tcp: diag: Dont report negative values for rx queue
Both netlink and /proc/net/tcp interfaces can report transient
negative values for rx queue.
ss ->
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB -6 6 127.0.0.1:45956 127.0.0.1:3333
netstat ->
tcp 4294967290 6 127.0.0.1:37784 127.0.0.1:3333 ESTABLISHED
This is because we dont lock socket while computing
tp->rcv_nxt - tp->copied_seq,
and another CPU can update copied_seq before rcv_next in RX path.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index fcbcd4f..939edb3 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -27,7 +27,7 @@
r->idiag_rqueue = sk->sk_ack_backlog;
r->idiag_wqueue = sk->sk_max_ack_backlog;
} else {
- r->idiag_rqueue = tp->rcv_nxt - tp->copied_seq;
+ r->idiag_rqueue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
r->idiag_wqueue = tp->write_seq - tp->snd_una;
}
if (info != NULL)