ath5k: fix locking in ath5k_config

ath5k_config updates the software context without taking sc->lock.

Changes-licensed-under: 3-Clause-BSD
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath5k/base.c

@@ -1028,6 +1028,8 @@ ath5k_setup_bands(struct ieee80211_hw *hw)
  * it's done by reseting the chip.  To accomplish this we must
  * first cleanup any pending DMA, then restart stuff after a la
  * ath5k_init.
+ *
+ * Called with sc->lock.
  */
 static int
 ath5k_chan_set(struct ath5k_softc *sc, struct ieee80211_channel *chan)
@@ -2814,11 +2816,17 @@ ath5k_config(struct ieee80211_hw *hw, u32 changed)
 {
 	struct ath5k_softc *sc = hw->priv;
 	struct ieee80211_conf *conf = &hw->conf;
+	int ret;
+
+	mutex_lock(&sc->lock);
 
 	sc->bintval = conf->beacon_int;
 	sc->power_level = conf->power_level;
 
-	return ath5k_chan_set(sc, conf->channel);
+	ret = ath5k_chan_set(sc, conf->channel);
+
+	mutex_unlock(&sc->lock);
+	return ret;
 }
 
 static int