[TCP]: skb pcount with MTU discovery
The problem is that when doing MTU discovery, the too-large segments in
the write queue will be calculated as having a pcount of >1. When
tcp_write_xmit() is trying to send, tcp_snd_test() fails the cwnd test
when pcount > cwnd.
The segments are eventually transmitted one at a time by keepalive, but
this can take a long time.
This patch checks if TSO is enabled when setting pcount.
Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 503810a..9355ae5 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1417,19 +1417,20 @@
tcp_minshall_check(tp))));
}
-extern void tcp_set_skb_tso_segs(struct sk_buff *, unsigned int);
+extern void tcp_set_skb_tso_segs(struct sock *, struct sk_buff *);
/* This checks if the data bearing packet SKB (usually sk->sk_send_head)
* should be put on the wire right now.
*/
-static __inline__ int tcp_snd_test(const struct tcp_sock *tp,
+static __inline__ int tcp_snd_test(struct sock *sk,
struct sk_buff *skb,
unsigned cur_mss, int nonagle)
{
+ struct tcp_sock *tp = tcp_sk(sk);
int pkts = tcp_skb_pcount(skb);
if (!pkts) {
- tcp_set_skb_tso_segs(skb, tp->mss_cache_std);
+ tcp_set_skb_tso_segs(sk, skb);
pkts = tcp_skb_pcount(skb);
}
@@ -1490,7 +1491,7 @@
if (skb) {
if (!tcp_skb_is_last(sk, skb))
nonagle = TCP_NAGLE_PUSH;
- if (!tcp_snd_test(tp, skb, cur_mss, nonagle) ||
+ if (!tcp_snd_test(sk, skb, cur_mss, nonagle) ||
tcp_write_xmit(sk, nonagle))
tcp_check_probe_timer(sk, tp);
}
@@ -1508,7 +1509,7 @@
struct sk_buff *skb = sk->sk_send_head;
return (skb &&
- tcp_snd_test(tp, skb, tcp_current_mss(sk, 1),
+ tcp_snd_test(sk, skb, tcp_current_mss(sk, 1),
tcp_skb_is_last(sk, skb) ? TCP_NAGLE_PUSH : tp->nonagle));
}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 13c14cb..a12df69 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -427,7 +427,7 @@
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb = sk->sk_send_head;
- if (tcp_snd_test(tp, skb, cur_mss, TCP_NAGLE_PUSH)) {
+ if (tcp_snd_test(sk, skb, cur_mss, TCP_NAGLE_PUSH)) {
/* Send it out now. */
TCP_SKB_CB(skb)->when = tcp_time_stamp;
tcp_tso_set_push(skb);
@@ -440,9 +440,12 @@
}
}
-void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_std)
+void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb)
{
- if (skb->len <= mss_std) {
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (skb->len <= tp->mss_cache_std ||
+ !(sk->sk_route_caps & NETIF_F_TSO)) {
/* Avoid the costly divide in the normal
* non-TSO case.
*/
@@ -451,10 +454,10 @@
} else {
unsigned int factor;
- factor = skb->len + (mss_std - 1);
- factor /= mss_std;
+ factor = skb->len + (tp->mss_cache_std - 1);
+ factor /= tp->mss_cache_std;
skb_shinfo(skb)->tso_segs = factor;
- skb_shinfo(skb)->tso_size = mss_std;
+ skb_shinfo(skb)->tso_size = tp->mss_cache_std;
}
}
@@ -525,8 +528,8 @@
}
/* Fix up tso_factor for both original and new SKB. */
- tcp_set_skb_tso_segs(skb, tp->mss_cache_std);
- tcp_set_skb_tso_segs(buff, tp->mss_cache_std);
+ tcp_set_skb_tso_segs(sk, skb);
+ tcp_set_skb_tso_segs(sk, buff);
if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) {
tp->lost_out += tcp_skb_pcount(skb);
@@ -601,7 +604,7 @@
* factor and mss.
*/
if (tcp_skb_pcount(skb) > 1)
- tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb));
+ tcp_set_skb_tso_segs(sk, skb);
return 0;
}
@@ -752,7 +755,7 @@
mss_now = tcp_current_mss(sk, 1);
while ((skb = sk->sk_send_head) &&
- tcp_snd_test(tp, skb, mss_now,
+ tcp_snd_test(sk, skb, mss_now,
tcp_skb_is_last(sk, skb) ? nonagle :
TCP_NAGLE_PUSH)) {
if (skb->len > mss_now) {
@@ -1676,7 +1679,7 @@
tp->mss_cache = tp->mss_cache_std;
}
} else if (!tcp_skb_pcount(skb))
- tcp_set_skb_tso_segs(skb, tp->mss_cache_std);
+ tcp_set_skb_tso_segs(sk, skb);
TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
TCP_SKB_CB(skb)->when = tcp_time_stamp;