netdev - [RFC PATCH v3 net-next 3/3] tcp: Handle eor bit when fragmenting a skb

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Date:	Tue, 19 Apr 2016 23:24:57 -0700
From:	Martin KaFai Lau <kafai@...com>
To:	<netdev@...r.kernel.org>
CC:	Eric Dumazet <edumazet@...gle.com>,
	Neal Cardwell <ncardwell@...gle.com>,
	Soheil Hassas Yeganeh <soheil@...gle.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Yuchung Cheng <ycheng@...gle.com>,
	Kernel Team <kernel-team@...com>
Subject: [RFC PATCH v3 net-next 3/3] tcp: Handle eor bit when fragmenting a skb

When fragmenting a skb, the next_skb should carry
the eor from prev_skb.  The eor of prev_skb should
also be reset.

Signed-off-by: Martin KaFai Lau <kafai@...com>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Neal Cardwell <ncardwell@...gle.com>
Cc: Soheil Hassas Yeganeh <soheil@...gle.com>
Cc: Willem de Bruijn <willemb@...gle.com>
Cc: Yuchung Cheng <ycheng@...gle.com>
---
 net/ipv4/tcp_output.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 96bdf98..95f419b 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1128,6 +1128,12 @@ static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2)
 	}
 }
 
+static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2)
+{
+	TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor;
+	TCP_SKB_CB(skb)->eor = 0;
+}
+
 /* Function to create two new TCP segments.  Shrinks the given segment
  * to the specified size and appends a new segment with the rest of the
  * packet to the list.  This won't be called frequently, I hope.
@@ -1173,6 +1179,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
 	TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
 	TCP_SKB_CB(buff)->tcp_flags = flags;
 	TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked;
+	tcp_skb_fragment_eor(skb, buff);
 
 	if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) {
 		/* Copy and checksum data tail into the new buffer. */
@@ -1733,6 +1740,8 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
 	/* This packet was never sent out yet, so no SACK bits. */
 	TCP_SKB_CB(buff)->sacked = 0;
 
+	tcp_skb_fragment_eor(skb, buff);
+
 	buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL;
 	skb_split(skb, buff, len);
 	tcp_fragment_tstamp(skb, buff);
-- 
2.5.1