On Fri 16 Dec 00:26 PST 2016, loic pallardy wrote: > > > On 12/16/2016 01:03 AM, Sarangdhar Joshi wrote: > >rproc_del() waits on firmware_loading_complete in order to > >make sure rproc_add() completed successfully before calling > >rproc_shutdown(). However since rproc_add() will always be > >called before rproc_del(), we do not need to wait on > >firmware_loading_complete. Drop this completion variable > >altogether. > > > Hi, > > firmware_loading_complete is used to synchronize all operations on rproc > with parallel work launched by request_firmware_nowait. We had a deadlock scenario in this code, where a call to rproc_boot() would grab the rproc mutex and the request_firmware_nowait() callback would wait on this lock before it would signal the completion that the rproc_boot() was waiting for. As the request_firmware_nowait() doesn't do anything other than handle auto_boot and signal the completion - and there is an internal sleep mechanism for handling concurrent request_firmware calls - I posted a patch and dropped the rproc_boot() wait thing. > rproc_add could be done and firmware loading still pending. In that case > rproc_del mustn't be called before end of the procedure. You're right. We might have an outstanding request_firmware_nowait() when we hit rproc_del() and we might free the underlaying rproc context. Holding a reference over the request_firmware_nowait() would solve this, but would cause issues if we get a rproc_add() from the same driver (e.g. after module unload/load) before the firmware timer has fired - and released the resources. This issue could be remedied by moving the rproc_delete_debug_dir() to rproc_del() and aim for not having any objects exposed outside the remoteproc core once rproc_del() returns. > > If you decide to remove this synchronization you need either to modify rproc > boot sequence or to replace it by something else. > I agree. Regards, Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
