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 <eduma...@google.com>
---
include/net/tcp.h | 3 ++-
net/ipv4/tcp_minisocks.c | 28 ++++++++++++++++++----------
2 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 50af10ef1a3d..a89ec41fa3d9 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -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);
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6e23c36d26e9..e4fe62b6b106 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -361,27 +361,35 @@ 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,
--
2.6.0.rc2.230.g3dd15c0
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