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 23:44:48 +0100 |
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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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