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Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation

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  Re: [PATCH v2] PM / sleep: prohibit devices probing during  suspend/hibernation Pavel Machek <pavel@ucw.cz> - 2015-11-05 23:20 +0100
    Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-11-06 00:50 +0100
      Re: [PATCH v2] PM / sleep: prohibit devices probing during  suspend/hibernation Grygorii Strashko <grygorii.strashko@ti.com> - 2015-11-06 11:00 +0100
        Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-11-06 23:20 +0100

#1263581 — Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation

On Mon 2015-10-19 23:54:24, Grygorii Strashko wrote:
> It is unsafe [1] if probing of devices will happen during suspend or
> hibernation and system behavior will be unpredictable in this case
> (for example: after successful probe the device potentially has a different
>  set of PM callbacks than before [2]).
> So, let's prohibit device's probing in dpm_prepare() and defer their
> probes instead. The normal behavior will be restored in dpm_complete().
> 
> This patch introduces new DD core APIs:
>  device_defer_all_probes_enable()
>    It will disable probing of devices and defer their probes.
>  device_defer_all_probes_disable()
>    It will restore normal behavior and trigger re-probing of deferred
>    devices.
> 
> [1] https://lkml.org/lkml/2015/9/11/554
> [2] https://lkml.org/lkml/2015/9/15/1039
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> ---
> Changes in v2:
> - DD core API device_defer_all_probes(bool enable) split on two
>   void device_defer_all_probes_enable(void);
>   void device_defer_all_probes_disable(void);
> - more comments added
> 
> Link on v1:
> - https://lkml.org/lkml/2015/10/8/681
> 
>  drivers/base/base.h       |  2 ++
>  drivers/base/dd.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
>  drivers/base/power/main.c | 17 +++++++++++++++++
>  3 files changed, 66 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index 1782f3a..c332b68 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -131,6 +131,8 @@ extern void device_remove_groups(struct device *dev,
>  extern char *make_class_name(const char *name, struct kobject *kobj);
>  
>  extern int devres_release_all(struct device *dev);
> +extern void device_defer_all_probes_enable(void);
> +extern void device_defer_all_probes_disable(void);
>  
>  /* /sys/devices directory */
>  extern struct kset *devices_kset;
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index be0eb46..b8d9e70 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -55,6 +55,13 @@ static struct workqueue_struct *deferred_wq;
>  static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
>  
>  /*
> + * In some cases, like suspend to RAM or hibernation, It might be reasonable
> + * to prohibit probing of devices as it could be unsafe.
> + * Once defer_all_probes is true all drivers probes will be forcibly deferred.
> + */
> +static bool defer_all_probes;
> +
> +/*
>   * deferred_probe_work_func() - Retry probing devices in the active list.
>   */
>  static void deferred_probe_work_func(struct work_struct *work)
> @@ -172,6 +179,30 @@ static void driver_deferred_probe_trigger(void)
>  }
>  
>  /**
> + * device_defer_all_probes_enable() - Enable deferring of device's probes
> + *
> + *	It will disable probing of devices and defer their probes.
> + */
> +void device_defer_all_probes_enable(void)
> +{
> +	defer_all_probes = true;
> +	/* sync with probes to avoid races. */
> +	wait_for_device_probe();
> +}

device_pause_probing()?

> +/**
> + * device_defer_all_probes_disable() - Disable deferring of device's probes
> + *
> + *	It will restore normal behavior and trigger re-probing of deferred
> + * devices.
> + */

Hmm. This is not quite a double negative... but it sounds like one.

device_restart_probing()?

