linux-kernel - [PATCH] PM: runtime: add might

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Date:	Fri, 22 Jul 2011 21:56:07 -0700
From:	Colin Cross <ccross@...roid.com>
To:	linux-pm@...ts.linux-foundation.org
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org,
	Kevin Hilman <khilman@...com>, Nishanth Menon <nm@...com>,
	Colin Cross <ccross@...roid.com>
Subject: [PATCH] PM: runtime: add might_sleep to PM runtime functions

The list of functions that can be called in atomic context is
non-intuitive (pm_runtime_put_sync can not, but
pm_runtime_put_sync_suspend can, if pm_runtime_irq_safe has
been called?).  The code is actively misleading - the entry
points all start with spin_lock_irqsave, suggesting they
are safe to call in atomic context, but may later
enable interrupts.

Add might_sleep_if to all the __pm_runtime_* entry points
to enforce correct usage.

Also add pm_runtime_put_sync_autosuspend to the list of
functions that can be called in atomic context.

Signed-off-by: Colin Cross <ccross@...roid.com>
---
 Documentation/power/runtime_pm.txt |    1 +
 drivers/base/power/runtime.c       |   16 ++++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index b24875b..22852b3 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -469,6 +469,7 @@ pm_runtime_autosuspend()
 pm_runtime_resume()
 pm_runtime_get_sync()
 pm_runtime_put_sync_suspend()
+pm_runtime_put_sync_autosuspend()
 
 5. Run-time PM Initialization, Device Probing and Removal
 
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 0d4587b..fdc4567 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -732,6 +732,8 @@ int __pm_runtime_idle(struct device *dev, int rpmflags)
 	unsigned long flags;
 	int retval;
 
+	might_sleep_if(!(rpmflags & RPM_ASYNC));
+
 	if (rpmflags & RPM_GET_PUT) {
 		if (!atomic_dec_and_test(&dev->power.usage_count))
 			return 0;
@@ -754,13 +756,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_idle);
  * return immediately if it is larger than zero.  Then carry out a suspend,
  * either synchronous or asynchronous.
  *
- * This routine may be called in atomic context if the RPM_ASYNC flag is set.
+ * This routine may be called in atomic context if the RPM_ASYNC flag is set,
+ * or if pm_runtime_irq_safe() has been called.
  */
 int __pm_runtime_suspend(struct device *dev, int rpmflags)
 {
 	unsigned long flags;
 	int retval;
 
+	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
+
 	if (rpmflags & RPM_GET_PUT) {
 		if (!atomic_dec_and_test(&dev->power.usage_count))
 			return 0;
@@ -782,13 +787,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
  * carry out a resume, either synchronous or asynchronous.
  *
- * This routine may be called in atomic context if the RPM_ASYNC flag is set.
+ * This routine may be called in atomic context if the RPM_ASYNC flag is set,
+ * or if pm_runtime_irq_safe() has been called.
  */
 int __pm_runtime_resume(struct device *dev, int rpmflags)
 {
 	unsigned long flags;
 	int retval;
 
+	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
+
 	if (rpmflags & RPM_GET_PUT)
 		atomic_inc(&dev->power.usage_count);
 
@@ -978,6 +986,8 @@ EXPORT_SYMBOL_GPL(pm_runtime_barrier);
  */
 void __pm_runtime_disable(struct device *dev, bool check_resume)
 {
+	might_sleep();
+
 	spin_lock_irq(&dev->power.lock);
 
 	if (dev->power.disable_depth > 0) {
@@ -1184,6 +1194,8 @@ void __pm_runtime_use_autosuspend(struct device *dev, bool use)
 {
 	int old_delay, old_use;
 
+	might_sleep();
+
 	spin_lock_irq(&dev->power.lock);
 	old_delay = dev->power.autosuspend_delay;
 	old_use = dev->power.use_autosuspend;
-- 
1.7.4.1

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