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Commit b1964b5f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: constify tcp_openreq_init_rwin() 



Soon, listener socket wont be locked when tcp_openreq_init_rwin()
is called. We need to read socket fields once, as their value
could change under us.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b40cf18e

include/net/tcp.h

+2 −1
Original line number Diff line number Diff line
@@ -1207,7 +1207,8 @@ static inline int tcp_full_space(const struct sock *sk) 
}



extern void tcp_openreq_init_rwin(struct request_sock *req,

				  struct sock *sk, struct dst_entry *dst);

				  const struct sock *sk_listener,

				  const struct dst_entry *dst);



void tcp_enter_memory_pressure(struct sock *sk);

net/ipv4/tcp_minisocks.c

+18 −10
Original line number Diff line number Diff line
@@ -362,27 +362,35 @@ void tcp_twsk_destructor(struct sock *sk) 
}

EXPORT_SYMBOL_GPL(tcp_twsk_destructor);



/* Warning : This function is called without sk_listener being locked.

 * Be sure to read socket fields once, as their value could change under us.

 */

void tcp_openreq_init_rwin(struct request_sock *req,

			   struct sock *sk, struct dst_entry *dst)

			   const struct sock *sk_listener,

			   const struct dst_entry *dst)

{

	struct inet_request_sock *ireq = inet_rsk(req);

	struct tcp_sock *tp = tcp_sk(sk);

	__u8 rcv_wscale;

	const struct tcp_sock *tp = tcp_sk(sk_listener);

	u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);

	int full_space = tcp_full_space(sk_listener);

	int mss = dst_metric_advmss(dst);

	u32 window_clamp;

	__u8 rcv_wscale;



	if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss)

		mss = tp->rx_opt.user_mss;

	if (user_mss && user_mss < mss)

		mss = user_mss;



	window_clamp = READ_ONCE(tp->window_clamp);

	/* Set this up on the first call only */

	req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW);

	req->window_clamp = window_clamp ? : dst_metric(dst, RTAX_WINDOW);



	/* limit the window selection if the user enforce a smaller rx buffer */

	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK &&

	    (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0))

		req->window_clamp = tcp_full_space(sk);

	if (sk_listener->sk_userlocks & SOCK_RCVBUF_LOCK &&

	    (req->window_clamp > full_space || req->window_clamp == 0))

		req->window_clamp = full_space;



	/* tcp_full_space because it is guaranteed to be the first packet */

	tcp_select_initial_window(tcp_full_space(sk),

	tcp_select_initial_window(full_space,

		mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),

		&req->rcv_wnd,

		&req->window_clamp,