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net: ethernet: ftgmac100: Fix DMA coherency issue with SW checksum 

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: 05690d633f ("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>
This commit is contained in:
Benjamin Herrenschmidt 2019-10-25 13:47:24 +11:00 committed by David S. Miller
parent 20eb4f29b6
commit 88824e3bf2
1 changed files with 12 additions and 13 deletions
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25
drivers/net/ethernet/faraday/ftgmac100.c
View File

@ -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);
@ -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 */