b43: Fix controller restart crash

This fixes a kernel crash on rmmod, in the case where the controller
was restarted before doing the rmmod.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/main.c

@@ -4271,7 +4271,9 @@ static void b43_chip_reset(struct work_struct *work)
 			goto out;
 		}
 	}
-      out:
+out:
+	if (err)
+		wl->current_dev = NULL; /* Failed to init the dev. */
 	mutex_unlock(&wl->mutex);
 	if (err)
 		b43err(wl, "Controller restart FAILED\n");
@@ -4412,9 +4414,11 @@ static void b43_one_core_detach(struct ssb_device *dev)
 	struct b43_wldev *wldev;
 	struct b43_wl *wl;
 
+	/* Do not cancel ieee80211-workqueue based work here.
+	 * See comment in b43_remove(). */
+
 	wldev = ssb_get_drvdata(dev);
 	wl = wldev->wl;
-	cancel_work_sync(&wldev->restart_work);
 	b43_debugfs_remove_device(wldev);
 	b43_wireless_core_detach(wldev);
 	list_del(&wldev->list);
@@ -4599,6 +4603,10 @@ static void b43_remove(struct ssb_device *dev)
 	struct b43_wl *wl = ssb_get_devtypedata(dev);
 	struct b43_wldev *wldev = ssb_get_drvdata(dev);
 
+	/* We must cancel any work here before unregistering from ieee80211,
+	 * as the ieee80211 unreg will destroy the workqueue. */
+	cancel_work_sync(&wldev->restart_work);
+
 	B43_WARN_ON(!wl);
 	if (wl->current_dev == wldev)
 		ieee80211_unregister_hw(wl->hw);