mac80211: only transition STAs ps->wake on data frames

When a station goes to PS mode to scan, it will then send
probe requests without the PS bit set. mac80211 will take
that as indication that the station woke up, but it didn't.
This patch changes mac80211 to only consider doze->wake
transitions on data frames to to fix that issue.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Jouni Malinen <j@w1.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/rx.c

@@ -741,18 +741,30 @@ ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
 	sta->last_qual = rx->status->qual;
 	sta->last_noise = rx->status->noise;
 
+	/*
+	 * Change STA power saving mode only at the end of a frame
+	 * exchange sequence.
+	 */
 	if (!ieee80211_has_morefrags(hdr->frame_control) &&
 	    (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
 	     rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)) {
-		/* Change STA power saving mode only in the end of a frame
-		 * exchange sequence */
-		if (test_sta_flags(sta, WLAN_STA_PS) &&
+		if (test_sta_flags(sta, WLAN_STA_PS)) {
+			/*
+			 * Ignore doze->wake transitions that are
+			 * indicated by non-data frames, the standard
+			 * is unclear here, but for example going to
+			 * PS mode and then scanning would cause a
+			 * doze->wake transition for the probe request,
+			 * and that is clearly undesirable.
+			 */
+			if (ieee80211_is_data(hdr->frame_control) &&
 			    !ieee80211_has_pm(hdr->frame_control))
 				rx->sent_ps_buffered += ap_sta_ps_end(sta);
-		else if (!test_sta_flags(sta, WLAN_STA_PS) &&
-			 ieee80211_has_pm(hdr->frame_control))
+		} else {
+			if (ieee80211_has_pm(hdr->frame_control))
 				ap_sta_ps_start(sta);
 		}
+	}
 
 	/* Drop data::nullfunc frames silently, since they are used only to
 	 * control station power saving mode. */