net: tcp_probe: also include rcv_wnd next to snd_wnd

It is helpful to sometimes know the TCP window sizes of an established
socket e.g. to confirm that window scaling is working or to tweak the
window size to improve high-latency connections, etc etc. Currently the
TCP snooper only exports the send window size, but not the receive window
size. Therefore, also add the receive window size to the end of the
output line.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_probe.c

@@ -60,6 +60,7 @@ struct tcp_log {
 	u32	snd_nxt;
 	u32	snd_una;
 	u32	snd_wnd;
+	u32	rcv_wnd;
 	u32	snd_cwnd;
 	u32	ssthresh;
 	u32	srtt;
@@ -116,6 +117,7 @@ static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 			p->snd_una = tp->snd_una;
 			p->snd_cwnd = tp->snd_cwnd;
 			p->snd_wnd = tp->snd_wnd;
+			p->rcv_wnd = tp->rcv_wnd;
 			p->ssthresh = tcp_current_ssthresh(sk);
 			p->srtt = tp->srtt >> 3;
 
@@ -157,13 +159,13 @@ static int tcpprobe_sprint(char *tbuf, int n)
 		= ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
 
 	return scnprintf(tbuf, n,
-			"%lu.%09lu %pI4:%u %pI4:%u %d %#x %#x %u %u %u %u\n",
+			"%lu.%09lu %pI4:%u %pI4:%u %d %#x %#x %u %u %u %u %u\n",
 			(unsigned long) tv.tv_sec,
 			(unsigned long) tv.tv_nsec,
 			&p->saddr, ntohs(p->sport),
 			&p->daddr, ntohs(p->dport),
 			p->length, p->snd_nxt, p->snd_una,
-			p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt);
+			p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt, p->rcv_wnd);
 }
 
 static ssize_t tcpprobe_read(struct file *file, char __user *buf,