From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 25 Oct 2019 13:47:24 +1100
Subject: net: ethernet: ftgmac100: Fix DMA coherency issue with SW checksum
Git-commit: 88824e3bf29a2fcacfd9ebbfe03063649f0f3254
Patch-mainline: 5.4-rc6
References: networking-stable-19_11_05
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: 05690d633f30 ("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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/net/ethernet/faraday/ftgmac100.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -734,6 +734,18 @@ static int ftgmac100_hard_start_xmit(str
*/
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);
@@ -760,19 +772,6 @@ static int ftgmac100_hard_start_xmit(str
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 */