net: Adjust sk_gso_max_size once when set

sk_gso_max_size is set based on the dst dev. Both users of it
adjust the value by the same offset - (MAX_TCP_HEADER + 1). Rather
than compute the same adjusted value on each call do the adjustment
once when set.

Signed-off-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220125024511.27480-1-dsahern@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/sock.c b/net/core/sock.c
index 4ff806d..cccf21f 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2266,6 +2266,7 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst)
                        sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM;
                        /* pairs with the WRITE_ONCE() in netif_set_gso_max_size() */
                        sk->sk_gso_max_size = READ_ONCE(dst->dev->gso_max_size);
+                       sk->sk_gso_max_size -= (MAX_TCP_HEADER + 1);
                        /* pairs with the WRITE_ONCE() in netif_set_gso_max_segs() */
                        max_segs = max_t(u32, READ_ONCE(dst->dev->gso_max_segs), 1);
                }

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 78e8146..cf1ce81 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -894,8 +894,7 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
                return mss_now;
 
        /* Note : tcp_tso_autosize() will eventually split this later */
-       new_size_goal = sk->sk_gso_max_size - 1 - MAX_TCP_HEADER;
-       new_size_goal = tcp_bound_to_half_wnd(tp, new_size_goal);
+       new_size_goal = tcp_bound_to_half_wnd(tp, sk->sk_gso_max_size);
 
        /* We try hard to avoid divides here */
        size_goal = tp->gso_segs * mss_now;

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5079832..11c06b9 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1960,7 +1960,7 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
 
        bytes = min_t(unsigned long,
                      sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift),
-                     sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
+                     sk->sk_gso_max_size);
 
        /* Goal is to send at least one packet per ms,
         * not one big TSO packet every 100 ms.