rxrpc: Add /proc/net/rxrpc/peers to display peer list

Add /proc/net/rxrpc/peers to display the list of peers currently active.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rxrpc/ar-internal.h

@@ -1062,6 +1062,7 @@ void rxrpc_put_peer(struct rxrpc_peer *);
  */
 extern const struct seq_operations rxrpc_call_seq_ops;
 extern const struct seq_operations rxrpc_connection_seq_ops;
+extern const struct seq_operations rxrpc_peer_seq_ops;
 
 /*
  * recvmsg.c

net/rxrpc/net_ns.c

@@ -102,6 +102,9 @@ static __net_init int rxrpc_init_net(struct net *net)
 	proc_create_net("conns", 0444, rxnet->proc_net,
 			&rxrpc_connection_seq_ops,
 			sizeof(struct seq_net_private));
+	proc_create_net("peers", 0444, rxnet->proc_net,
+			&rxrpc_peer_seq_ops,
+			sizeof(struct seq_net_private));
 	return 0;
 
 err_proc:

net/rxrpc/proc.c

@@ -212,3 +212,129 @@ const struct seq_operations rxrpc_connection_seq_ops = {
 	.stop   = rxrpc_connection_seq_stop,
 	.show   = rxrpc_connection_seq_show,
 };
+
+/*
+ * generate a list of extant virtual peers in /proc/net/rxrpc/peers
+ */
+static int rxrpc_peer_seq_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_peer *peer;
+	time64_t now;
+	char lbuff[50], rbuff[50];
+
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq,
+			 "Proto Local                                          "
+			 " Remote                                         "
+			 " Use CW  MTU   LastUse          RTT Rc\n"
+			 );
+		return 0;
+	}
+
+	peer = list_entry(v, struct rxrpc_peer, hash_link);
+
+	sprintf(lbuff, "%pISpc", &peer->local->srx.transport);
+
+	sprintf(rbuff, "%pISpc", &peer->srx.transport);
+
+	now = ktime_get_seconds();
+	seq_printf(seq,
+		   "UDP   %-47.47s %-47.47s %3u"
+		   " %3u %5u %6llus %12llu %2u\n",
+		   lbuff,
+		   rbuff,
+		   atomic_read(&peer->usage),
+		   peer->cong_cwnd,
+		   peer->mtu,
+		   now - peer->last_tx_at,
+		   peer->rtt,
+		   peer->rtt_cursor);
+
+	return 0;
+}
+
+static void *rxrpc_peer_seq_start(struct seq_file *seq, loff_t *_pos)
+	__acquires(rcu)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	unsigned int bucket, n;
+	unsigned int shift = 32 - HASH_BITS(rxnet->peer_hash);
+	void *p;
+
+	rcu_read_lock();
+
+	if (*_pos >= UINT_MAX)
+		return NULL;
+
+	n = *_pos & ((1U << shift) - 1);
+	bucket = *_pos >> shift;
+	for (;;) {
+		if (bucket >= HASH_SIZE(rxnet->peer_hash)) {
+			*_pos = UINT_MAX;
+			return NULL;
+		}
+		if (n == 0) {
+			if (bucket == 0)
+				return SEQ_START_TOKEN;
+			*_pos += 1;
+			n++;
+		}
+
+		p = seq_hlist_start_rcu(&rxnet->peer_hash[bucket], n - 1);
+		if (p)
+			return p;
+		bucket++;
+		n = 1;
+		*_pos = (bucket << shift) | n;
+	}
+}
+
+static void *rxrpc_peer_seq_next(struct seq_file *seq, void *v, loff_t *_pos)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	unsigned int bucket, n;
+	unsigned int shift = 32 - HASH_BITS(rxnet->peer_hash);
+	void *p;
+
+	if (*_pos >= UINT_MAX)
+		return NULL;
+
+	bucket = *_pos >> shift;
+
+	p = seq_hlist_next_rcu(v, &rxnet->peer_hash[bucket], _pos);
+	if (p)
+		return p;
+
+	for (;;) {
+		bucket++;
+		n = 1;
+		*_pos = (bucket << shift) | n;
+
+		if (bucket >= HASH_SIZE(rxnet->peer_hash)) {
+			*_pos = UINT_MAX;
+			return NULL;
+		}
+		if (n == 0) {
+			*_pos += 1;
+			n++;
+		}
+
+		p = seq_hlist_start_rcu(&rxnet->peer_hash[bucket], n - 1);
+		if (p)
+			return p;
+	}
+}
+
+static void rxrpc_peer_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+
+const struct seq_operations rxrpc_peer_seq_ops = {
+	.start  = rxrpc_peer_seq_start,
+	.next   = rxrpc_peer_seq_next,
+	.stop   = rxrpc_peer_seq_stop,
+	.show   = rxrpc_peer_seq_show,
+};