tcp: remove loop to compute wscale (19bf6261) · Commits · 戴 / test

We can remove the loop and conditional branches and compute wscale efficiently thanks to ilog2() Signed-off-by:

net/ipv4/tcp_output.c

+3 −5

Original line number	Diff line number	Diff line
		@@ -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);