PM / sleep: prohibit devices probing during suspend/hibernation (013c074f) · Commits · 戴 / test

drivers/base/base.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -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_block_probing(void);
		extern void device_unblock_probing(void);

		/* /sys/devices directory */
		extern struct kset *devices_kset;

drivers/base/dd.c

+47 −1

Original line number	Diff line number	Diff line
		@@ -54,6 +54,13 @@ static LIST_HEAD(deferred_probe_active_list);
		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.
		*/
		@@ -171,6 +178,30 @@ static void driver_deferred_probe_trigger(void)
		queue_work(deferred_wq, &deferred_probe_work);
		}

		/**
		* device_block_probing() - Block/defere device's probes
		*
		* It will disable probing of devices and defer their probes instead.
		*/
		void device_block_probing(void)
		{
		defer_all_probes = true;
		/* sync with probes to avoid races. */
		wait_for_device_probe();
		}

		/**
		* device_unblock_probing() - Unblock/enable device's probes
		*
		* It will restore normal behavior and trigger re-probing of deferred
		* devices.
		*/
		void device_unblock_probing(void)
		{
		defer_all_probes = false;
		driver_deferred_probe_trigger();
		}

		/**
		* deferred_probe_initcall() - Enable probing of deferred devices
		*
		@@ -277,9 +308,20 @@ static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);

		static int really_probe(struct device dev, struct device_driver drv)
		{
		int ret = 0;
		int ret = -EPROBE_DEFER;
		int local_trigger_count = atomic_read(&deferred_trigger_count);

		if (defer_all_probes) {
		/*
		* Value of defer_all_probes can be set only by
		* device_defer_all_probes_enable() which, in turn, will call
		* wait_for_device_probe() right after that to avoid any races.
		*/
		dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
		driver_deferred_probe_add(dev);
		return ret;
		}

		atomic_inc(&probe_count);
		pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
		drv->bus->name, __func__, drv->name, dev_name(dev));
		@@ -393,6 +435,10 @@ int driver_probe_done(void)
		*/
		void wait_for_device_probe(void)
		{
		/* wait for the deferred probe workqueue to finish */
		if (driver_deferred_probe_enable)
		flush_workqueue(deferred_wq);

		/* wait for the known devices to complete their probing */
		wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
		async_synchronize_full();

drivers/base/power/main.c

+17 −0

Original line number	Diff line number	Diff line
		@@ -963,6 +963,9 @@ void dpm_complete(pm_message_t state)
		}
		list_splice(&list, &dpm_list);
		mutex_unlock(&dpm_list_mtx);

		/* Allow device probing and trigger re-probing of deferred devices */
		device_unblock_probing();
		trace_suspend_resume(TPS("dpm_complete"), state.event, false);
		}

		@@ -1624,6 +1627,20 @@ int dpm_prepare(pm_message_t state)
		trace_suspend_resume(TPS("dpm_prepare"), state.event, true);
		might_sleep();

		/*
		* Give a chance for the known devices to complete their probes, before
		* disable probing of devices. This sync point is important at least
		* at boot time + hibernation restore.
		*/
		wait_for_device_probe();
		/*
		* It is unsafe if probing of devices will happen during suspend or
		* hibernation and system behavior will be unpredictable in this case.
		* So, let's prohibit device's probing here and defer their probes
		* instead. The normal behavior will be restored in dpm_complete().
		*/
		device_block_probing();

		mutex_lock(&dpm_list_mtx);
		while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.next);

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