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@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 0 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e9f985e42405..b2bca373f8be 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -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
@@ -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)
@@ -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 {