Re: [PATCH net] net: stmmac: fix stale descriptors and DMA mapping leak on Tx map failure

 	if (unlikely(is_jumbo)) {
-		entry = stmmac_jumbo_frm(priv, tx_q, skb, csum_insertion);
-		if (unlikely(entry < 0) && (entry != -EINVAL))
+		ret = stmmac_jumbo_frm(priv, tx_q, skb, csum_insertion);

+		if (unlikely(ret < 0) && (ret != -EINVAL))
 			goto dma_map_err;
+		entry = ret;
 	} else {
 		bool last_segment = (nfrags == 0);
 

@@ -4984,6 +4985,26 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 
 dma_map_err:
 	netdev_err(priv->dev, "Tx DMA map failed\n");
+
+	/* entry points one past the last descriptor written for this frame:
+	 * on failure it is the descriptor whose DMA mapping failed, so walk
+	 * from first_entry up to, but not including, entry.  Reset cur_tx
+	 * unconditionally as both stmmac_vlan_insert() and stmmac_jumbo_frm()
+	 * may have advanced it, and release the VLAN context descriptor.
+	 */
+	while (first_entry != entry) {
+		desc = stmmac_get_tx_desc(priv, tx_q, first_entry);
+		stmmac_release_tx_desc(priv, desc, priv->descriptor_mode);
+		stmmac_free_tx_buffer(priv, &priv->dma_conf, queue, first_entry);
+		first_entry = STMMAC_NEXT_ENTRY(first_entry,
+						priv->dma_conf.dma_tx_size);
+	}
+
+	tx_q->cur_tx = first_tx;