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Bluetooth: btmrvl: fix thread stopping race

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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>
This commit is contained in:
Daniel Drake 2013-06-11 15:40:20 -04:00 committed by John W. Linville
parent 59f45d576a
commit ea05fea904
1 changed files with 4 additions and 5 deletions
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9
drivers/bluetooth/btmrvl_main.c
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@ -498,6 +498,10 @@ static int btmrvl_service_main_thread(void *data)
add_wait_queue(&thread->wait_q, &wait); add_wait_queue(&thread->wait_q, &wait);
set_current_state(TASK_INTERRUPTIBLE); set_current_state(TASK_INTERRUPTIBLE);
if (kthread_should_stop()) {
BT_DBG("main_thread: break from main thread");
break;
}
if (adapter->wakeup_tries || if (adapter->wakeup_tries ||
((!adapter->int_count) && ((!adapter->int_count) &&
@ -513,11 +517,6 @@ static int btmrvl_service_main_thread(void *data)
BT_DBG("main_thread woke up"); 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); spin_lock_irqsave(&priv->driver_lock, flags);
if (adapter->int_count) { if (adapter->int_count) {
adapter->int_count = 0; adapter->int_count = 0;