> It looks like your patch runs into dead locks problems: > > I have a cron job reading my sensors. If I read the sensors on another > thread (e.g. via cat), the 2nd thread can produce a dead lock: > > * thread 1 has bus & sl lock > * thread 1 drops bus lock, keeps sl locks and sleeps > * thread 2 get bus lock, waits for sl lock > * thread 1 returns from sleep, waits for bus lock, but this is help by thread > 2
Aquiring sl lock before the bus lock prevents this dead lock (no change of locking-order). With search enabled, removing a device by w1_search_process_cb then also worked as intended: Mar 10 01:29:04 pi kernel: [ 924.870893] w1_therm_remove_slave about to lock faily_data->lock Mar 10 01:29:04 pi kernel: [ 924.870935] w1_therm_remove_slave unlocked faily_data->lock Mar 10 01:29:04 pi kernel: [ 924.871115] w1_therm_remove_slave about to lock faily_data->lock Mar 10 01:29:05 pi kernel: [ 925.151242] start sleep d117a600 refcnt 1 ** Mar 10 01:29:05 pi kernel: [ 925.151277] end sleep d117a600 refcnt 0 ** Mar 10 01:29:11 pi kernel: [ 931.295344] w1_slave_driver 10-000802cc045a: Read failed CRC check Mar 10 01:29:11 pi kernel: [ 931.295437] w1_therm_remove_slave unlocked faily_data->lock ** I get the ref-cnt before and after the sleep and only log if they differ. But I am unable to judge if mobing the sl lock at the beginning of w1_slave_show can cause dead locks in other scenarios. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
