tcp: tcp_tso_autosize() minimum is one packet

By making sure sk->sk_gso_max_segs minimal value is one,
and sysctl_tcp_min_tso_segs minimal value is one as well,
tcp_tso_autosize() will return a non zero value.

We can then revert 843925f33fcc293d80acf2c5c8a78adf3344d49b
("tcp: Do not apply TSO segment limit to non-TSO packets")
and save few cpu cycles in fast path.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/sock.c b/net/core/sock.c
index 29124fc..e72633c 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1581,6 +1581,8 @@ EXPORT_SYMBOL_GPL(sk_clone_lock);
 
 void sk_setup_caps(struct sock *sk, struct dst_entry *dst)
 {
+       u32 max_segs = 1;
+
        __sk_dst_set(sk, dst);
        sk->sk_route_caps = dst->dev->features;
        if (sk->sk_route_caps & NETIF_F_GSO)
@@ -1592,9 +1594,10 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst)
                } else {
                        sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM;
                        sk->sk_gso_max_size = dst->dev->gso_max_size;
-                       sk->sk_gso_max_segs = dst->dev->gso_max_segs;
+                       max_segs = max_t(u32, dst->dev->gso_max_segs, 1);
                }
        }
+       sk->sk_gso_max_segs = max_segs;
 }
 EXPORT_SYMBOL_GPL(sk_setup_caps);
 

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 841de32..e648927 100644 (file)
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -702,7 +702,7 @@ static struct ctl_table ipv4_table[] = {
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
-               .extra1         = &zero,
+               .extra1         = &one,
                .extra2         = &gso_max_segs,
        },
        {

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 534e5fd..190538a 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2088,7 +2088,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
                if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now)))
                        break;
 
-               if (tso_segs == 1 || !max_segs) {
+               if (tso_segs == 1) {
                        if (unlikely(!tcp_nagle_test(tp, skb, mss_now,
                                                     (tcp_skb_is_last(sk, skb) ?
                                                      nonagle : TCP_NAGLE_PUSH))))
@@ -2101,7 +2101,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
                }
 
                limit = mss_now;
-               if (tso_segs > 1 && max_segs && !tcp_urg_mode(tp))
+               if (tso_segs > 1 && !tcp_urg_mode(tp))
                        limit = tcp_mss_split_point(sk, skb, mss_now,
                                                    min_t(unsigned int,
                                                          cwnd_quota,