cfg80211: Fix power save state after interface type change

Currently cfg80211 only configures the PSM state to the driver upon creation
of a new virtual interface, but not after interface type change. The mac80211
on the other hand reinitializes its sdata structure every time the interface
type is changed, losing the PSM configuration.

Hence, if the interface type is changed to, say, ad-hoc and then back to
managed, "iw wlan0 get power_save" will claim that PSM is enabled, when in
fact on mac80211 level it is not.

Fix this in cfg80211 by configuring the PSM state to the driver each time
the interface is brought up instead of just when the interface is created.
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/core.c

@@ -718,13 +718,6 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
 			wdev->ps = false;
 		/* allow mac80211 to determine the timeout */
 		wdev->ps_timeout = -1;
-		if (rdev->ops->set_power_mgmt)
-			if (rdev->ops->set_power_mgmt(wdev->wiphy, dev,
-						      wdev->ps,
-						      wdev->ps_timeout)) {
-				/* assume this means it's off */
-				wdev->ps = false;
-			}
 
 		if (!dev->ethtool_ops)
 			dev->ethtool_ops = &cfg80211_ethtool_ops;
@@ -813,6 +806,19 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
 		rdev->opencount++;
 		mutex_unlock(&rdev->devlist_mtx);
 		cfg80211_unlock_rdev(rdev);
+
+		/*
+		 * Configure power management to the driver here so that its
+		 * correctly set also after interface type changes etc.
+		 */
+		if (wdev->iftype == NL80211_IFTYPE_STATION &&
+		    rdev->ops->set_power_mgmt)
+			if (rdev->ops->set_power_mgmt(wdev->wiphy, dev,
+						      wdev->ps,
+						      wdev->ps_timeout)) {
+				/* assume this means it's off */
+				wdev->ps = false;
+			}
 		break;
 	case NETDEV_UNREGISTER:
 		/*