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>
--- 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
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