netdev - [PATCH v2 1/1] tcp: Honor the eor bit in tcp_mtu

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Message-Id: <20180205181832.95136-1-ilyal@mellanox.com>
Date:   Mon,  5 Feb 2018 20:18:32 +0200
From:   Ilya Lesokhin <ilyal@...lanox.com>
To:     netdev@...r.kernel.org, eric.dumazet@...il.com, kafai@...com
Cc:     borisp@...lanox.com, Ilya Lesokhin <ilyal@...lanox.com>
Subject: [PATCH v2 1/1] tcp: Honor the eor bit in tcp_mtu_probe

Avoid SKB coalescing if eor bit is set in one of the relevant
SKBs.

Fixes: c134ecb87817 ("tcp: Make use of MSG_EOR in tcp_sendmsg")
Signed-off-by: Ilya Lesokhin <ilyal@...lanox.com>
---
 net/ipv4/tcp_output.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e9f985e42405..70c5bb4958c3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2099,6 +2099,17 @@ static int tcp_mtu_probe(struct sock *sk)
 			return 0;
 	}
 
+	len = probe_size;
+	tcp_for_write_queue_from_safe(skb, next, sk) {
+		if (len <= skb->len)
+			break;
+
+		if (unlikely(TCP_SKB_CB(skb)->eor))
+			return -1;
+
+		len -= skb->len;
+	}
+
 	/* We're allowed to probe.  Build it now. */
 	nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false);
 	if (!nskb)
@@ -2134,6 +2145,7 @@ static int tcp_mtu_probe(struct sock *sk)
 			/* We've eaten all the data from this skb.
 			 * Throw it away. */
 			TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags;
+			TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor;
 			tcp_unlink_write_queue(skb, sk);
 			sk_wmem_free_skb(sk, skb);
 		} else {
-- 
2.15.0.317.g14c63a9