Re: [PATCH net-next] net: add net device refcount tracker to struct packet_type

From: Eric Dumazet <redacted>

Most notable changes are in af_packet, tipc ones are trivial.

Signed-off-by: Eric Dumazet <redacted>
Cc: Jon Maloy <jmaloy@redhat.com>
Cc: Ying Xue <redacted>
---
  include/linux/netdevice.h |  1 +
  net/packet/af_packet.c    | 14 +++++++++++---
  net/tipc/bearer.c         |  4 ++--
  3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 235d5d082f1a446c8d898ffcc5b1983df7c04f35..0ed0a6f0d69d3565c1db9203040838801cd71e99 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h

@@ -2533,6 +2533,7 @@ struct packet_type {
  	__be16			type;	/* This is really htons(ether_type). */
  	bool			ignore_outgoing;
  	struct net_device	*dev;	/* NULL is wildcarded here	     */
+	netdevice_tracker	dev_tracker;
  	int			(*func) (struct sk_buff *,
  					 struct net_device *,
  					 struct packet_type *,

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index a1ffdb48cc474dcf91bddfd1ab96386a89c20375..71854a16afbbc1c06005e48a65cdb7007d61b019 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c

@@ -3109,7 +3109,7 @@ static int packet_release(struct socket *sock)
  	packet_cached_dev_reset(po);
  
  	if (po->prot_hook.dev) {
-		dev_put(po->prot_hook.dev);
+		dev_put_track(po->prot_hook.dev, &po->prot_hook.dev_tracker);
  		po->prot_hook.dev = NULL;
  	}
  	spin_unlock(&po->bind_lock);

@@ -3217,18 +3217,25 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
  		WRITE_ONCE(po->num, proto);
  		po->prot_hook.type = proto;
  
+		dev_put_track(dev_curr, &po->prot_hook.dev_tracker);
+		dev_curr = NULL;
+
  		if (unlikely(unlisted)) {
  			dev_put(dev);
  			po->prot_hook.dev = NULL;
  			WRITE_ONCE(po->ifindex, -1);
  			packet_cached_dev_reset(po);
  		} else {
+			if (dev)
+				netdev_tracker_alloc(dev,
+						     &po->prot_hook.dev_tracker,
+						     GFP_ATOMIC);
  			po->prot_hook.dev = dev;
  			WRITE_ONCE(po->ifindex, dev ? dev->ifindex : 0);
  			packet_cached_dev_assign(po, dev);
  		}
  	}
-	dev_put(dev_curr);
+	dev_put_track(dev_curr, &po->prot_hook.dev_tracker);
  
  	if (proto == 0 || !need_rehook)
  		goto out_unlock;

@@ -4138,7 +4145,8 @@ static int packet_notifier(struct notifier_block *this,
  				if (msg == NETDEV_UNREGISTER) {
  					packet_cached_dev_reset(po);
  					WRITE_ONCE(po->ifindex, -1);
-					dev_put(po->prot_hook.dev);
+					dev_put_track(po->prot_hook.dev,
+						      &po->prot_hook.dev_tracker);
  					po->prot_hook.dev = NULL;
  				}
  				spin_unlock(&po->bind_lock);

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 60bc74b76adc5909fdb5294f205229682a09d031..473a790f58943537896c16c72b60061b5ffe6840 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c

@@ -787,7 +787,7 @@ int tipc_attach_loopback(struct net *net)
  	if (!dev)
  		return -ENODEV;
  
-	dev_hold(dev);
+	dev_hold_track(dev, &tn->loopback_pt.dev_tracker, GFP_KERNEL);
  	tn->loopback_pt.dev = dev;
  	tn->loopback_pt.type = htons(ETH_P_TIPC);
  	tn->loopback_pt.func = tipc_loopback_rcv_pkt;

@@ -800,7 +800,7 @@ void tipc_detach_loopback(struct net *net)
  	struct tipc_net *tn = tipc_net(net);
  
  	dev_remove_pack(&tn->loopback_pt);
-	dev_put(net->loopback_dev);
+	dev_put_track(net->loopback_dev, &tn->loopback_pt.dev_tracker);
  }
  
  /* Caller should hold rtnl_lock to protect the bearer */