qcacmn: Fix duplicate additon of same WDI events to list

Same WDI subscribe event can be added multiple times to event list
since this is triggered by user control this will result to undefined
behaviour during events handling.

To avoid this add check to detect duplicate entry before adding
to list and reset list elements once removed from list.

Change-Id: Iaf23927f8439d4ac503776b915a8fe8cb6abfec5
CRs-Fixed: 2931068

dp/wifi3.0/dp_wdi_event.c

@@ -169,6 +169,7 @@ dp_wdi_event_sub(
 {
 	uint32_t event_index;
 	wdi_event_subscribe *wdi_sub;
+	wdi_event_subscribe *wdi_sub_itr;
 	struct dp_pdev *txrx_pdev =
 		dp_get_pdev_from_soc_pdev_id_wifi3((struct dp_soc *)soc,
 						   pdev_id);
@@ -205,6 +206,17 @@ dp_wdi_event_sub(
 		txrx_pdev->wdi_event_list[event_index] = wdi_sub;
 		return 0;
 	}
+
+	/* Check if event is already subscribed */
+	wdi_sub_itr = wdi_sub;
+	do {
+		if (wdi_sub_itr == event_cb_sub) {
+			QDF_TRACE(QDF_MODULE_ID_DP, QDF_TRACE_LEVEL_INFO,
+				  "Duplicate wdi subscribe event detected %s", __func__);
+			return 0;
+		}
+	} while ((wdi_sub_itr = dp_wdi_event_next_sub(wdi_sub_itr)));
+
 	event_cb_sub->priv.next = wdi_sub;
 	event_cb_sub->priv.prev = NULL;
 	wdi_sub->priv.prev = event_cb_sub;
@@ -253,6 +265,10 @@ dp_wdi_event_unsub(
 		event_cb_sub->priv.next->priv.prev = event_cb_sub->priv.prev;
 	}
 
+	/* Reset susbscribe event list elems */
+	event_cb_sub->priv.next = NULL;
+	event_cb_sub->priv.prev = NULL;
+
 	return 0;
 }