b43: Fix rfkill callback deadlock

wl->mutex might already be locked on initialization.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/b43/rfkill.c b/drivers/net/wireless/b43/rfkill.c
index 800e0a61a7f589f1f649b7f6417cf6488267f4d5..456930ffef2dc68ffa62814a60aa5fd8e947a07c 100644 (file)
--- a/drivers/net/wireless/b43/rfkill.c
+++ b/drivers/net/wireless/b43/rfkill.c
@@ -61,15 +61,22 @@ static void b43_rfkill_poll(struct input_polled_dev *poll_dev)
                mutex_unlock(&wl->mutex);
 }
 
-/* Called when the RFKILL toggled in software.
- * This is called without locking. */
+/* Called when the RFKILL toggled in software. */
 static int b43_rfkill_soft_toggle(void *data, enum rfkill_state state)
 {
        struct b43_wldev *dev = data;
        struct b43_wl *wl = dev->wl;
        int err = 0;
 
-       mutex_lock(&wl->mutex);
+       /* When RFKILL is registered, it will call back into this callback.
+        * wl->mutex will already be locked when this happens.
+        * So first trylock. On contention check if we are in initialization.
+        * Silently return if that happens to avoid a deadlock. */
+       if (mutex_trylock(&wl->mutex) == 0) {
+               if (b43_status(dev) < B43_STAT_INITIALIZED)
+                       return 0;
+               mutex_lock(&wl->mutex);
+       }
        if (b43_status(dev) < B43_STAT_INITIALIZED)
                goto out_unlock;
 
@@ -89,7 +96,6 @@ static int b43_rfkill_soft_toggle(void *data, enum rfkill_state state)
                        b43_radio_turn_off(dev, 0);
                break;
        }
-
 out_unlock:
        mutex_unlock(&wl->mutex);