PM / Runtime: Don't run callbacks under lock for power.irq_safe set
Rafael J. Wysocki [Tue, 27 Sep 2011 19:54:52 +0000 (21:54 +0200)]
The rpm_suspend() and rpm_resume() routines execute subsystem or PM
domain callbacks under power.lock if power.irq_safe is set for the
given device.  This is inconsistent with that rpm_idle() does after
commit 02b2677 (PM / Runtime: Allow _put_sync() from
interrupts-disabled context) and is problematic for subsystems and PM
domains wanting to use power.lock for synchronization in their
runtime PM callbacks.

This change requires the code checking if the device's runtime PM
status is RPM_SUSPENDING or RPM_RESUMING to be modified too, to take
the power.irq_safe set case into account (that code wasn't reachable
before with power.irq_safe set, because it's executed with the
device's power.lock held).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>

drivers/base/power/runtime.c

index 04e18ab..aecb2a8 100644 (file)
@@ -155,6 +155,31 @@ static int rpm_check_suspend_allowed(struct device *dev)
 }
 
 /**
+ * __rpm_callback - Run a given runtime PM callback for a given device.
+ * @cb: Runtime PM callback to run.
+ * @dev: Device to run the callback for.
+ */
+static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
+       __releases(&dev->power.lock) __acquires(&dev->power.lock)
+{
+       int retval;
+
+       if (dev->power.irq_safe)
+               spin_unlock(&dev->power.lock);
+       else
+               spin_unlock_irq(&dev->power.lock);
+
+       retval = cb(dev);
+
+       if (dev->power.irq_safe)
+               spin_lock(&dev->power.lock);
+       else
+               spin_lock_irq(&dev->power.lock);
+
+       return retval;
+}
+
+/**
  * rpm_idle - Notify device bus type if the device can be suspended.
  * @dev: Device to notify the bus type about.
  * @rpmflags: Flag bits.
@@ -225,19 +250,8 @@ static int rpm_idle(struct device *dev, int rpmflags)
        else
                callback = NULL;
 
-       if (callback) {
-               if (dev->power.irq_safe)
-                       spin_unlock(&dev->power.lock);
-               else
-                       spin_unlock_irq(&dev->power.lock);
-
-               callback(dev);
-
-               if (dev->power.irq_safe)
-                       spin_lock(&dev->power.lock);
-               else
-                       spin_lock_irq(&dev->power.lock);
-       }
+       if (callback)
+               __rpm_callback(callback, dev);
 
        dev->power.idle_notification = false;
        wake_up_all(&dev->power.wait_queue);
@@ -252,22 +266,14 @@ static int rpm_idle(struct device *dev, int rpmflags)
  * @dev: Device to run the callback for.
  */
 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
-       __releases(&dev->power.lock) __acquires(&dev->power.lock)
 {
        int retval;
 
        if (!cb)
                return -ENOSYS;
 
-       if (dev->power.irq_safe) {
-               retval = cb(dev);
-       } else {
-               spin_unlock_irq(&dev->power.lock);
-
-               retval = cb(dev);
+       retval = __rpm_callback(cb, dev);
 
-               spin_lock_irq(&dev->power.lock);
-       }
        dev->power.runtime_error = retval;
        return retval != -EACCES ? retval : -EIO;
 }
@@ -347,6 +353,15 @@ static int rpm_suspend(struct device *dev, int rpmflags)
                        goto out;
                }
 
+               if (dev->power.irq_safe) {
+                       spin_unlock(&dev->power.lock);
+
+                       cpu_relax();
+
+                       spin_lock(&dev->power.lock);
+                       goto repeat;
+               }
+
                /* Wait for the other suspend running in parallel with us. */
                for (;;) {
                        prepare_to_wait(&dev->power.wait_queue, &wait,
@@ -496,6 +511,15 @@ static int rpm_resume(struct device *dev, int rpmflags)
                        goto out;
                }
 
+               if (dev->power.irq_safe) {
+                       spin_unlock(&dev->power.lock);
+
+                       cpu_relax();
+
+                       spin_lock(&dev->power.lock);
+                       goto repeat;
+               }
+
                /* Wait for the operation carried out in parallel with us. */
                for (;;) {
                        prepare_to_wait(&dev->power.wait_queue, &wait,