Hi Dmitry On 2020/04/02 1:04, Dmitry Osipenko wrote:
31.03.2020 13:50, Jiada Wang пишет:From: Sanjeev Chugh <sanjeev_chugh@xxxxxxxxxx> There could be scope of race conditions when sysfs is being handled and at the same time, device removal is occurring. For example, we don't want the device removal to begin if the Atmel device cfg update is going on or firmware update is going on. In such cases, wait for device update to be completed before the removal continues. Thread Thread 2: ========================= ========================= mxt_update_fw_store() mxt_remove() mutex_lock(&data->lock) ... mxt_initialize() //Tries to acquire lock request_firmware_nowait() mutex_lock(&data->lock) ... ==>waits for lock() ... . ... . mutex_unlock(&data->lock) . //Gets lock and proceeds mxt_free_input_device(); ... mutex_unlock(&data->lock) //Frees atmel driver data kfree(data) If the request_firmware_nowait() completes after the driver removal, and callback is triggered. But kernel crashes since the module is already removed. This commit adds state machine to serialize such scenarios.Won't it be easier to bump driver's module use-count by __module_get() while firmware is updating? Or remove sysfs during of mxt_remove()? >
thanks for your inspiration, I will replace state machine with module use-count.
Thanks, Jiada
