tcp: simplify tcp_current_mss

There's very little need for most of the callsites to get
tp->xmit_goal_size updated. That will cost us divide as is,
so slice the function in two. Also, the only users of the
tp->xmit_goal_size are directly behind tcp_current_mss(),
so there's no need to store that variable into tcp_sock
at all! The drop of xmit_goal_size currently leaves 16-bit
hole and some reorganization would again be necessary to
change that (but I'm aiming to fill that hole with u16
xmit_goal_size_segs to cache the results of the remaining
divide to get that tso on regression).

Bring xmit_goal_size parts into tcp.c

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 11 insertions, 3 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 4b86ad71e054..ad2021ccc55a 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -248,7 +248,6 @@ struct tcp_sock {
         /* inet_connection_sock has to be the first member of tcp_sock */
         struct inet_connection_sock     inet_conn;
         u16     tcp_header_len; /* Bytes of tcp header to send          */
-        u16     xmit_size_goal; /* Goal for segmenting output packets   */
 
 /*
  *      Header prediction flags
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 255ca35bea05..e54c76d75495 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -481,7 +481,16 @@ static inline void tcp_clear_xmit_timers(struct sock *sk)
 }
 
 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
-extern unsigned int tcp_current_mss(struct sock *sk, int large);
+extern unsigned int tcp_current_mss(struct sock *sk);
+
+/* Bound MSS / TSO packet size with the half of the window */
+static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
+{
+        if (tp->max_window && pktsize > (tp->max_window >> 1))
+                return max(tp->max_window >> 1, 68U - tp->tcp_header_len);
+        else
+                return pktsize;
+}
 
 /* tcp.c */
 extern void tcp_get_info(struct sock *, struct tcp_info *);
@@ -822,7 +831,7 @@ static inline void tcp_push_pending_frames(struct sock *sk)
 {
         struct tcp_sock *tp = tcp_sk(sk);
 
-        __tcp_push_pending_frames(sk, tcp_current_mss(sk, 1), tp->nonagle);
+        __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
 }
 
 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)