Retry scan-for-connect if driver trigger fails

This restores some of the pre-radio work behavior for scanning by
retrying scan trigger if the driver rejects it (most likely returning
EBUSY in case of nl80211-drivers). Retry is indicated in the
CTRL-EVENT-SCAN-FAILED event with "retry=1".

For manual scans (e.g., triggered through "SCAN" control interface
command), no additional retries are performed. In other words, if upper
layers want to retry, they can do so based on the CTRL-EVENT-SCAN-FAILED
event.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/scan.c

@@ -177,11 +177,25 @@ static void wpas_trigger_scan_cb(struct wpa_radio_work *work, int deinit)
 	wpa_scan_free_params(params);
 	work->ctx = NULL;
 	if (ret) {
+		int retry = wpa_s->last_scan_req != MANUAL_SCAN_REQ;
+
+		if (wpa_s->disconnected)
+			retry = 0;
+
 		wpa_supplicant_notify_scanning(wpa_s, 0);
 		wpas_notify_scan_done(wpa_s, 0);
-		wpa_msg_ctrl(wpa_s, MSG_INFO, WPA_EVENT_SCAN_FAILED "ret=%d",
-			     ret);
+		if (wpa_s->wpa_state == WPA_SCANNING)
+			wpa_supplicant_set_state(wpa_s,
+						 wpa_s->scan_prev_wpa_state);
+		wpa_msg(wpa_s, MSG_INFO, WPA_EVENT_SCAN_FAILED "ret=%d%s",
+			ret, retry ? " retry=1" : "");
 		radio_work_done(work);
+
+		if (retry) {
+			/* Restore scan_req since we will try to scan again */
+			wpa_s->scan_req = wpa_s->last_scan_req;
+			wpa_supplicant_req_scan(wpa_s, 1, 0);
+		}
 		return;
 	}
 
@@ -613,7 +627,6 @@ static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 	struct wpa_driver_scan_params params;
 	struct wpa_driver_scan_params *scan_params;
 	size_t max_ssids;
-	enum wpa_states prev_state;
 
 	if (wpa_s->pno || wpa_s->pno_sched_pending) {
 		wpa_dbg(wpa_s, MSG_DEBUG, "Skip scan - PNO is in progress");
@@ -681,7 +694,7 @@ static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 
 	os_memset(&params, 0, sizeof(params));
 
-	prev_state = wpa_s->wpa_state;
+	wpa_s->scan_prev_wpa_state = wpa_s->wpa_state;
 	if (wpa_s->wpa_state == WPA_DISCONNECTED ||
 	    wpa_s->wpa_state == WPA_INACTIVE)
 		wpa_supplicant_set_state(wpa_s, WPA_SCANNING);
@@ -1001,8 +1014,9 @@ scan:
 
 	if (ret) {
 		wpa_msg(wpa_s, MSG_WARNING, "Failed to initiate AP scan");
-		if (prev_state != wpa_s->wpa_state)
-			wpa_supplicant_set_state(wpa_s, prev_state);
+		if (wpa_s->scan_prev_wpa_state != wpa_s->wpa_state)
+			wpa_supplicant_set_state(wpa_s,
+						 wpa_s->scan_prev_wpa_state);
 		/* Restore scan_req since we will try to scan again */
 		wpa_s->scan_req = wpa_s->last_scan_req;
 		wpa_supplicant_req_scan(wpa_s, 1, 0);

wpa_supplicant/wpa_supplicant_i.h

@@ -585,6 +585,7 @@ struct wpa_supplicant {
 		 */
 		MANUAL_SCAN_REQ
 	} scan_req, last_scan_req;
+	enum wpa_states scan_prev_wpa_state;
 	struct os_reltime scan_trigger_time, scan_start_time;
 	int scan_runs; /* number of scan runs since WPS was started */
 	int *next_scan_freqs;