Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH v2] PM / sleep: prohibit devices probing during suspend/hibernation | Date | Fri, 06 Nov 2015 01:13:35 +0100 |
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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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