas Wunner]

On Fri, Dec 01, 2017 at 02:58:34PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Prevent rpm_get_suppliers() from returning an error code if runtime
> PM is disabled for one or more of the supplier devices it wants to
> runtime-resume, so as to make runtime PM work for devices with links
> to suppliers that don't use runtime PM (such links may be created
> during device enumeration even before it is known whether or not
> runtime PM will be enabled for the devices in question, for example).
> 
> Reported-by: Adrian Hunter <adrian.hunter@intel.com>
> Fixes: 21d5c57b3726 (PM / runtime: Use device links)
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/base/power/runtime.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -276,7 +276,8 @@ static int rpm_get_suppliers(struct devi
>  			continue;
>  
>  		retval = pm_runtime_get_sync(link->supplier);
> -		if (retval < 0) {
> +		/* Ignore suppliers with disabled runtime PM. */
> +		if (retval < 0 && retval != -EACCES) {
>  			pm_runtime_put_noidle(link->supplier);
>  			return retval;
>  		}
> 

You could alternatively call pm_runtime_get_sync() under the condition
link->supplier->power.disable_depth > 0 but then the usage_count wouldn't
be incremented and I guess we want that in case runtime PM is only
temporarily disabled and later enabled, right?

I'm wondering if checking for that condition in lieu of retval != -EACCES
would be more explicit and less fragile here (there's a theoretical
possibility that the supplier's ->runtime_resume callback returns -EACCESS,
leading to a false positive).

Apart from that,

Reviewed-by: Lukas Wunner <lukas@wunner.de>

Thanks,

Lukas

Re: [PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[Rafael J. Wysocki]

On Friday, December 1, 2017 3:18:01 PM CET Lukas Wunner wrote:
> On Fri, Dec 01, 2017 at 02:58:34PM +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > 
> > Prevent rpm_get_suppliers() from returning an error code if runtime
> > PM is disabled for one or more of the supplier devices it wants to
> > runtime-resume, so as to make runtime PM work for devices with links
> > to suppliers that don't use runtime PM (such links may be created
> > during device enumeration even before it is known whether or not
> > runtime PM will be enabled for the devices in question, for example).
> > 
> > Reported-by: Adrian Hunter <adrian.hunter@intel.com>
> > Fixes: 21d5c57b3726 (PM / runtime: Use device links)
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >  drivers/base/power/runtime.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > Index: linux-pm/drivers/base/power/runtime.c
> > ===================================================================
> > --- linux-pm.orig/drivers/base/power/runtime.c
> > +++ linux-pm/drivers/base/power/runtime.c
> > @@ -276,7 +276,8 @@ static int rpm_get_suppliers(struct devi
> >  			continue;
> >  
> >  		retval = pm_runtime_get_sync(link->supplier);
> > -		if (retval < 0) {
> > +		/* Ignore suppliers with disabled runtime PM. */
> > +		if (retval < 0 && retval != -EACCES) {
> >  			pm_runtime_put_noidle(link->supplier);
> >  			return retval;
> >  		}
> > 
> 
> You could alternatively call pm_runtime_get_sync() under the condition
> link->supplier->power.disable_depth > 0 but then the usage_count wouldn't
> be incremented and I guess we want that in case runtime PM is only
> temporarily disabled and later enabled, right?
> 
> I'm wondering if checking for that condition in lieu of retval != -EACCES
> would be more explicit and less fragile here (there's a theoretical
> possibility that the supplier's ->runtime_resume callback returns -EACCESS,
> leading to a false positive).

That will be filtered out by rpm_callback() which converts -EACCES to -EIO.

> 
> Apart from that,
> 
> Reviewed-by: Lukas Wunner <lukas@wunner.de>

Thanks,
Rafael

Re: [PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[Rafael J. Wysocki]

On Fri, Dec 1, 2017 at 3:18 PM, Lukas Wunner <lukas@wunner.de> wrote:
> On Fri, Dec 01, 2017 at 02:58:34PM +0100, Rafael J. Wysocki wrote:
>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>>
>> Prevent rpm_get_suppliers() from returning an error code if runtime
>> PM is disabled for one or more of the supplier devices it wants to
>> runtime-resume, so as to make runtime PM work for devices with links
>> to suppliers that don't use runtime PM (such links may be created
>> during device enumeration even before it is known whether or not
>> runtime PM will be enabled for the devices in question, for example).
>>
>> Reported-by: Adrian Hunter <adrian.hunter@intel.com>
>> Fixes: 21d5c57b3726 (PM / runtime: Use device links)
>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> ---
>>  drivers/base/power/runtime.c |    3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> Index: linux-pm/drivers/base/power/runtime.c
>> ===================================================================
>> --- linux-pm.orig/drivers/base/power/runtime.c
>> +++ linux-pm/drivers/base/power/runtime.c
>> @@ -276,7 +276,8 @@ static int rpm_get_suppliers(struct devi
>>                       continue;
>>
>>               retval = pm_runtime_get_sync(link->supplier);
>> -             if (retval < 0) {
>> +             /* Ignore suppliers with disabled runtime PM. */
>> +             if (retval < 0 && retval != -EACCES) {
>>                       pm_runtime_put_noidle(link->supplier);
>>                       return retval;
>>               }
>>
>
> You could alternatively call pm_runtime_get_sync() under the condition
> link->supplier->power.disable_depth > 0 but then the usage_count wouldn't
> be incremented and I guess we want that in case runtime PM is only
> temporarily disabled and later enabled, right?

Right.

Thanks,
Rafael

Re: [PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[Adrian Hunter]

On 01/12/17 15:58, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Prevent rpm_get_suppliers() from returning an error code if runtime
> PM is disabled for one or more of the supplier devices it wants to
> runtime-resume, so as to make runtime PM work for devices with links
> to suppliers that don't use runtime PM (such links may be created
> during device enumeration even before it is known whether or not
> runtime PM will be enabled for the devices in question, for example).
> 
> Reported-by: Adrian Hunter <adrian.hunter@intel.com>
> Fixes: 21d5c57b3726 (PM / runtime: Use device links)
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Tested-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  drivers/base/power/runtime.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -276,7 +276,8 @@ static int rpm_get_suppliers(struct devi
>  			continue;
>  
>  		retval = pm_runtime_get_sync(link->supplier);
> -		if (retval < 0) {
> +		/* Ignore suppliers with disabled runtime PM. */
> +		if (retval < 0 && retval != -EACCES) {
>  			pm_runtime_put_noidle(link->supplier);
>  			return retval;
>  		}
> 
> 

Re: [PATCH] PM / runtime: Fix handling of suppliers with disabled runtime PM

[Ulf Hansson]

On 1 December 2017 at 14:58, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Prevent rpm_get_suppliers() from returning an error code if runtime
> PM is disabled for one or more of the supplier devices it wants to
> runtime-resume, so as to make runtime PM work for devices with links
> to suppliers that don't use runtime PM (such links may be created
> during device enumeration even before it is known whether or not
> runtime PM will be enabled for the devices in question, for example).
>
> Reported-by: Adrian Hunter <adrian.hunter@intel.com>
> Fixes: 21d5c57b3726 (PM / runtime: Use device links)
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
>  drivers/base/power/runtime.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -276,7 +276,8 @@ static int rpm_get_suppliers(struct devi
>                         continue;
>
>                 retval = pm_runtime_get_sync(link->supplier);
> -               if (retval < 0) {
> +               /* Ignore suppliers with disabled runtime PM. */
> +               if (retval < 0 && retval != -EACCES) {
>                         pm_runtime_put_noidle(link->supplier);
>                         return retval;
>                 }
>