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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>
This commit is contained in:
Rafael J. Wysocki 2010-09-22 22:10:57 +02:00
parent 074037ec79
commit 098dff738a
2 changed files with 14 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/base/power/main.c
View File

@ -51,6 +51,8 @@ static pm_message_t pm_transition;
*/
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 @@ static void dpm_resume(pm_message_t state)
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 @@ static int legacy_suspend(struct device *dev, pm_message_t state,
return error;
}
static int async_error;
/**
* device_suspend - Execute "suspend" callbacks for given device.
* @dev: Device to handle.
@ -887,6 +888,9 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
device_unlock(dev);
complete_all(&dev->power.completion);
if (error)
async_error = error;
return error;
}
@ -896,10 +900,8 @@ static void async_suspend(void *data, async_cookie_t cookie)
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 @@ EXPORT_SYMBOL_GPL(__suspend_report_result);
* @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);

7
include/linux/pm.h
View File

@ -559,7 +559,7 @@ extern void __suspend_report_result(const char *function, void *fn, int ret);
__suspend_report_result(__func__, fn, ret); \
} while (0)
extern void device_pm_wait_for_dev(struct device *sub, struct device *dev);
extern int device_pm_wait_for_dev(struct device *sub, struct device *dev);
#else /* !CONFIG_PM_SLEEP */
#define device_pm_lock() do {} while (0)
@ -572,7 +572,10 @@ static inline int dpm_suspend_start(pm_message_t state)
#define suspend_report_result(fn, ret) do {} while (0)
static inline void device_pm_wait_for_dev(struct device *a, struct device *b) {}
static inline int device_pm_wait_for_dev(struct device *a, struct device *b)
{
return 0;
}
#endif /* !CONFIG_PM_SLEEP */
/* How to reorder dpm_list after device_move() */