net-procfs: show net devices bound packet types

After commit:7866a621 ("dev: add per net_device packet type chains"),
we can not get packet types that are bound to a specified net device by
/proc/net/ptype, this patch fix the regression.

Run "tcpdump -i ens192 udp -nns0" Before and after apply this patch:

Before:
  [root@localhost ~]# cat /proc/net/ptype
  Type Device      Function
  0800          ip_rcv
  0806          arp_rcv
  86dd          ipv6_rcv

After:
  [root@localhost ~]# cat /proc/net/ptype
  Type Device      Function
  ALL  ens192   tpacket_rcv
  0800          ip_rcv
  0806          arp_rcv
  86dd          ipv6_rcv

v1 -> v2:
  - fix the regression rather than adding new /proc API as
    suggested by Stephen Hemminger.

Fixes: 7866a621 ("dev: add per net_device packet type chains")
Signed-off-by: Jianguo Wu <wujianguo@chinatelecom.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/net-procfs.c

@@ -190,12 +190,23 @@ static const struct seq_operations softnet_seq_ops = {
 	.show  = softnet_seq_show,
 };
 
-static void *ptype_get_idx(loff_t pos)
+static void *ptype_get_idx(struct seq_file *seq, loff_t pos)
 {
+	struct list_head *ptype_list = NULL;
 	struct packet_type *pt = NULL;
+	struct net_device *dev;
 	loff_t i = 0;
 	int t;
 
+	for_each_netdev_rcu(seq_file_net(seq), dev) {
+		ptype_list = &dev->ptype_all;
+		list_for_each_entry_rcu(pt, ptype_list, list) {
+			if (i == pos)
+				return pt;
+			++i;
+		}
+	}
+
 	list_for_each_entry_rcu(pt, &ptype_all, list) {
 		if (i == pos)
 			return pt;
@@ -216,22 +227,40 @@ static void *ptype_seq_start(struct seq_file *seq, loff_t *pos)
 	__acquires(RCU)
 {
 	rcu_read_lock();
-	return *pos ? ptype_get_idx(*pos - 1) : SEQ_START_TOKEN;
+	return *pos ? ptype_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
 }
 
 static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
+	struct net_device *dev;
 	struct packet_type *pt;
 	struct list_head *nxt;
 	int hash;
 
 	++*pos;
 	if (v == SEQ_START_TOKEN)
-		return ptype_get_idx(0);
+		return ptype_get_idx(seq, 0);
 
 	pt = v;
 	nxt = pt->list.next;
+	if (pt->dev) {
+		if (nxt != &pt->dev->ptype_all)
+			goto found;
+
+		dev = pt->dev;
+		for_each_netdev_continue_rcu(seq_file_net(seq), dev) {
+			if (!list_empty(&dev->ptype_all)) {
+				nxt = dev->ptype_all.next;
+				goto found;
+			}
+		}
+
+		nxt = ptype_all.next;
+		goto ptype_all;
+	}
+
 	if (pt->type == htons(ETH_P_ALL)) {
+ptype_all:
 		if (nxt != &ptype_all)
 			goto found;
 		hash = 0;