mac80211: remove WARN_ON() from ieee80211_hw_config

ieee80211_hw_config can return an error when the hardware
has rfkill enabled. A WARN_ON() is too harsh for this
failure as it is a valid scenario. Only comment this warning
as we would like to have it back when rfkill is integrated into
mac80211.

Also reintroduce propagation of error if ieee80211_hw_config fails
in ieee80211_config_beacon.

This patch partially reverts patch:
5f0387fc3337ca26f0745f945f550f0c3734960f
"mac80211: clean up ieee80211_hw_config errors"
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/cfg.c

@@ -396,8 +396,10 @@ static int ieee80211_config_beacon(struct ieee80211_sub_if_data *sdata,
 	 */
 	if (params->interval) {
 		sdata->local->hw.conf.beacon_int = params->interval;
-		ieee80211_hw_config(sdata->local,
+		err = ieee80211_hw_config(sdata->local,
 					IEEE80211_CONF_CHANGE_BEACON_INTERVAL);
+		if (err < 0)
+			return err;
 		/*
 		 * We updated some parameter so if below bails out
 		 * it's not an error.

net/mac80211/main.c

@@ -243,10 +243,20 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 	if (changed && local->open_count) {
 		ret = local->ops->config(local_to_hw(local), changed);
 		/*
+		 * Goal:
 		 * HW reconfiguration should never fail, the driver has told
 		 * us what it can support so it should live up to that promise.
+		 *
+		 * Current status:
+		 * rfkill is not integrated with mac80211 and a
+		 * configuration command can thus fail if hardware rfkill
+		 * is enabled
+		 *
+		 * FIXME: integrate rfkill with mac80211 and then add this
+		 * WARN_ON() back
+		 *
 		 */
-		WARN_ON(ret);
+		/* WARN_ON(ret); */
 	}
 
 	return ret;