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authorBen Hutchings <ben.hutchings@codethink.co.uk>2015-03-03 01:52:00 +0100
committerDavid S. Miller <davem@davemloft.net>2015-03-03 03:30:56 +0100
commit7d7355f58ba4f9d68d2fb79864bab4ccb618e4e1 (patch)
tree79a7efdc9a433f1c5f05651adc70c2579760c313 /drivers/net
parentMerge branch 'mlx4' (diff)
downloadlinux-7d7355f58ba4f9d68d2fb79864bab4ccb618e4e1.tar.xz
linux-7d7355f58ba4f9d68d2fb79864bab4ccb618e4e1.zip
sh_eth: Ensure proper ordering of descriptor active bit write/read
When submitting a DMA descriptor, the active bit must be written last. When reading a completed DMA descriptor, the active bit must be read first. Add memory barriers to ensure that this ordering is maintained. Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/renesas/sh_eth.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 654b48d1e61a..5c212a833bcf 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1410,6 +1410,8 @@ static int sh_eth_txfree(struct net_device *ndev)
txdesc = &mdp->tx_ring[entry];
if (txdesc->status & cpu_to_edmac(mdp, TD_TACT))
break;
+ /* TACT bit must be checked before all the following reads */
+ rmb();
/* Free the original skb. */
if (mdp->tx_skbuff[entry]) {
dma_unmap_single(&ndev->dev, txdesc->addr,
@@ -1447,6 +1449,8 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
limit = boguscnt;
rxdesc = &mdp->rx_ring[entry];
while (!(rxdesc->status & cpu_to_edmac(mdp, RD_RACT))) {
+ /* RACT bit must be checked before all the following reads */
+ rmb();
desc_status = edmac_to_cpu(mdp, rxdesc->status);
pkt_len = rxdesc->frame_length;
@@ -1526,6 +1530,7 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
skb_checksum_none_assert(skb);
rxdesc->addr = dma_addr;
}
+ wmb(); /* RACT bit must be set after all the above writes */
if (entry >= mdp->num_rx_ring - 1)
rxdesc->status |=
cpu_to_edmac(mdp, RD_RACT | RD_RFP | RD_RDEL);
@@ -2195,6 +2200,7 @@ static int sh_eth_start_xmit(struct sk_buff *skb, struct net_device *ndev)
}
txdesc->buffer_length = skb->len;
+ wmb(); /* TACT bit must be set after all the above writes */
if (entry >= mdp->num_tx_ring - 1)
txdesc->status |= cpu_to_edmac(mdp, TD_TACT | TD_TDLE);
else