pm_send_all — send request to all managed devices


int pm_send_all (pm_request_t rqst, void * data);



power management request


data for the callback


Issue a power management request to a all devices. The PM_SUSPEND events are handled specially. Any device is permitted to fail a suspend by returning a non zero (error) value from its callback function. If any device vetoes a suspend request then all other devices that have suspended during the processing of this request are restored to their previous state.


This function takes the pm_devs_lock. The lock is not dropped until the callbacks have completed. This prevents races against pm locking functions, races against module unload pm_unregister code. It does mean however that you must not issue pm_ functions within the callback or you will deadlock and users will hate you.

Zero is returned on success. If a suspend fails then the status from the device that vetoes the suspend is returned.


what stops two power management requests occurring in parallel and conflicting.