Messages in this thread |  | | Subject | Re: [PATCH v10 54/55] Input: atmel_mxt_ts: Implement synchronization during various operation | From | "Wang, Jiada" <> | Date | Thu, 2 Apr 2020 20:50:09 +0900 |
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Hi Dmitry
On 2020/04/02 1:04, Dmitry Osipenko wrote: > 31.03.2020 13:50, Jiada Wang пишет: >> From: Sanjeev Chugh <sanjeev_chugh@mentor.com> >> >> 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
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