gro: prevent ACE field corruption & better AccECN handling

There are important differences in how the CWR field behaves
in RFC3168 and AccECN. With AccECN, CWR flag is part of the
ACE counter and its changes are important so adjust the flags
changed mask accordingly.

Also, if CWR is there, set the Accurate ECN GSO flag to avoid
corrupting CWR flag somewhere.

Signed-off-by: Ilpo Järvinen <ij@kernel.org>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 8c74fd69db2a8acc6e38d09ec81f1a741b83e540..934f777f29d36c8f73c508f95464d268d1c04096 100644 (file)
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -332,7 +332,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
        th2 = tcp_hdr(p);
        flush = (__force int)(flags & TCP_FLAG_CWR);
        flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
-                 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
+                 ~(TCP_FLAG_FIN | TCP_FLAG_PSH));
        flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
        for (i = sizeof(*th); i < thlen; i += 4)
                flush |= *(u32 *)((u8 *)th + i) ^
@@ -408,7 +408,7 @@ void tcp_gro_complete(struct sk_buff *skb)
        shinfo->gso_segs = NAPI_GRO_CB(skb)->count;
 
        if (th->cwr)
-               shinfo->gso_type |= SKB_GSO_TCP_ECN;
+               shinfo->gso_type |= SKB_GSO_TCP_ACCECN;
 }
 EXPORT_SYMBOL(tcp_gro_complete);