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>
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@ -51,6 +51,8 @@ static pm_message_t pm_transition;
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*/
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*/
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static bool transition_started;
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static bool transition_started;
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static int async_error;
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/**
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/**
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* device_pm_init - Initialize the PM-related part of a device object.
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* device_pm_init - Initialize the PM-related part of a device object.
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* @dev: Device object being initialized.
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* @dev: Device object being initialized.
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@ -602,6 +604,7 @@ static void dpm_resume(pm_message_t state)
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INIT_LIST_HEAD(&list);
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INIT_LIST_HEAD(&list);
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mutex_lock(&dpm_list_mtx);
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mutex_lock(&dpm_list_mtx);
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pm_transition = state;
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pm_transition = state;
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async_error = 0;
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list_for_each_entry(dev, &dpm_list, power.entry) {
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list_for_each_entry(dev, &dpm_list, power.entry) {
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if (dev->power.status < DPM_OFF)
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if (dev->power.status < DPM_OFF)
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@ -831,8 +834,6 @@ static int legacy_suspend(struct device *dev, pm_message_t state,
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return error;
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return error;
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}
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}
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static int async_error;
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/**
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/**
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* device_suspend - Execute "suspend" callbacks for given device.
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* device_suspend - Execute "suspend" callbacks for given device.
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* @dev: Device to handle.
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* @dev: Device to handle.
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@ -887,6 +888,9 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
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device_unlock(dev);
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device_unlock(dev);
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complete_all(&dev->power.completion);
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complete_all(&dev->power.completion);
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if (error)
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async_error = error;
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return error;
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return error;
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}
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}
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@ -896,10 +900,8 @@ static void async_suspend(void *data, async_cookie_t cookie)
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int error;
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int error;
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error = __device_suspend(dev, pm_transition, true);
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error = __device_suspend(dev, pm_transition, true);
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if (error) {
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if (error)
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pm_dev_err(dev, pm_transition, " async", error);
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pm_dev_err(dev, pm_transition, " async", error);
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async_error = error;
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}
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put_device(dev);
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put_device(dev);
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}
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}
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@ -1087,8 +1089,9 @@ EXPORT_SYMBOL_GPL(__suspend_report_result);
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* @dev: Device to wait for.
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* @dev: Device to wait for.
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* @subordinate: Device that needs to wait for @dev.
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* @subordinate: Device that needs to wait for @dev.
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*/
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*/
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void device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
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int device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
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{
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{
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dpm_wait(dev, subordinate->power.async_suspend);
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dpm_wait(dev, subordinate->power.async_suspend);
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return async_error;
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}
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}
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EXPORT_SYMBOL_GPL(device_pm_wait_for_dev);
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EXPORT_SYMBOL_GPL(device_pm_wait_for_dev);
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@ -559,7 +559,7 @@ extern void __suspend_report_result(const char *function, void *fn, int ret);
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__suspend_report_result(__func__, fn, ret); \
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__suspend_report_result(__func__, fn, ret); \
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} while (0)
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} while (0)
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extern void device_pm_wait_for_dev(struct device *sub, struct device *dev);
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extern int device_pm_wait_for_dev(struct device *sub, struct device *dev);
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#else /* !CONFIG_PM_SLEEP */
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#else /* !CONFIG_PM_SLEEP */
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#define device_pm_lock() do {} while (0)
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#define device_pm_lock() do {} while (0)
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@ -572,7 +572,10 @@ static inline int dpm_suspend_start(pm_message_t state)
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#define suspend_report_result(fn, ret) do {} while (0)
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#define suspend_report_result(fn, ret) do {} while (0)
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static inline void device_pm_wait_for_dev(struct device *a, struct device *b) {}
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static inline int device_pm_wait_for_dev(struct device *a, struct device *b)
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{
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return 0;
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}
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#endif /* !CONFIG_PM_SLEEP */
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#endif /* !CONFIG_PM_SLEEP */
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/* How to reorder dpm_list after device_move() */
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/* How to reorder dpm_list after device_move() */
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