path: root/net/ipv4/tcp_output.c
diff options
authorEric Dumazet <edumazet@google.com>2019-12-12 12:55:30 -0800
committerJakub Kicinski <jakub.kicinski@netronome.com>2019-12-13 21:58:40 -0800
commitee2aabd3fc2eef4c1a0ebdadccc76fbff74b94fc (patch)
treeff49c797d50165533687b248d7531010a9b24339 /net/ipv4/tcp_output.c
parenttcp: do not send empty skb from tcp_write_xmit() (diff)
tcp: refine tcp_write_queue_empty() implementation
Due to how tcp_sendmsg() is implemented, we can have an empty skb at the tail of the write queue. Most [1] tcp_write_queue_empty() callers want to know if there is anything to send (payload and/or FIN) Instead of checking if the sk_write_queue is empty, we need to test if tp->write_seq == tp->snd_nxt [1] tcp_send_fin() was the only caller that expected to see if an skb was in the write queue, I have changed the code to reuse the tcp_write_queue_tail() result. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Diffstat (limited to '')
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 57f434a8e41f..36902d08473e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3129,7 +3129,7 @@ void sk_forced_mem_schedule(struct sock *sk, int size)
void tcp_send_fin(struct sock *sk)
- struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk);
+ struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk);
struct tcp_sock *tp = tcp_sk(sk);
/* Optimization, tack on the FIN if we have one skb in write queue and
@@ -3137,6 +3137,7 @@ void tcp_send_fin(struct sock *sk)
* Note: in the latter case, FIN packet will be sent after a timeout,
* as TCP stack thinks it has already been transmitted.
+ tskb = tail;
if (!tskb && tcp_under_memory_pressure(sk))
tskb = skb_rb_last(&sk->tcp_rtx_queue);
@@ -3144,7 +3145,7 @@ void tcp_send_fin(struct sock *sk)
TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN;
- if (tcp_write_queue_empty(sk)) {
+ if (!tail) {
/* This means tskb was already sent.
* Pretend we included the FIN on previous transmit.
* We need to set tp->snd_nxt to the value it would have