PM: Fix async resume following suspend failure
Alan Stern [Sat, 18 Jun 2011 20:42:09 +0000 (22:42 +0200)]
The PM core doesn't handle suspend failures correctly when it comes to
asynchronously suspended devices.  These devices are moved onto the
dpm_suspended_list as soon as the corresponding async thread is
started up, and they remain on the list even if they fail to suspend
or the sleep transition is cancelled before they get suspended.  As a
result, when the PM core unwinds the transition, it tries to resume
the devices even though they were never suspended.

This patch (as1474) fixes the problem by adding a new "is_suspended"
flag to dev_pm_info.  Devices are resumed only if the flag is set.

[rjw:
 * Moved the dev->power.is_suspended check into device_resume(),
   because we need to complete dev->power.completion and clear
   dev->power.is_prepared too for devices whose
   dev->power.is_suspended flags are unset.
 * Fixed __device_suspend() to avoid setting dev->power.is_suspended
   if async_error is different from zero.]

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@kernel.org

drivers/base/power/main.c
include/linux/pm.h

index bf5a59a..06f09bf 100644 (file)
@@ -58,6 +58,7 @@ static int async_error;
 void device_pm_init(struct device *dev)
 {
        dev->power.is_prepared = false;
+       dev->power.is_suspended = false;
        init_completion(&dev->power.completion);
        complete_all(&dev->power.completion);
        dev->power.wakeup = NULL;
@@ -517,6 +518,9 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
         */
        dev->power.is_prepared = false;
 
+       if (!dev->power.is_suspended)
+               goto Unlock;
+
        if (dev->pwr_domain) {
                pm_dev_dbg(dev, state, "power domain ");
                error = pm_op(dev, &dev->pwr_domain->ops, state);
@@ -552,6 +556,9 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
        }
 
  End:
+       dev->power.is_suspended = false;
+
+ Unlock:
        device_unlock(dev);
        complete_all(&dev->power.completion);
 
@@ -839,11 +846,11 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
        device_lock(dev);
 
        if (async_error)
-               goto End;
+               goto Unlock;
 
        if (pm_wakeup_pending()) {
                async_error = -EBUSY;
-               goto End;
+               goto Unlock;
        }
 
        if (dev->pwr_domain) {
@@ -881,6 +888,9 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
        }
 
  End:
+       dev->power.is_suspended = !error;
+
+ Unlock:
        device_unlock(dev);
        complete_all(&dev->power.completion);
 
index cc536bd..411e4f4 100644 (file)
@@ -426,6 +426,7 @@ struct dev_pm_info {
        unsigned int            can_wakeup:1;
        unsigned int            async_suspend:1;
        bool                    is_prepared:1;  /* Owned by the PM core */
+       bool                    is_suspended:1; /* Ditto */
        spinlock_t              lock;
 #ifdef CONFIG_PM_SLEEP
        struct list_head        entry;