diff options
| -rw-r--r-- | net/ipv4/tcp_output.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index ed750f9ceb0..01578f544ad 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1035,6 +1035,13 @@ static void tcp_cwnd_validate(struct sock *sk) * introducing MSS oddities to segment boundaries. In rare cases where * mss_now != mss_cache, we will request caller to create a small skb * per input skb which could be mostly avoided here (if desired). + * + * We explicitly want to create a request for splitting write queue tail + * to a small skb for Nagle purposes while avoiding unnecessary modulos, + * thus all the complexity (cwnd_len is always MSS multiple which we + * return whenever allowed by the other factors). Basically we need the + * modulo only when the receiver window alone is the limiting factor or + * when we would be allowed to send the split-due-to-Nagle skb fully. */ static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb, unsigned int mss_now, unsigned int cwnd) @@ -1048,10 +1055,11 @@ static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb, if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk))) return cwnd_len; - if (skb == tcp_write_queue_tail(sk) && cwnd_len <= skb->len) + needed = min(skb->len, window); + + if (skb == tcp_write_queue_tail(sk) && cwnd_len <= needed) return cwnd_len; - needed = min(skb->len, window); return needed - needed % mss_now; } |