ath5k: disable tasklets during reset

Based on a patch from Bruno Randolf, attempting useful
work while we are resetting the chip just leads to interface
lockups and bad descriptor data, and possibly DMAing to
freed buffers.  Let's suspend all tasklets while
reprogramming the registers in the card to avoid such
problems.

In the future we can convert the tasklets to threaded
interrupt handlers to simplify things.
Signed-off-by: NBob Copeland <me@bobcopeland.com>
Acked-by: NBruno Randolf <br1@einfach.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/base.c

@@ -2639,6 +2639,15 @@ ath5k_stop_locked(struct ath5k_softc *sc)
 	return 0;
 }
 
+static void stop_tasklets(struct ath5k_softc *sc)
+{
+	tasklet_kill(&sc->rxtq);
+	tasklet_kill(&sc->txtq);
+	tasklet_kill(&sc->calib);
+	tasklet_kill(&sc->beacontq);
+	tasklet_kill(&sc->ani_tasklet);
+}
+
 /*
  * Stop the device, grabbing the top-level lock to protect
  * against concurrent entry through ath5k_init (which can happen
@@ -2683,11 +2692,7 @@ ath5k_stop_hw(struct ath5k_softc *sc)
 	mmiowb();
 	mutex_unlock(&sc->lock);
 
-	tasklet_kill(&sc->rxtq);
-	tasklet_kill(&sc->txtq);
-	tasklet_kill(&sc->calib);
-	tasklet_kill(&sc->beacontq);
-	tasklet_kill(&sc->ani_tasklet);
+	stop_tasklets(sc);
 
 	ath5k_rfkill_hw_stop(sc->ah);
 
@@ -2937,8 +2942,11 @@ ath5k_reset(struct ath5k_softc *sc, struct ieee80211_channel *chan)
 
 	ATH5K_DBG(sc, ATH5K_DEBUG_RESET, "resetting\n");
 
+	ath5k_hw_set_imr(ah, 0);
+	synchronize_irq(sc->pdev->irq);
+	stop_tasklets(sc);
+
 	if (chan) {
-		ath5k_hw_set_imr(ah, 0);
 		ath5k_txq_cleanup(sc);
 		ath5k_rx_stop(sc);