Commit 7a8d37a3 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Greg Kroah-Hartman
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PM: Do not acquire device semaphores upfront during suspend 

Remove the code that acquires all device semaphores from the suspend
code path as it causes multiple problems to appear (most notably,
http://bugzilla.kernel.org/show_bug.cgi?id=10030) and revert the
change introduced by commit 4145ed6d
depending on the code being removed.

Remove pm_sleep_lock()/pm_sleep_unlock() from device_add() to avoid
the issue reported at http://bugzilla.kernel.org/show_bug.cgi?id=9874.

It should fix the regreesions reported at:
	http://bugzilla.kernel.org/show_bug.cgi?id=9874
	http://bugzilla.kernel.org/show_bug.cgi?id=10030



Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent a4573c48

drivers/base/core.c

+0 −8
Original line number Diff line number Diff line
@@ -770,13 +770,6 @@ int device_add(struct device *dev) 
	struct class_interface *class_intf;

	int error;



	error = pm_sleep_lock();

	if (error) {

		dev_warn(dev, "Suspicious %s during suspend\n", __FUNCTION__);

		dump_stack();

		return error;

	}



	dev = get_device(dev);

	if (!dev || !strlen(dev->bus_id)) {

		error = -EINVAL;
@@ -843,7 +836,6 @@ int device_add(struct device *dev) 
	}

 Done:

	put_device(dev);

	pm_sleep_unlock();

	return error;

 BusError:

	device_pm_remove(dev);

drivers/base/power/main.c

+16 −90
Original line number Diff line number Diff line
@@ -48,7 +48,6 @@ 
 */



LIST_HEAD(dpm_active);

static LIST_HEAD(dpm_locked);

static LIST_HEAD(dpm_off);

static LIST_HEAD(dpm_off_irq);

static LIST_HEAD(dpm_destroy);
@@ -81,28 +80,6 @@ void device_pm_add(struct device *dev) 
 */

void device_pm_remove(struct device *dev)

{

	/*

	 * If this function is called during a suspend, it will be blocked,

	 * because we're holding the device's semaphore at that time, which may

	 * lead to a deadlock.  In that case we want to print a warning.

	 * However, it may also be called by unregister_dropped_devices() with

	 * the device's semaphore released, in which case the warning should

	 * not be printed.

	 */

	if (down_trylock(&dev->sem)) {

		if (down_read_trylock(&pm_sleep_rwsem)) {

			/* No suspend in progress, wait on dev->sem */

			down(&dev->sem);

			up_read(&pm_sleep_rwsem);

		} else {

			/* Suspend in progress, we may deadlock */

			dev_warn(dev, "Suspicious %s during suspend\n",

				__FUNCTION__);

			dump_stack();

			/* The user has been warned ... */

			down(&dev->sem);

		}

	}

	pr_debug("PM: Removing info for %s:%s\n",

		 dev->bus ? dev->bus->name : "No Bus",

		 kobject_name(&dev->kobj));
@@ -110,7 +87,6 @@ void device_pm_remove(struct device *dev) 
	dpm_sysfs_remove(dev);

	list_del_init(&dev->power.entry);

	mutex_unlock(&dpm_list_mtx);

	up(&dev->sem);

}



/**
@@ -230,6 +206,8 @@ static int resume_device(struct device *dev) 
	TRACE_DEVICE(dev);

	TRACE_RESUME(0);



	down(&dev->sem);



	if (dev->bus && dev->bus->resume) {

		dev_dbg(dev,"resuming\n");

		error = dev->bus->resume(dev);
@@ -245,6 +223,8 @@ static int resume_device(struct device *dev) 
		error = dev->class->resume(dev);

	}



	up(&dev->sem);



	TRACE_RESUME(error);

	return error;

}
@@ -266,7 +246,7 @@ static void dpm_resume(void) 
		struct list_head *entry = dpm_off.next;

		struct device *dev = to_device(entry);



		list_move_tail(entry, &dpm_locked);

		list_move_tail(entry, &dpm_active);

		mutex_unlock(&dpm_list_mtx);

		resume_device(dev);

		mutex_lock(&dpm_list_mtx);
@@ -274,25 +254,6 @@ static void dpm_resume(void) 
	mutex_unlock(&dpm_list_mtx);

}



/**

 *	unlock_all_devices - Release each device's semaphore

 *

 *	Go through the dpm_off list.  Put each device on the dpm_active

 *	list and unlock it.

