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 <st...@rowland.harvard.edu>
Cc: Rafael J. Wysocki <r...@rjwysocki.net>
Cc: Thierry Reding <thierry.red...@gmail.com>
Signed-off-by: Grygorii Strashko <grygorii.stras...@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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