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authorEric Dumazet <edumazet@google.com>2018-11-29 07:56:20 -0800
committerDavid S. Miller <davem@davemloft.net>2018-11-29 11:10:14 -0800
commit19bf62613a800ef4ffa26cbae6b723d9f46740ed (patch)
tree7a48396a78634310d66e156caf70a5ef61451ad5 /net/ipv4/tcp_output.c
parentdcc6abae0f473a67543ce651fbfb6b15452876f6 (diff)
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 <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_output.c')
-rw-r--r--net/ipv4/tcp_output.c8
1 files changed, 3 insertions, 5 deletions
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);