 */

static void unlock_all_devices(void)

{

	mutex_lock(&dpm_list_mtx);

	while (!list_empty(&dpm_locked)) {

		struct list_head *entry = dpm_locked.prev;

		struct device *dev = to_device(entry);



		list_move(entry, &dpm_active);

		up(&dev->sem);

	}

	mutex_unlock(&dpm_list_mtx);

}



/**

 *	unregister_dropped_devices - Unregister devices scheduled for removal

 *
@@ -305,7 +266,6 @@ static void unregister_dropped_devices(void) 
		struct list_head *entry = dpm_destroy.next;

		struct device *dev = to_device(entry);



		up(&dev->sem);

		mutex_unlock(&dpm_list_mtx);

		/* This also removes the device from the list */

		device_unregister(dev);
@@ -324,7 +284,6 @@ void device_resume(void) 
{

	might_sleep();

	dpm_resume();

	unlock_all_devices();

	unregister_dropped_devices();

	up_write(&pm_sleep_rwsem);

}
@@ -388,18 +347,15 @@ int device_power_down(pm_message_t state) 
		struct list_head *entry = dpm_off.prev;

		struct device *dev = to_device(entry);



		list_del_init(&dev->power.entry);

		error = suspend_device_late(dev, state);

		if (error) {

			printk(KERN_ERR "Could not power down device %s: "

					"error %d\n",

					kobject_name(&dev->kobj), error);

			if (list_empty(&dev->power.entry))

				list_add(&dev->power.entry, &dpm_off);

			break;

		}

		if (list_empty(&dev->power.entry))

			list_add(&dev->power.entry, &dpm_off_irq);

		if (!list_empty(&dev->power.entry))

			list_move(&dev->power.entry, &dpm_off_irq);

	}



	if (!error)
@@ -419,6 +375,8 @@ static int suspend_device(struct device *dev, pm_message_t state) 
{

	int error = 0;



	down(&dev->sem);



	if (dev->power.power_state.event) {

		dev_dbg(dev, "PM: suspend %d-->%d\n",

			dev->power.power_state.event, state.event);
@@ -441,6 +399,9 @@ static int suspend_device(struct device *dev, pm_message_t state) 
		error = dev->bus->suspend(dev, state);

		suspend_report_result(dev->bus->suspend, error);

	}



	up(&dev->sem);



	return error;

}
@@ -461,11 +422,10 @@ static int dpm_suspend(pm_message_t state) 
	int error = 0;



	mutex_lock(&dpm_list_mtx);

	while (!list_empty(&dpm_locked)) {

		struct list_head *entry = dpm_locked.prev;

	while (!list_empty(&dpm_active)) {

		struct list_head *entry = dpm_active.prev;

		struct device *dev = to_device(entry);



		list_del_init(&dev->power.entry);

		mutex_unlock(&dpm_list_mtx);

		error = suspend_device(dev, state);

		if (error) {
@@ -476,50 +436,17 @@ static int dpm_suspend(pm_message_t state) 
					(error == -EAGAIN ?

					" (please convert to suspend_late)" :

					""));

			mutex_lock(&dpm_list_mtx);

			if (list_empty(&dev->power.entry))

				list_add(&dev->power.entry, &dpm_locked);

			break;

		}

		mutex_lock(&dpm_list_mtx);

		if (list_empty(&dev->power.entry))

			list_add(&dev->power.entry, &dpm_off);

		if (!list_empty(&dev->power.entry))

			list_move(&dev->power.entry, &dpm_off);

	}

	mutex_unlock(&dpm_list_mtx);



	return error;

}



/**

 *	lock_all_devices - Acquire every device's semaphore

 *

 *	Go through the dpm_active list. Carefully lock each device's

 *	semaphore and put it in on the dpm_locked list.

 */

static void lock_all_devices(void)

{

	mutex_lock(&dpm_list_mtx);

	while (!list_empty(&dpm_active)) {

		struct list_head *entry = dpm_active.next;

		struct device *dev = to_device(entry);



		/* Required locking order is dev->sem first,

		 * then dpm_list_mutex.  Hence this awkward code.

		 */

		get_device(dev);

		mutex_unlock(&dpm_list_mtx);

		down(&dev->sem);

		mutex_lock(&dpm_list_mtx);



		if (list_empty(entry))

			up(&dev->sem);		/* Device was removed */

		else

			list_move_tail(entry, &dpm_locked);

		put_device(dev);

	}

	mutex_unlock(&dpm_list_mtx);

}



/**

 *	device_suspend - Save state and stop all devices in system.

 *	@state: new power management state
@@ -533,7 +460,6 @@ int device_suspend(pm_message_t state) 


	might_sleep();

	down_write(&pm_sleep_rwsem);

	lock_all_devices();

	error = dpm_suspend(state);

	if (error)

		device_resume();

drivers/usb/core/usb.c

+1 −1
Original line number Diff line number Diff line
@@ -233,7 +233,7 @@ static int ksuspend_usb_init(void) 
	 * singlethreaded.  Its job doesn't justify running on more

	 * than one CPU.

	 */

	ksuspend_usb_wq = create_singlethread_workqueue("ksuspend_usbd");

	ksuspend_usb_wq = create_freezeable_workqueue("ksuspend_usbd");

	if (!ksuspend_usb_wq)

		return -ENOMEM;

	return 0;

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