Thanks,
									Pavel

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#1263636 — Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation

On Thursday, November 05, 2015 11:19:03 PM Pavel Machek wrote:
> On Mon 2015-10-19 23:54:24, Grygorii Strashko wrote:
> > It is unsafe [1] if probing of devices will happen during suspend or
> > hibernation and system behavior will be unpredictable in this case
> > (for example: after successful probe the device potentially has a different
> >  set of PM callbacks than before [2]).
> > So, let's prohibit device's probing in dpm_prepare() and defer their
> > probes instead. The normal behavior will be restored in dpm_complete().
> > 
> > This patch introduces new DD core APIs:
> >  device_defer_all_probes_enable()
> >    It will disable probing of devices and defer their probes.
> >  device_defer_all_probes_disable()
> >    It will restore normal behavior and trigger re-probing of deferred
> >    devices.
> > 
> > [1] https://lkml.org/lkml/2015/9/11/554
> > [2] https://lkml.org/lkml/2015/9/15/1039
> > Cc: Alan Stern <stern@rowland.harvard.edu>
> > Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> > Cc: Thierry Reding <thierry.reding@gmail.com>
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> > ---
> > Changes in v2:
> > - DD core API device_defer_all_probes(bool enable) split on two
> >   void device_defer_all_probes_enable(void);
> >   void device_defer_all_probes_disable(void);
> > - more comments added
> > 
> > Link on v1:
> > - https://lkml.org/lkml/2015/10/8/681
> > 
> >  drivers/base/base.h       |  2 ++
> >  drivers/base/dd.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
> >  drivers/base/power/main.c | 17 +++++++++++++++++
> >  3 files changed, 66 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/base/base.h b/drivers/base/base.h
> > index 1782f3a..c332b68 100644
> > --- a/drivers/base/base.h
> > +++ b/drivers/base/base.h
> > @@ -131,6 +131,8 @@ extern void device_remove_groups(struct device *dev,
> >  extern char *make_class_name(const char *name, struct kobject *kobj);
> >  
> >  extern int devres_release_all(struct device *dev);
> > +extern void device_defer_all_probes_enable(void);
> > +extern void device_defer_all_probes_disable(void);
> >  
> >  /* /sys/devices directory */
> >  extern struct kset *devices_kset;
> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> > index be0eb46..b8d9e70 100644
> > --- a/drivers/base/dd.c
> > +++ b/drivers/base/dd.c
> > @@ -55,6 +55,13 @@ static struct workqueue_struct *deferred_wq;
> >  static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
> >  
> >  /*
> > + * In some cases, like suspend to RAM or hibernation, It might be reasonable
> > + * to prohibit probing of devices as it could be unsafe.
> > + * Once defer_all_probes is true all drivers probes will be forcibly deferred.
> > + */
> > +static bool defer_all_probes;
> > +
> > +/*
> >   * deferred_probe_work_func() - Retry probing devices in the active list.
> >   */
> >  static void deferred_probe_work_func(struct work_struct *work)
> > @@ -172,6 +179,30 @@ static void driver_deferred_probe_trigger(void)
> >  }
> >  
> >  /**
> > + * device_defer_all_probes_enable() - Enable deferring of device's probes
> > + *
> > + *	It will disable probing of devices and defer their probes.
> > + */
> > +void device_defer_all_probes_enable(void)
> > +{
> > +	defer_all_probes = true;
> > +	/* sync with probes to avoid races. */
> > +	wait_for_device_probe();
> > +}
> 
> device_pause_probing()?
> 
> > +/**
> > + * device_defer_all_probes_disable() - Disable deferring of device's probes
> > + *
> > + *	It will restore normal behavior and trigger re-probing of deferred
> > + * devices.
> > + */
> 
> Hmm. This is not quite a double negative... but it sounds like one.
> 
> device_restart_probing()?

I _start/_stop would be fine by me too.

