Subject: [PATCH 16/28] net: qualcomm: rmnet: Fix incorrect UL checksum offload logic

From: Subash Abhinov Kasiviswanathan <[email-masked]>
Date: Thu, 25 Jul 2019 12:07:12 -0600

[ Upstream commit a7cf3d24ee6081930feb4c830a7f6f16ebe31c49 ]

The udp_ip4_ind bit is set only for IPv4 UDP non-fragmented packets
so that the hardware can flip the checksum to 0xFFFF if the computed
checksum is 0 per RFC768.

However, this bit had to be set for IPv6 UDP non fragmented packets
as well per hardware requirements. Otherwise, IPv6 UDP packets
with computed checksum as 0 were transmitted by hardware and were
dropped in the network.

In addition to setting this bit for IPv6 UDP, the field is also
appropriately renamed to udp_ind as part of this change.

Fixes: 5eb5f8608ef1 ("net: qualcomm: rmnet: Add support for TX checksum offload")
Cc: Sean Tranchetti <[email-masked]>
Signed-off-by: Subash Abhinov Kasiviswanathan <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h     |  2 +-
 .../net/ethernet/qualcomm/rmnet/rmnet_map_data.c    | 13 +++++++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index 884f1f52dcc2..70879a3ab567 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
@@ -59,7 +59,7 @@ struct rmnet_map_dl_csum_trailer {
 struct rmnet_map_ul_csum_header {
 	__be16 csum_start_offset;
 	u16 csum_insert_offset:14;
-	u16 udp_ip4_ind:1;
+	u16 udp_ind:1;
 	u16 csum_enabled:1;
 } __aligned(1);
 
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 57a9c314a665..b2090cedd2e9 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -215,9 +215,9 @@ rmnet_map_ipv4_ul_csum_header(void *iphdr,
 	ul_header->csum_insert_offset = skb->csum_offset;
 	ul_header->csum_enabled = 1;
 	if (ip4h->protocol == IPPROTO_UDP)
-		ul_header->udp_ip4_ind = 1;
+		ul_header->udp_ind = 1;
 	else
-		ul_header->udp_ip4_ind = 0;
+		ul_header->udp_ind = 0;
 
 	/* Changing remaining fields to network order */
 	hdr++;
@@ -248,6 +248,7 @@ rmnet_map_ipv6_ul_csum_header(void *ip6hdr,
 			      struct rmnet_map_ul_csum_header *ul_header,
 			      struct sk_buff *skb)
 {
+	struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr;
 	__be16 *hdr = (__be16 *)ul_header, offset;
 
 	offset = htons((__force u16)(skb_transport_header(skb) -
@@ -255,7 +256,11 @@ rmnet_map_ipv6_ul_csum_header(void *ip6hdr,
 	ul_header->csum_start_offset = offset;
 	ul_header->csum_insert_offset = skb->csum_offset;
 	ul_header->csum_enabled = 1;
-	ul_header->udp_ip4_ind = 0;
+
+	if (ip6h->nexthdr == IPPROTO_UDP)
+		ul_header->udp_ind = 1;
+	else
+		ul_header->udp_ind = 0;
 
 	/* Changing remaining fields to network order */
 	hdr++;
@@ -428,7 +433,7 @@ void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 	ul_header->csum_start_offset = 0;
 	ul_header->csum_insert_offset = 0;
 	ul_header->csum_enabled = 0;
-	ul_header->udp_ip4_ind = 0;
+	ul_header->udp_ind = 0;
 
 	priv->stats.csum_sw++;
 }
-- 
2.20.1