[TCP]: Avoid a divide in tcp_mtu_probing()
Eric Dumazet [Fri, 21 Dec 2007 13:58:29 +0000 (05:58 -0800)]
tcp_mtu_to_mss() being signed, compiler might emit an integer divide
to compute tcp_mtu_to_mss()/2 .

Using a right shift is OK here and less expensive.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_timer.c

index ea111e9..ea85bc0 100644 (file)
@@ -125,7 +125,7 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
                        struct tcp_sock *tp = tcp_sk(sk);
                        int mss;
 
-                       mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)/2;
+                       mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
                        mss = min(sysctl_tcp_base_mss, mss);
                        mss = max(mss, 68 - tp->tcp_header_len);
                        icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);