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>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/net/wireless/b43/rfkill.c b/drivers/net/wireless/b43/rfkill.c
index 800e0a61a7f5..456930ffef2d 100644
--- 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);