On Thu, Mar 7, 2013 at 9:53 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > hotkey_kthread() does try_to_freeze() under hotkey_thread_mutex. > > We can simply kill this mutex, hotkey_poll_stop_sync() does not need > to serialize with hotkey_kthread(). When kthread_stop() returns the > thread is already dead, it called do_exit()->complete_vfork_done(). > > Reported-by: Artem Savkov <artem.savkov@xxxxxxxxx> > Reported-by: Maciej Rutecki <maciej.rutecki@xxxxxxxxx> > Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> > Reviewed-by: Mandeep Singh Baines <msb@xxxxxxxxxxxx> > --- x/drivers/platform/x86/thinkpad_acpi.c > +++ x/drivers/platform/x86/thinkpad_acpi.c > @@ -1965,9 +1965,6 @@ struct tp_nvram_state { > /* kthread for the hotkey poller */ > static struct task_struct *tpacpi_hotkey_task; > > -/* Acquired while the poller kthread is running, use to sync start/stop */ > -static struct mutex hotkey_thread_mutex; > - > /* > * Acquire mutex to write poller control variables as an > * atomic block. > @@ -2463,8 +2460,6 @@ static int hotkey_kthread(void *data) > unsigned int poll_freq; > bool was_frozen; > > - mutex_lock(&hotkey_thread_mutex); > - > if (tpacpi_lifecycle == TPACPI_LIFE_EXITING) > goto exit; > > @@ -2524,7 +2519,6 @@ static int hotkey_kthread(void *data) > } > > exit: > - mutex_unlock(&hotkey_thread_mutex); > return 0; > } > > @@ -2534,9 +2528,6 @@ static void hotkey_poll_stop_sync(void) > if (tpacpi_hotkey_task) { > kthread_stop(tpacpi_hotkey_task); > tpacpi_hotkey_task = NULL; > - mutex_lock(&hotkey_thread_mutex); > - /* at this point, the thread did exit */ > - mutex_unlock(&hotkey_thread_mutex); > } > } > > @@ -3235,7 +3226,6 @@ static int __init hotkey_init(struct ibm > mutex_init(&hotkey_mutex); > > #ifdef CONFIG_THINKPAD_ACPI_HOTKEY_POLL > - mutex_init(&hotkey_thread_mutex); > mutex_init(&hotkey_thread_data_mutex); > #endif > > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html