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ip_gre: add csum offload support for gre header

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This patch is to add csum offload support for gre header:

On the TX path in gre_build_header(), when CHECKSUM_PARTIAL's set
for inner proto, it will calculate the csum for outer proto, and
inner csum will be offloaded later. Otherwise, CHECKSUM_PARTIAL
and csum_start/offset will be set for outer proto, and the outer
csum will be offloaded later.

On the GSO path in gre_gso_segment(), when CHECKSUM_PARTIAL is
not set for inner proto and the hardware supports csum offload,
CHECKSUM_PARTIAL and csum_start/offset will be set for outer
proto, and outer csum will be offloaded later. Otherwise, it
will do csum for outer proto by calling gso_make_checksum().

Note that SCTP has to do the csum by itself for non GSO path in
sctp_packet_pack(), as gre_build_header() can't handle the csum
with CHECKSUM_PARTIAL set for SCTP CRC csum offload.

v1->v2:
  - remove the SCTP part, as GRE dev doesn't support SCTP CRC CSUM
    and it will always do checksum for SCTP in sctp_packet_pack()
    when it's not a GSO packet.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Xin Long 2021-01-28 17:18:32 +08:00 committed by Jakub Kicinski
parent 62fafcd631
commit efa1a65c7e
2 changed files with 20 additions and 14 deletions
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19
include/net/gre.h
View File

@ -106,17 +106,6 @@ static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
return flags;
}
static inline __sum16 gre_checksum(struct sk_buff *skb)
{
__wsum csum;
if (skb->ip_summed == CHECKSUM_PARTIAL)
csum = lco_csum(skb);
else
csum = skb_checksum(skb, 0, skb->len, 0);
return csum_fold(csum);
}
static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
__be16 flags, __be16 proto,
__be32 key, __be32 seq)
@ -146,7 +135,13 @@ static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
!(skb_shinfo(skb)->gso_type &
(SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
*ptr = 0;
*(__sum16 *)ptr = gre_checksum(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL) {
*(__sum16 *)ptr = csum_fold(lco_csum(skb));
} else {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = sizeof(*greh);
}
}
}
}

13
net/ipv4/gre_offload.c
View File

@ -15,10 +15,10 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
bool need_csum, offload_csum, gso_partial, need_ipsec;
struct sk_buff *segs = ERR_PTR(-EINVAL);
u16 mac_offset = skb->mac_header;
__be16 protocol = skb->protocol;
bool need_csum, gso_partial;
u16 mac_len = skb->mac_len;
int gre_offset, outer_hlen;
@ -47,6 +47,11 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
if (need_csum)
features &= ~NETIF_F_SCTP_CRC;
need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
/* Try to offload checksum if possible */
offload_csum = !!(need_csum && !need_ipsec &&
(skb->dev->features & NETIF_F_HW_CSUM));
/* segment inner packet. */
segs = skb_mac_gso_segment(skb, features);
if (IS_ERR_OR_NULL(segs)) {
@ -100,7 +105,13 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
}
*(pcsum + 1) = 0;
if (skb->encapsulation || !offload_csum) {
*pcsum = gso_make_checksum(skb, 0);
} else {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = sizeof(*greh);
}
} while ((skb = skb->next));
out:
return segs;