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>

diff --git a/drivers/bluetooth/btmrvl_main.c b/drivers/bluetooth/btmrvl_main.c
index 3a4343b..9a9f518 100644 (file)
--- a/drivers/bluetooth/btmrvl_main.c
+++ b/drivers/bluetooth/btmrvl_main.c
@@ -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;