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tcp: constify tcp_openreq_init_rwin()

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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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-09-25 07:39:09 -07:00 committed by David S. Miller
parent b40cf18ef7
commit b1964b5fce
2 changed files with 20 additions and 11 deletions
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3
include/net/tcp.h
View file

@ -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);

28
net/ipv4/tcp_minisocks.c
View file

@ -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,