diff options
| author |   Alex Elder <elder@linaro.org> | 2021-06-12 09:37:31 -0500 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2021-06-12 13:18:48 -0700 |
| commit | 9d0407bc4c9ca7a2378230dd86f8ce90a2b6ad09 (patch) | |
| tree | 61a9fd7fa2b1cab1eb3ff9a8aa38ce927d1f2d4e /drivers/net/ethernet/qualcomm/rmnet | |
| parent | net: qualcomm: rmnet: rearrange some NOTs (diff) | |
| download | linux-dev-9d0407bc4c9ca7a2378230dd86f8ce90a2b6ad09.tar.xz linux-dev-9d0407bc4c9ca7a2378230dd86f8ce90a2b6ad09.zip | |
net: qualcomm: rmnet: show that an intermediate sum is zero
This patch simply demonstrates that a checksum value computed when
verifying an offloaded transport checksum value for both IPv4 and
IPv6 is (normally) 0. It can be squashed into the next patch.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/qualcomm/rmnet')
| -rw-r--r-- | drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c index 1b170e9189d8..51909b8fa8a8 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c @@ -84,6 +84,11 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb, ip4h->protocol, 0); pseudo_csum = csum16_add(ip_payload_csum, (__force __be16)pseudo_csum); + /* The trailer checksum *includes* the checksum in the transport + * header. Adding that to the pseudo checksum will yield 0xffff + * ("negative 0") if the message arrived intact. + */ + WARN_ON((__sum16)~pseudo_csum); csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field); if (unlikely(!csum_value_final)) { @@ -150,6 +155,10 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, length, ip6h->nexthdr, 0); pseudo_csum = csum16_add(ip6_payload_csum, (__force __be16)pseudo_csum); + /* Adding the payload checksum to the pseudo checksum yields 0xffff + * ("negative 0") if the message arrived intact. + */ + WARN_ON((__sum16)~pseudo_csum); csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field); if (unlikely(csum_value_final == 0)) { |