From 19bf62613a800ef4ffa26cbae6b723d9f46740ed Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 29 Nov 2018 07:56:20 -0800 Subject: tcp: remove loop to compute wscale We can remove the loop and conditional branches and compute wscale efficiently thanks to ilog2() Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c5dc4c4fdadd..e4c1e51b18c1 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -233,16 +233,14 @@ void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, if (init_rcv_wnd) *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); - (*rcv_wscale) = 0; + *rcv_wscale = 0; if (wscale_ok) { /* Set window scaling on max possible window */ space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]); space = max_t(u32, space, sysctl_rmem_max); space = min_t(u32, space, *window_clamp); - while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) { - space >>= 1; - (*rcv_wscale)++; - } + *rcv_wscale = clamp_t(int, ilog2(space) - 15, + 0, TCP_MAX_WSCALE); } /* Set the clamp no higher than max representable value */ (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); -- cgit v1.2.3-59-g8ed1b