Merge branch 'stmmac-barrier-fixes-and-cleanup'

Niklas Cassel says:

====================
stmmac barrier fixes and cleanup
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c

@@ -389,6 +389,8 @@ static void dwmac4_rd_prepare_tso_tx_desc(struct dma_desc *p, int is_fs,
 
 static void dwmac4_release_tx_desc(struct dma_desc *p, int mode)
 {
+	p->des0 = 0;
+	p->des1 = 0;
 	p->des2 = 0;
 	p->des3 = 0;
 }

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1844,6 +1844,11 @@ static void stmmac_tx_clean(struct stmmac_priv *priv, u32 queue)
 		if (unlikely(status & tx_dma_own))
 			break;
 
+		/* Make sure descriptor fields are read after reading
+		 * the own bit.
+		 */
+		dma_rmb();
+
 		/* Just consider the last segment and ...*/
 		if (likely(!(status & tx_not_ls))) {
 			/* ... verify the status error condition */
@@ -2983,14 +2988,21 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 			tcp_hdrlen(skb) / 4, (skb->len - proto_hdr_len));
 
 	/* If context desc is used to change MSS */
-	if (mss_desc)
+	if (mss_desc) {
+		/* Make sure that first descriptor has been completely
+		 * written, including its own bit. This is because MSS is
+		 * actually before first descriptor, so we need to make
+		 * sure that MSS's own bit is the last thing written.
+		 */
+		dma_wmb();
 		priv->hw->desc->set_tx_owner(mss_desc);
+	}
 
 	/* The own bit must be the latest setting done when prepare the
 	 * descriptor and then barrier is needed to make sure that
 	 * all is coherent before granting the DMA engine.
 	 */
-	dma_wmb();
+	wmb();
 
 	if (netif_msg_pktdata(priv)) {
 		pr_info("%s: curr=%d dirty=%d f=%d, e=%d, f_p=%p, nfrags %d\n",
@@ -3214,7 +3226,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 		 * descriptor and then barrier is needed to make sure that
 		 * all is coherent before granting the DMA engine.
 		 */
-		dma_wmb();
+		wmb();
 	}
 
 	netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len);