net: fec: don't transfer ownership until descriptor write is complete

If you don't own it, you shouldn't write to it.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index ca2708d13dfea9a0d0b58d3276d9e6b3f46d740a..97ca72a6aaf4b8035c192ce0c7700ec01d6ee7ce 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -390,6 +390,10 @@ fec_enet_txq_submit_frag_skb(struct fec_enet_priv_tx_q *txq,
 
                bdp->cbd_bufaddr = cpu_to_fec32(addr);
                bdp->cbd_datlen = cpu_to_fec16(frag_len);
+               /* Make sure the updates to rest of the descriptor are
+                * performed before transferring ownership.
+                */
+               wmb();
                bdp->cbd_sc = cpu_to_fec16(status);
        }
 
@@ -499,6 +503,10 @@ static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq,
 
        bdp->cbd_datlen = cpu_to_fec16(buflen);
        bdp->cbd_bufaddr = cpu_to_fec32(addr);
+       /* Make sure the updates to rest of the descriptor are performed before
+        * transferring ownership.
+        */
+       wmb();
 
        /* Send it on its way.  Tell FEC it's ready, interrupt when done,
         * it's the last BD of the frame, and to put the CRC on the end.
@@ -1475,7 +1483,6 @@ rx_processing_done:
 
                /* Mark the buffer empty */
                status |= BD_ENET_RX_EMPTY;
-               bdp->cbd_sc = cpu_to_fec16(status);
 
                if (fep->bufdesc_ex) {
                        struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
@@ -1484,6 +1491,11 @@ rx_processing_done:
                        ebdp->cbd_prot = 0;
                        ebdp->cbd_bdu = 0;
                }
+               /* Make sure the updates to rest of the descriptor are
+                * performed before transferring ownership.
+                */
+               wmb();
+               bdp->cbd_sc = cpu_to_fec16(status);
 
                /* Update BD pointer to next entry */
                bdp = fec_enet_get_nextdesc(bdp, &rxq->bd);