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tcp: Honor the eor bit in tcp_mtu_probe
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Avoid SKB coalescing if eor bit is set in one of the relevant
SKBs.

Fixes: c134ecb ("tcp: Make use of MSG_EOR in tcp_sendmsg")
Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Ilya Lesokhin authored and David S. Miller committed Feb 12, 2018
1 parent fb23403 commit 808cf9e
Showing 1 changed file with 25 additions and 0 deletions.
25 changes: 25 additions & 0 deletions net/ipv4/tcp_output.c
Original file line number Diff line number Diff line change
Expand Up @@ -2027,6 +2027,24 @@ static inline void tcp_mtu_check_reprobe(struct sock *sk)
}
}

static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len)
{
struct sk_buff *skb, *next;

skb = tcp_send_head(sk);
tcp_for_write_queue_from_safe(skb, next, sk) {
if (len <= skb->len)
break;

if (unlikely(TCP_SKB_CB(skb)->eor))
return false;

len -= skb->len;
}

return true;
}

/* Create a new MTU probe if we are ready.
* MTU probe is regularly attempting to increase the path MTU by
* deliberately sending larger packets. This discovers routing
Expand Down Expand Up @@ -2099,6 +2117,9 @@ static int tcp_mtu_probe(struct sock *sk)
return 0;
}

if (!tcp_can_coalesce_send_queue_head(sk, probe_size))
return -1;

/* We're allowed to probe. Build it now. */
nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false);
if (!nskb)
Expand Down Expand Up @@ -2134,6 +2155,10 @@ 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;
/* If this is the last SKB we copy and eor is set
* we need to propagate it to the new skb.
*/
TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor;
tcp_unlink_write_queue(skb, sk);
sk_wmem_free_skb(sk, skb);
} else {
Expand Down

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