Re: [PATCH net-next] ip_gre: remove CRC flag from dev features in gre_gso_segment
From: Jakub Kicinski <kuba@kernel.org>
Date: 2020-11-18 00:30:15
Also in:
linux-sctp
On Mon, 16 Nov 2020 17:15:47 +0800 Xin Long wrote:
This patch is to let it always do CRC checksum in sctp_gso_segment()
by removing CRC flag from the dev features in gre_gso_segment() for
SCTP over GRE, just as it does in Commit 527beb8ef9c0 ("udp: support
sctp over udp in skb_udp_tunnel_segment") for SCTP over UDP.
It could set csum/csum_start in GSO CB properly in sctp_gso_segment()
after that commit, so it would do checksum with gso_make_checksum()
in gre_gso_segment(), and Commit 622e32b7d4a6 ("net: gre: recompute
gre csum for sctp over gre tunnels") can be reverted now.
Signed-off-by: Xin Long <lucien.xin@gmail.com>Makes sense, but does GRE tunnels don't always have a csum. Is the current hardware not capable of generating CRC csums over encapsulated patches at all? I guess UDP tunnels can be configured without the csums as well so the situation isn't much different.
quoted hunk ↗ jump to hunk
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c index e0a2465..a5935d4 100644 --- a/net/ipv4/gre_offload.c +++ b/net/ipv4/gre_offload.c@@ -15,12 +15,12 @@ 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, need_recompute_csum, gso_partial; struct sk_buff *segs = ERR_PTR(-EINVAL); u16 mac_offset = skb->mac_header; __be16 protocol = skb->protocol; u16 mac_len = skb->mac_len; int gre_offset, outer_hlen; + bool need_csum, gso_partial;
Nit, rev xmas tree looks broken now.
quoted hunk ↗ jump to hunk
if (!skb->encapsulation) goto out;@@ -41,10 +41,10 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb, skb->protocol = skb->inner_protocol; need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM); - need_recompute_csum = skb->csum_not_inet; skb->encap_hdr_csum = need_csum; features &= skb->dev->hw_enc_features; + features &= ~NETIF_F_SCTP_CRC; /* segment inner packet. */ segs = skb_mac_gso_segment(skb, features);@@ -99,15 +99,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb, } *(pcsum + 1) = 0; - if (need_recompute_csum && !skb_is_gso(skb)) { - __wsum csum; - - csum = skb_checksum(skb, gre_offset, - skb->len - gre_offset, 0); - *pcsum = csum_fold(csum); - } else { - *pcsum = gso_make_checksum(skb, 0); - } + *pcsum = gso_make_checksum(skb, 0); } while ((skb = skb->next)); out: return segs;