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authorRafael J. Wysocki <rjw@sisk.pl>2008-03-12 00:57:22 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2008-04-19 19:10:24 -0700
commit58aca23226a19983571bd3b65167521fc64f5869 (patch)
tree1fd3f54ce5f18dc972b77970289a27a4e4a39bee /drivers/base/power
parent6bcf19d02a5d7e627fa054f2f10e0a8d830df326 (diff)
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PM: Handle device registrations during suspend/resume
Modify the PM core to protect its data structures, specifically the dpm_active list, from being corrupted if a child of the currently suspending device is registered concurrently with its ->suspend() callback. In that case, since the new device (the child) is added to dpm_active after its parent, the PM core will attempt to suspend it after the parent, which is wrong. Introduce a new member of struct dev_pm_info, called 'sleeping', and use it to check if the parent of the device being added to dpm_active has been suspended, in which case the device registration fails. Also, use 'sleeping' for checking if the ordering of devices on dpm_active is correct. Introduce variable 'all_sleeping' that will be set to 'true' once all devices have been suspended and make new device registrations fail until 'all_sleeping' is reset to 'false', in order to avoid having unsuspended devices around while the system is going into a sleep state. Remove pm_sleep_rwsem which is not necessary any more. Special thanks to Alan Stern for discussions and suggestions that lead to the creation of this patch. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/base/power')
-rw-r--r--drivers/base/power/main.c57
-rw-r--r--drivers/base/power/power.h23
2 files changed, 29 insertions, 51 deletions
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 26de2c0..0e3991a 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -54,7 +54,8 @@ static LIST_HEAD(dpm_destroy);
static DEFINE_MUTEX(dpm_list_mtx);
-static DECLARE_RWSEM(pm_sleep_rwsem);
+/* 'true' if all devices have been suspended, protected by dpm_list_mtx */
+static bool all_sleeping;
int (*platform_enable_wakeup)(struct device *dev, int is_on);
@@ -62,14 +63,28 @@ int (*platform_enable_wakeup)(struct device *dev, int is_on);
* device_pm_add - add a device to the list of active devices
* @dev: Device to be added to the list
*/
-void device_pm_add(struct device *dev)
+int device_pm_add(struct device *dev)
{
+ int error = 0;
+
pr_debug("PM: Adding info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus",
kobject_name(&dev->kobj));
mutex_lock(&dpm_list_mtx);
- list_add_tail(&dev->power.entry, &dpm_active);
+ if ((dev->parent && dev->parent->power.sleeping) || all_sleeping) {
+ if (dev->parent->power.sleeping)
+ dev_warn(dev,
+ "parent %s is sleeping, will not add\n",
+ dev->parent->bus_id);
+ else
+ dev_warn(dev, "devices are sleeping, will not add\n");
+ WARN_ON(true);
+ error = -EBUSY;
+ } else {
+ list_add_tail(&dev->power.entry, &dpm_active);
+ }
mutex_unlock(&dpm_list_mtx);
+ return error;
}
/**
@@ -107,32 +122,6 @@ void device_pm_schedule_removal(struct device *dev)
}
EXPORT_SYMBOL_GPL(device_pm_schedule_removal);
-/**
- * pm_sleep_lock - mutual exclusion for registration and suspend
- *
- * Returns 0 if no suspend is underway and device registration
- * may proceed, otherwise -EBUSY.
- */
-int pm_sleep_lock(void)
-{
- if (down_read_trylock(&pm_sleep_rwsem))
- return 0;
-
- return -EBUSY;
-}
-
-/**
- * pm_sleep_unlock - mutual exclusion for registration and suspend
- *
- * This routine undoes the effect of device_pm_add_lock
- * when a device's registration is complete.
- */
-void pm_sleep_unlock(void)
-{
- up_read(&pm_sleep_rwsem);
-}
-
-
/*------------------------- Resume routines -------------------------*/
/**
@@ -242,11 +231,13 @@ static int resume_device(struct device *dev)
static void dpm_resume(void)
{
mutex_lock(&dpm_list_mtx);
+ all_sleeping = false;
while(!list_empty(&dpm_off)) {
struct list_head *entry = dpm_off.next;
struct device *dev = to_device(entry);
list_move_tail(entry, &dpm_active);
+ dev->power.sleeping = false;
mutex_unlock(&dpm_list_mtx);
resume_device(dev);
mutex_lock(&dpm_list_mtx);
@@ -285,7 +276,6 @@ void device_resume(void)
might_sleep();
dpm_resume();
unregister_dropped_devices();
- up_write(&pm_sleep_rwsem);
}
EXPORT_SYMBOL_GPL(device_resume);
@@ -421,6 +411,9 @@ static int dpm_suspend(pm_message_t state)
struct list_head *entry = dpm_active.prev;
struct device *dev = to_device(entry);
+ WARN_ON(dev->parent && dev->parent->power.sleeping);
+
+ dev->power.sleeping = true;
mutex_unlock(&dpm_list_mtx);
error = suspend_device(dev, state);
mutex_lock(&dpm_list_mtx);
@@ -432,11 +425,14 @@ static int dpm_suspend(pm_message_t state)
(error == -EAGAIN ?
" (please convert to suspend_late)" :
""));
+ dev->power.sleeping = false;
break;
}
if (!list_empty(&dev->power.entry))
list_move(&dev->power.entry, &dpm_off);
}
+ if (!error)
+ all_sleeping = true;
mutex_unlock(&dpm_list_mtx);
return error;
@@ -454,7 +450,6 @@ int device_suspend(pm_message_t state)
int error;
might_sleep();
- down_write(&pm_sleep_rwsem);
error = dpm_suspend(state);
if (error)
device_resume();
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index e32d3bd..a6894f2 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -11,30 +11,13 @@ static inline struct device *to_device(struct list_head *entry)
return container_of(entry, struct device, power.entry);
}
-extern void device_pm_add(struct device *);
+extern int device_pm_add(struct device *);
extern void device_pm_remove(struct device *);
-extern int pm_sleep_lock(void);
-extern void pm_sleep_unlock(void);
#else /* CONFIG_PM_SLEEP */
-
-static inline void device_pm_add(struct device *dev)
-{
-}
-
-static inline void device_pm_remove(struct device *dev)
-{
-}
-
-static inline int pm_sleep_lock(void)
-{
- return 0;
-}
-
-static inline void pm_sleep_unlock(void)
-{
-}
+static inline int device_pm_add(struct device *dev) { return 0; }
+static inline void device_pm_remove(struct device *dev) {}
#endif