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PM / Clocks: Do not acquire a mutex under a spinlock

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Commit b7ab83e (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: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Rafael J. Wysocki 2011-09-26 19:40:23 +02:00
parent f9d81f61c8
commit e8b364b88c
1 changed files with 38 additions and 37 deletions
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75
drivers/base/power/clock_ops.c
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@ -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;