Thanks,
Rafael

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#1263877

On 11/06/2015 02:13 AM, Rafael J. Wysocki wrote:
> On Thursday, November 05, 2015 11:19:03 PM Pavel Machek wrote:
>> On Mon 2015-10-19 23:54:24, Grygorii Strashko wrote:
>>> It is unsafe [1] if probing of devices will happen during suspend or
>>> hibernation and system behavior will be unpredictable in this case
>>> (for example: after successful probe the device potentially has a different
>>>   set of PM callbacks than before [2]).
>>> So, let's prohibit device's probing in dpm_prepare() and defer their
>>> probes instead. The normal behavior will be restored in dpm_complete().
>>>
>>> This patch introduces new DD core APIs:
>>>   device_defer_all_probes_enable()
>>>     It will disable probing of devices and defer their probes.
>>>   device_defer_all_probes_disable()
>>>     It will restore normal behavior and trigger re-probing of deferred
>>>     devices.
>>>
>>> [1] https://lkml.org/lkml/2015/9/11/554
>>> [2] https://lkml.org/lkml/2015/9/15/1039
>>> Cc: Alan Stern <stern@rowland.harvard.edu>
>>> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
>>> Cc: Thierry Reding <thierry.reding@gmail.com>
>>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
>>> ---
>>> Changes in v2:
>>> - DD core API device_defer_all_probes(bool enable) split on two
>>>    void device_defer_all_probes_enable(void);
>>>    void device_defer_all_probes_disable(void);
>>> - more comments added
>>>
>>> Link on v1:
>>> - https://lkml.org/lkml/2015/10/8/681
>>>
>>>   drivers/base/base.h       |  2 ++
>>>   drivers/base/dd.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
>>>   drivers/base/power/main.c | 17 +++++++++++++++++
>>>   3 files changed, 66 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/base/base.h b/drivers/base/base.h
>>> index 1782f3a..c332b68 100644
>>> --- a/drivers/base/base.h
>>> +++ b/drivers/base/base.h
>>> @@ -131,6 +131,8 @@ extern void device_remove_groups(struct device *dev,
>>>   extern char *make_class_name(const char *name, struct kobject *kobj);
>>>
>>>   extern int devres_release_all(struct device *dev);
>>> +extern void device_defer_all_probes_enable(void);
>>> +extern void device_defer_all_probes_disable(void);
>>>
>>>   /* /sys/devices directory */
>>>   extern struct kset *devices_kset;
>>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>>> index be0eb46..b8d9e70 100644
>>> --- a/drivers/base/dd.c
>>> +++ b/drivers/base/dd.c
>>> @@ -55,6 +55,13 @@ static struct workqueue_struct *deferred_wq;
>>>   static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
>>>
>>>   /*
>>> + * In some cases, like suspend to RAM or hibernation, It might be reasonable
>>> + * to prohibit probing of devices as it could be unsafe.
>>> + * Once defer_all_probes is true all drivers probes will be forcibly deferred.
>>> + */
>>> +static bool defer_all_probes;
>>> +
>>> +/*
>>>    * deferred_probe_work_func() - Retry probing devices in the active list.
>>>    */
>>>   static void deferred_probe_work_func(struct work_struct *work)
>>> @@ -172,6 +179,30 @@ static void driver_deferred_probe_trigger(void)
>>>   }
>>>
>>>   /**
>>> + * device_defer_all_probes_enable() - Enable deferring of device's probes
>>> + *
>>> + *	It will disable probing of devices and defer their probes.
>>> + */
>>> +void device_defer_all_probes_enable(void)
>>> +{
>>> +	defer_all_probes = true;
>>> +	/* sync with probes to avoid races. */
>>> +	wait_for_device_probe();
>>> +}
>>
>> device_pause_probing()?

device_stop_probing(). Right?

>>
>>> +/**
>>> + * device_defer_all_probes_disable() - Disable deferring of device's probes
>>> + *
>>> + *	It will restore normal behavior and trigger re-probing of deferred
>>> + * devices.
>>> + */

device_start_probing(). Right?

>>
>> Hmm. This is not quite a double negative... but it sounds like one.
>>
>> device_restart_probing()?
>
> I _start/_stop would be fine by me too.

Ok. So do I need rename/resend it again?
Probably, I'll need to wait for -rc1 before resending.

-- 
regards,
-grygorii
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#1264605 — Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation

