Reject new SCAN commands if there is a pending request

FAIL-BUSY was already returned for the case where a scan had been
started, but with the radio work design, it would have been possible to
schedule multiple scan requests if a non-scan radio work was in
progress. Multiple back-to-back scans are not usually very helpful, so
reject this type of cases where the SCAN command would be used to build
such a sequence.

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

wpa_supplicant/ctrl_iface.c

@@ -6286,6 +6286,13 @@ static void wpas_ctrl_scan(struct wpa_supplicant *wpa_s, char *params,
 		return;
 	}
 
+	if (radio_work_pending(wpa_s, "scan")) {
+		wpa_printf(MSG_DEBUG,
+			   "Pending scan scheduled - reject new request");
+		*reply_len = os_snprintf(reply, reply_size, "FAIL-BUSY\n");
+		return;
+	}
+
 	if (params) {
 		if (os_strncasecmp(params, "TYPE=ONLY", 9) == 0)
 			scan_only = 1;