PM: Fix potential issue with failing asynchronous suspend
There is a potential issue with the asynchronous suspend code that
a device driver suspending asynchronously may not notice that it
should back off. There are two failing scenarions, (1) when the
driver is waiting for a driver suspending synchronously to complete
and that second driver returns error code, in which case async_error
won't be set and the waiting driver will continue suspending and (2)
after the driver has called device_pm_wait_for_dev() and the waited
for driver returns error code, in which case the caller of
device_pm_wait_for_dev() will not know that there was an error and
will continue suspending.
To fix this issue make __device_suspend() set async_error, so
async_suspend() doesn't need to set it any more, and make
device_pm_wait_for_dev() return async_error, so that its callers
can check whether or not they should continue suspending.
No more changes are necessary, since device_pm_wait_for_dev() is
not used by any drivers' suspend routines.
Reported-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 7ae6fe4..31b5266 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -51,6 +51,8 @@
*/
static bool transition_started;
+static int async_error;
+
/**
* device_pm_init - Initialize the PM-related part of a device object.
* @dev: Device object being initialized.
@@ -602,6 +604,7 @@
INIT_LIST_HEAD(&list);
mutex_lock(&dpm_list_mtx);
pm_transition = state;
+ async_error = 0;
list_for_each_entry(dev, &dpm_list, power.entry) {
if (dev->power.status < DPM_OFF)
@@ -831,8 +834,6 @@
return error;
}
-static int async_error;
-
/**
* device_suspend - Execute "suspend" callbacks for given device.
* @dev: Device to handle.
@@ -887,6 +888,9 @@
device_unlock(dev);
complete_all(&dev->power.completion);
+ if (error)
+ async_error = error;
+
return error;
}
@@ -896,10 +900,8 @@
int error;
error = __device_suspend(dev, pm_transition, true);
- if (error) {
+ if (error)
pm_dev_err(dev, pm_transition, " async", error);
- async_error = error;
- }
put_device(dev);
}
@@ -1087,8 +1089,9 @@
* @dev: Device to wait for.
* @subordinate: Device that needs to wait for @dev.
*/
-void device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
+int device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
{
dpm_wait(dev, subordinate->power.async_suspend);
+ return async_error;
}
EXPORT_SYMBOL_GPL(device_pm_wait_for_dev);