On Friday, November 06, 2015 11:58:40 AM Grygorii Strashko wrote:
> On 11/06/2015 02:13 AM, Rafael J. Wysocki wrote:
> > On Thursday, November 05, 2015 11:19:03 PM Pavel Machek wrote:
> >> On Mon 2015-10-19 23:54:24, Grygorii Strashko wrote:
> >>> It is unsafe [1] if probing of devices will happen during suspend or
> >>> hibernation and system behavior will be unpredictable in this case
> >>> (for example: after successful probe the device potentially has a different
> >>>   set of PM callbacks than before [2]).
> >>> So, let's prohibit device's probing in dpm_prepare() and defer their
> >>> probes instead. The normal behavior will be restored in dpm_complete().
> >>>
> >>> This patch introduces new DD core APIs:
> >>>   device_defer_all_probes_enable()
> >>>     It will disable probing of devices and defer their probes.
> >>>   device_defer_all_probes_disable()
> >>>     It will restore normal behavior and trigger re-probing of deferred
> >>>     devices.
> >>>
> >>> [1] https://lkml.org/lkml/2015/9/11/554
> >>> [2] https://lkml.org/lkml/2015/9/15/1039
> >>> Cc: Alan Stern <stern@rowland.harvard.edu>
> >>> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> >>> Cc: Thierry Reding <thierry.reding@gmail.com>
> >>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> >>> ---
> >>> Changes in v2:
> >>> - DD core API device_defer_all_probes(bool enable) split on two
> >>>    void device_defer_all_probes_enable(void);
> >>>    void device_defer_all_probes_disable(void);
> >>> - more comments added
> >>>
> >>> Link on v1:
> >>> - https://lkml.org/lkml/2015/10/8/681
> >>>
> >>>   drivers/base/base.h       |  2 ++
> >>>   drivers/base/dd.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
> >>>   drivers/base/power/main.c | 17 +++++++++++++++++
> >>>   3 files changed, 66 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/base/base.h b/drivers/base/base.h
> >>> index 1782f3a..c332b68 100644
> >>> --- a/drivers/base/base.h
> >>> +++ b/drivers/base/base.h
> >>> @@ -131,6 +131,8 @@ extern void device_remove_groups(struct device *dev,
> >>>   extern char *make_class_name(const char *name, struct kobject *kobj);
> >>>
> >>>   extern int devres_release_all(struct device *dev);
> >>> +extern void device_defer_all_probes_enable(void);
> >>> +extern void device_defer_all_probes_disable(void);
> >>>
> >>>   /* /sys/devices directory */
> >>>   extern struct kset *devices_kset;
> >>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> >>> index be0eb46..b8d9e70 100644
> >>> --- a/drivers/base/dd.c
> >>> +++ b/drivers/base/dd.c
> >>> @@ -55,6 +55,13 @@ static struct workqueue_struct *deferred_wq;
> >>>   static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
> >>>
> >>>   /*
> >>> + * In some cases, like suspend to RAM or hibernation, It might be reasonable
> >>> + * to prohibit probing of devices as it could be unsafe.
> >>> + * Once defer_all_probes is true all drivers probes will be forcibly deferred.
> >>> + */
> >>> +static bool defer_all_probes;
> >>> +
> >>> +/*
> >>>    * deferred_probe_work_func() - Retry probing devices in the active list.
> >>>    */
> >>>   static void deferred_probe_work_func(struct work_struct *work)
> >>> @@ -172,6 +179,30 @@ static void driver_deferred_probe_trigger(void)
> >>>   }
> >>>
> >>>   /**
> >>> + * device_defer_all_probes_enable() - Enable deferring of device's probes
> >>> + *
> >>> + *	It will disable probing of devices and defer their probes.
> >>> + */
> >>> +void device_defer_all_probes_enable(void)
> >>> +{
> >>> +	defer_all_probes = true;
> >>> +	/* sync with probes to avoid races. */
> >>> +	wait_for_device_probe();
> >>> +}
> >>
> >> device_pause_probing()?
> 
> device_stop_probing(). Right?

Or device_block_probing()

> >>
> >>> +/**
> >>> + * device_defer_all_probes_disable() - Disable deferring of device's probes
> >>> + *
> >>> + *	It will restore normal behavior and trigger re-probing of deferred
> >>> + * devices.
> >>> + */
> 
> device_start_probing(). Right?

and device_unblock_probing()

> 
> >>
> >> Hmm. This is not quite a double negative... but it sounds like one.
> >>
> >> device_restart_probing()?
> >
> > I _start/_stop would be fine by me too.
> 
> Ok. So do I need rename/resend it again?

Yes, please.

> Probably, I'll need to wait for -rc1 before resending.

No, you don't.  Please resend when you're ready.

Thanks,
Rafael

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