Commit ea05fea9 authored Jun 11, 2013 by Daniel Drake Committed by John W. Linville Jun 13, 2013

Bluetooth: btmrvl: fix thread stopping race



There is currently a race condition in the btmrvl_remove_card() which
is causing hangs on suspend for OLPC. When the race occurs,
kthread_stop() never returns.

The problem is that btmrvl_service_main_thread() calls kthread_should_stop()
and then does a fair number of things before restarting the loop and
sleeping.

If the thread gets stopped after kthread_should_stop() is checked, but
before the sleep happens, the thread will go to sleep and won't necessarily
be woken up.

Move the kthread_should_stop() check into a race-free place.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

parent 59f45d57

drivers/bluetooth/btmrvl_main.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -498,6 +498,10 @@ static int btmrvl_service_main_thread(void *data)
		add_wait_queue(&thread->wait_q, &wait);

		set_current_state(TASK_INTERRUPTIBLE);
		if (kthread_should_stop()) {
		BT_DBG("main_thread: break from main thread");
		break;
		}

		if (adapter->wakeup_tries \|\|
		((!adapter->int_count) &&
		@@ -513,11 +517,6 @@ static int btmrvl_service_main_thread(void *data)

		BT_DBG("main_thread woke up");

		if (kthread_should_stop()) {
		BT_DBG("main_thread: break from main thread");
		break;
		}

		spin_lock_irqsave(&priv->driver_lock, flags);
		if (adapter->int_count) {
		adapter->int_count = 0;