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authorRafael J. Wysocki <rjw@sisk.pl>2011-05-17 23:26:00 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2011-05-17 23:26:00 +0200
commit91e7c75ba93c48a82670d630b9daac92ff70095d (patch)
treeb44ac3dca1d03cce99cccc3f4ce55d4b5475d373 /drivers/base/power/main.c
parentc650da23d59d2c82307380414606774c6d49b8bd (diff)
PM: Allow drivers to allocate memory from .prepare() callbacks safely
If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'drivers/base/power/main.c')
-rw-r--r--drivers/base/power/main.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 3b354560f306..aa6320207745 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -579,11 +579,13 @@ static bool is_async(struct device *dev)
* Execute the appropriate "resume" callback for all devices whose status
* indicates that they are suspended.
*/
-static void dpm_resume(pm_message_t state)
+void dpm_resume(pm_message_t state)
{
struct device *dev;
ktime_t starttime = ktime_get();
+ might_sleep();
+
mutex_lock(&dpm_list_mtx);
pm_transition = state;
async_error = 0;
@@ -656,10 +658,12 @@ static void device_complete(struct device *dev, pm_message_t state)
* Execute the ->complete() callbacks for all devices whose PM status is not
* DPM_ON (this allows new devices to be registered).
*/
-static void dpm_complete(pm_message_t state)
+void dpm_complete(pm_message_t state)
{
struct list_head list;
+ might_sleep();
+
INIT_LIST_HEAD(&list);
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_prepared_list)) {
@@ -688,7 +692,6 @@ static void dpm_complete(pm_message_t state)
*/
void dpm_resume_end(pm_message_t state)
{
- might_sleep();
dpm_resume(state);
dpm_complete(state);
}
@@ -912,11 +915,13 @@ static int device_suspend(struct device *dev)
* dpm_suspend - Execute "suspend" callbacks for all non-sysdev devices.
* @state: PM transition of the system being carried out.
*/
-static int dpm_suspend(pm_message_t state)
+int dpm_suspend(pm_message_t state)
{
ktime_t starttime = ktime_get();
int error = 0;
+ might_sleep();
+
mutex_lock(&dpm_list_mtx);
pm_transition = state;
async_error = 0;
@@ -1003,10 +1008,12 @@ static int device_prepare(struct device *dev, pm_message_t state)
*
* Execute the ->prepare() callback(s) for all devices.
*/
-static int dpm_prepare(pm_message_t state)
+int dpm_prepare(pm_message_t state)
{
int error = 0;
+ might_sleep();
+
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_list)) {
struct device *dev = to_device(dpm_list.next);
@@ -1055,7 +1062,6 @@ int dpm_suspend_start(pm_message_t state)
{
int error;
- might_sleep();
error = dpm_prepare(state);
if (!error)
error = dpm_suspend(state);