Commit e8b364b8 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
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PM / Clocks: Do not acquire a mutex under a spinlock 



Commit b7ab83ed (PM: Use spinlock instead of mutex in clock
management functions) introduced a regression causing clocks_mutex
to be acquired under a spinlock.  This happens because
pm_clk_suspend() and pm_clk_resume() call pm_clk_acquire() under
pcd->lock, but pm_clk_acquire() executes clk_get() which causes
clocks_mutex to be acquired.  Similarly, __pm_clk_remove(),
executed under pcd->lock, calls clk_put(), which also causes
clocks_mutex to be acquired.

To fix those problems make pm_clk_add() call pm_clk_acquire(), so
that pm_clk_suspend() and pm_clk_resume() don't have to do that.
Change pm_clk_remove() and pm_clk_destroy() to separate
modifications of the pcd->clock_list list from the actual removal of
PM clock entry objects done by __pm_clk_remove().

Reported-and-tested-by: default avatarGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent f9d81f61

drivers/base/power/clock_ops.c

+38 −37
Original line number Diff line number Diff line
@@ -41,6 +41,22 @@ static struct pm_clk_data *__to_pcd(struct device *dev) 
	return dev ? dev->power.subsys_data : NULL;

}



/**

 * pm_clk_acquire - Acquire a device clock.

 * @dev: Device whose clock is to be acquired.

 * @ce: PM clock entry corresponding to the clock.

 */

static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)

{

	ce->clk = clk_get(dev, ce->con_id);

	if (IS_ERR(ce->clk)) {

		ce->status = PCE_STATUS_ERROR;

	} else {

		ce->status = PCE_STATUS_ACQUIRED;

		dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id);

	}

}



/**

 * pm_clk_add - Start using a device clock for power management.

 * @dev: Device whose clock is going to be used for power management.
@@ -73,6 +89,8 @@ int pm_clk_add(struct device *dev, const char *con_id) 
		}

	}



	pm_clk_acquire(dev, ce);



	spin_lock_irq(&pcd->lock);

	list_add_tail(&ce->node, &pcd->clock_list);

	spin_unlock_irq(&pcd->lock);
@@ -82,17 +100,12 @@ int pm_clk_add(struct device *dev, const char *con_id) 
/**

 * __pm_clk_remove - Destroy PM clock entry.

 * @ce: PM clock entry to destroy.

 *

 * This routine must be called under the spinlock protecting the PM list of

 * clocks corresponding the the @ce's device.

 */

static void __pm_clk_remove(struct pm_clock_entry *ce)

{

	if (!ce)

		return;



	list_del(&ce->node);



	if (ce->status < PCE_STATUS_ERROR) {

		if (ce->status == PCE_STATUS_ENABLED)

			clk_disable(ce->clk);
@@ -126,18 +139,22 @@ void pm_clk_remove(struct device *dev, const char *con_id) 
	spin_lock_irq(&pcd->lock);



	list_for_each_entry(ce, &pcd->clock_list, node) {

		if (!con_id && !ce->con_id) {

			__pm_clk_remove(ce);

			break;

		} else if (!con_id || !ce->con_id) {

		if (!con_id && !ce->con_id)

			goto remove;

		else if (!con_id || !ce->con_id)

			continue;

		} else if (!strcmp(con_id, ce->con_id)) {

			__pm_clk_remove(ce);

			break;

		}

		else if (!strcmp(con_id, ce->con_id))

			goto remove;

	}



	spin_unlock_irq(&pcd->lock);

	return;



 remove:

	list_del(&ce->node);

	spin_unlock_irq(&pcd->lock);



	__pm_clk_remove(ce);

}



/**
@@ -175,43 +192,33 @@ void pm_clk_destroy(struct device *dev) 
{

	struct pm_clk_data *pcd = __to_pcd(dev);

	struct pm_clock_entry *ce, *c;

	struct list_head list;



	if (!pcd)

		return;



	dev->power.subsys_data = NULL;

	INIT_LIST_HEAD(&list);



	spin_lock_irq(&pcd->lock);



	list_for_each_entry_safe_reverse(ce, c, &pcd->clock_list, node)

		__pm_clk_remove(ce);

		list_move(&ce->node, &list);



	spin_unlock_irq(&pcd->lock);



	kfree(pcd);



	list_for_each_entry_safe_reverse(ce, c, &list, node) {

		list_del(&ce->node);

		__pm_clk_remove(ce);

	}

}



#endif /* CONFIG_PM */



#ifdef CONFIG_PM_RUNTIME



/**

 * pm_clk_acquire - Acquire a device clock.

 * @dev: Device whose clock is to be acquired.

 * @con_id: Connection ID of the clock.

 */

static void pm_clk_acquire(struct device *dev,

				    struct pm_clock_entry *ce)

{

	ce->clk = clk_get(dev, ce->con_id);

	if (IS_ERR(ce->clk)) {

		ce->status = PCE_STATUS_ERROR;

	} else {

		ce->status = PCE_STATUS_ACQUIRED;

		dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id);

	}

}



/**

 * pm_clk_suspend - Disable clocks in a device's PM clock list.

 * @dev: Device to disable the clocks for.
@@ -230,9 +237,6 @@ int pm_clk_suspend(struct device *dev) 
	spin_lock_irqsave(&pcd->lock, flags);



	list_for_each_entry_reverse(ce, &pcd->clock_list, node) {

		if (ce->status == PCE_STATUS_NONE)

			pm_clk_acquire(dev, ce);



		if (ce->status < PCE_STATUS_ERROR) {

			clk_disable(ce->clk);

			ce->status = PCE_STATUS_ACQUIRED;
@@ -262,9 +266,6 @@ int pm_clk_resume(struct device *dev) 
	spin_lock_irqsave(&pcd->lock, flags);



	list_for_each_entry(ce, &pcd->clock_list, node) {

		if (ce->status == PCE_STATUS_NONE)

			pm_clk_acquire(dev, ce);



		if (ce->status < PCE_STATUS_ERROR) {

			clk_enable(ce->clk);

			ce->status = PCE_STATUS_ENABLED;

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