Skip to content

Commit

Permalink
net: ethernet: ftgmac100: Fix DMA coherency issue with SW checksum
Browse files Browse the repository at this point in the history
We are calling the checksum helper after the dma_map_single()
call to map the packet. This is incorrect as the checksumming
code will touch the packet from the CPU. This means the cache
won't be properly flushes (or the bounce buffering will leave
us with the unmodified packet to DMA).

This moves the calculation of the checksum & vlan tags to
before the DMA mapping.

This also has the side effect of fixing another bug: If the
checksum helper fails, we goto "drop" to drop the packet, which
will not unmap the DMA mapping.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Fixes: 05690d6 ("ftgmac100: Upgrade to NETIF_F_HW_CSUM")
Reviewed-by: Vijay Khemka <vijaykhemka@fb.com>
Tested-by: Vijay Khemka <vijaykhemka@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
Benjamin Herrenschmidt authored and David S. Miller committed Oct 28, 2019
1 parent 20eb4f2 commit 88824e3
Showing 1 changed file with 12 additions and 13 deletions.
25 changes: 12 additions & 13 deletions drivers/net/ethernet/faraday/ftgmac100.c
Original file line number Diff line number Diff line change
Expand Up @@ -727,6 +727,18 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
*/
nfrags = skb_shinfo(skb)->nr_frags;

/* Setup HW checksumming */
csum_vlan = 0;
if (skb->ip_summed == CHECKSUM_PARTIAL &&
!ftgmac100_prep_tx_csum(skb, &csum_vlan))
goto drop;

/* Add VLAN tag */
if (skb_vlan_tag_present(skb)) {
csum_vlan |= FTGMAC100_TXDES1_INS_VLANTAG;
csum_vlan |= skb_vlan_tag_get(skb) & 0xffff;
}

/* Get header len */
len = skb_headlen(skb);

Expand All @@ -753,19 +765,6 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
if (nfrags == 0)
f_ctl_stat |= FTGMAC100_TXDES0_LTS;
txdes->txdes3 = cpu_to_le32(map);

/* Setup HW checksumming */
csum_vlan = 0;
if (skb->ip_summed == CHECKSUM_PARTIAL &&
!ftgmac100_prep_tx_csum(skb, &csum_vlan))
goto drop;

/* Add VLAN tag */
if (skb_vlan_tag_present(skb)) {
csum_vlan |= FTGMAC100_TXDES1_INS_VLANTAG;
csum_vlan |= skb_vlan_tag_get(skb) & 0xffff;
}

txdes->txdes1 = cpu_to_le32(csum_vlan);

/* Next descriptor */
Expand Down

0 comments on commit 88824e3

Please sign in to comment.