From b75803d52a2ce1f6cbaf7ae0ae40a369210070cf Mon Sep 17 00:00:00 2001 From: Lawrence Brakmo Date: Fri, 6 May 2016 20:35:35 -0700 Subject: [PATCH] tcp: refactor struct tcp_skb_cb Refactor tcp_skb_cb to create two overlaping areas to store state for incoming or outgoing skbs based on comments by Neal Cardwell to tcp_nv patch: AFAICT this patch would not require an increase in the size of sk_buff cb[] if it were to take advantage of the fact that the tcp_skb_cb header.h4 and header.h6 fields are only used in the packet reception code path, and this in_flight field is only used on the transmit side. Signed-off-by: Lawrence Brakmo Acked-by: Yuchung Cheng Signed-off-by: David S. Miller --- include/net/tcp.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 24ec804..4775a1b 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -765,11 +765,16 @@ struct tcp_skb_cb { unused:6; __u32 ack_seq; /* Sequence number ACK'd */ union { - struct inet_skb_parm h4; + struct { + /* There is space for up to 20 bytes */ + } tx; /* only used for outgoing skbs */ + union { + struct inet_skb_parm h4; #if IS_ENABLED(CONFIG_IPV6) - struct inet6_skb_parm h6; + struct inet6_skb_parm h6; #endif - } header; /* For incoming frames */ + } header; /* For incoming skbs */ + }; }; #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) -- 2.7.4