qcacld-3.0: Fix race condition between tx traffic and peer deletion

A race condition has been observed between outgoing TX traffic and
peer deletion when DUT has concurrent SAP(DBS) and STA sessions in 5G
and 2G respectively and the peer connected to SAP moves away triggering
peer deletion at DUT. Due to peer being deleted, the vdev corresponding
to the peer is void which results in a crash in ol_tx_data function
while trying to send Tx data.

Fix crash by checking for a null vdev in ol_tx_data.

CRs-Fixed: 1012681
Change-Id: Id0aab4b1f03ed24dfb55e09fa1a115edfdfcce84

core/dp/txrx/ol_tx.c

@@ -142,10 +142,18 @@ static inline uint8_t ol_tx_prepare_tso(ol_txrx_vdev_handle vdev,
 qdf_nbuf_t ol_tx_data(ol_txrx_vdev_handle vdev, qdf_nbuf_t skb)
 {
 	void *qdf_ctx = cds_get_context(QDF_MODULE_ID_QDF_DEVICE);
-	struct ol_txrx_pdev_t *pdev = vdev->pdev;
+	struct ol_txrx_pdev_t *pdev;
 	qdf_nbuf_t ret;
 	QDF_STATUS status;
 
+	if (qdf_unlikely(!vdev)) {
+		QDF_TRACE(QDF_MODULE_ID_TXRX, QDF_TRACE_LEVEL_WARN,
+			"%s:vdev is null", __func__);
+		return skb;
+	} else {
+		pdev = vdev->pdev;
+	}
+
 	if (qdf_unlikely(!pdev)) {
 		QDF_TRACE(QDF_MODULE_ID_TXRX, QDF_TRACE_LEVEL_WARN,
 			"%s:pdev is null", __func__);