Merge branch 'netdev-tracking'

Jakub Kicinski says:

====================
net: create device lookup API with reference tracking

We still see dev_hold() / dev_put() calls without reference tracker
getting added in new code. dev_get_by_name() / dev_get_by_index()
seem to be one of the sources of those. Provide appropriate helpers.
Allocating the tracker can obviously be done with an additional call
to netdev_tracker_alloc(), but a single API feels cleaner.

v2:
 - fix a dev_put() in ethtool
v1: https://lore.kernel.org/all/20230609183207.1466075-1-kuba@kernel.org/
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -3124,6 +3124,10 @@ struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
 					    struct sock *sk);
 struct net_device *dev_get_by_index(struct net *net, int ifindex);
 struct net_device *__dev_get_by_index(struct net *net, int ifindex);
+struct net_device *netdev_get_by_index(struct net *net, int ifindex,
+				       netdevice_tracker *tracker, gfp_t gfp);
+struct net_device *netdev_get_by_name(struct net *net, const char *name,
+				      netdevice_tracker *tracker, gfp_t gfp);
 struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
 struct net_device *dev_get_by_napi_id(unsigned int napi_id);
 int dev_restart(struct net_device *dev);

net/core/dev.c

@@ -758,29 +758,43 @@ struct net_device *dev_get_by_name_rcu(struct net *net, const char *name)
 }
 EXPORT_SYMBOL(dev_get_by_name_rcu);
 
+/* Deprecated for new users, call netdev_get_by_name() instead */
+struct net_device *dev_get_by_name(struct net *net, const char *name)
+{
+	struct net_device *dev;
+
+	rcu_read_lock();
+	dev = dev_get_by_name_rcu(net, name);
+	dev_hold(dev);
+	rcu_read_unlock();
+	return dev;
+}
+EXPORT_SYMBOL(dev_get_by_name);
+
 /**
- *	dev_get_by_name		- find a device by its name
+ *	netdev_get_by_name() - find a device by its name
  *	@net: the applicable net namespace
  *	@name: name to find
+ *	@tracker: tracking object for the acquired reference
+ *	@gfp: allocation flags for the tracker
  *
  *	Find an interface by name. This can be called from any
  *	context and does its own locking. The returned handle has
- *	the usage count incremented and the caller must use dev_put() to
+ *	the usage count incremented and the caller must use netdev_put() to
  *	release it when it is no longer needed. %NULL is returned if no
  *	matching device is found.
  */
-
-struct net_device *dev_get_by_name(struct net *net, const char *name)
+struct net_device *netdev_get_by_name(struct net *net, const char *name,
+				      netdevice_tracker *tracker, gfp_t gfp)
 {
 	struct net_device *dev;
 
-	rcu_read_lock();
-	dev = dev_get_by_name_rcu(net, name);
-	dev_hold(dev);
-	rcu_read_unlock();
+	dev = dev_get_by_name(net, name);
+	if (dev)
+		netdev_tracker_alloc(dev, tracker, gfp);
 	return dev;
 }
-EXPORT_SYMBOL(dev_get_by_name);
+EXPORT_SYMBOL(netdev_get_by_name);
 
 /**
  *	__dev_get_by_index - find a device by its ifindex
@@ -831,29 +845,42 @@ struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex)
 }
 EXPORT_SYMBOL(dev_get_by_index_rcu);
 
+/* Deprecated for new users, call netdev_get_by_index() instead */
+struct net_device *dev_get_by_index(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+
+	rcu_read_lock();
+	dev = dev_get_by_index_rcu(net, ifindex);
+	dev_hold(dev);
+	rcu_read_unlock();
+	return dev;
+}
+EXPORT_SYMBOL(dev_get_by_index);
 
 /**
- *	dev_get_by_index - find a device by its ifindex
+ *	netdev_get_by_index() - find a device by its ifindex
  *	@net: the applicable net namespace
  *	@ifindex: index of device
+ *	@tracker: tracking object for the acquired reference
+ *	@gfp: allocation flags for the tracker
  *
  *	Search for an interface by index. Returns NULL if the device
  *	is not found or a pointer to the device. The device returned has
  *	had a reference added and the pointer is safe until the user calls
- *	dev_put to indicate they have finished with it.
+ *	netdev_put() to indicate they have finished with it.
  */
-
-struct net_device *dev_get_by_index(struct net *net, int ifindex)
+struct net_device *netdev_get_by_index(struct net *net, int ifindex,
+				       netdevice_tracker *tracker, gfp_t gfp)
 {
 	struct net_device *dev;
 
-	rcu_read_lock();
-	dev = dev_get_by_index_rcu(net, ifindex);
-	dev_hold(dev);
-	rcu_read_unlock();
+	dev = dev_get_by_index(net, ifindex);
+	if (dev)
+		netdev_tracker_alloc(dev, tracker, gfp);
 	return dev;
 }
-EXPORT_SYMBOL(dev_get_by_index);
+EXPORT_SYMBOL(netdev_get_by_index);
 
 /**
  *	dev_get_by_napi_id - find a device by napi_id

net/core/netpoll.c

@@ -690,7 +690,7 @@ int netpoll_setup(struct netpoll *np)
 		err = -ENODEV;
 		goto unlock;
 	}
-	dev_hold(ndev);
+	netdev_hold(ndev, &np->dev_tracker, GFP_KERNEL);
 
 	if (netdev_master_upper_dev_get(ndev)) {
 		np_err(np, "%s is a slave device, aborting\n", np->dev_name);
@@ -783,12 +783,11 @@ int netpoll_setup(struct netpoll *np)
 	err = __netpoll_setup(np, ndev);
 	if (err)
 		goto put;
-	netdev_tracker_alloc(ndev, &np->dev_tracker, GFP_KERNEL);
 	rtnl_unlock();
 	return 0;
 
 put:
-	dev_put(ndev);
+	netdev_put(ndev, &np->dev_tracker);
 unlock:
 	rtnl_unlock();
 	return err;

net/ethtool/netlink.c

@@ -115,7 +115,8 @@ int ethnl_parse_header_dev_get(struct ethnl_req_info *req_info,
 	if (tb[ETHTOOL_A_HEADER_DEV_INDEX]) {
 		u32 ifindex = nla_get_u32(tb[ETHTOOL_A_HEADER_DEV_INDEX]);
 
-		dev = dev_get_by_index(net, ifindex);
+		dev = netdev_get_by_index(net, ifindex, &req_info->dev_tracker,
+					  GFP_KERNEL);
 		if (!dev) {
 			NL_SET_ERR_MSG_ATTR(extack,
 					    tb[ETHTOOL_A_HEADER_DEV_INDEX],
@@ -125,13 +126,14 @@ int ethnl_parse_header_dev_get(struct ethnl_req_info *req_info,
 		/* if both ifindex and ifname are passed, they must match */
 		if (devname_attr &&
 		    strncmp(dev->name, nla_data(devname_attr), IFNAMSIZ)) {
-			dev_put(dev);
+			netdev_put(dev, &req_info->dev_tracker);
 			NL_SET_ERR_MSG_ATTR(extack, header,
 					    "ifindex and name do not match");
 			return -ENODEV;
 		}
 	} else if (devname_attr) {
-		dev = dev_get_by_name(net, nla_data(devname_attr));
+		dev = netdev_get_by_name(net, nla_data(devname_attr),
+					 &req_info->dev_tracker, GFP_KERNEL);
 		if (!dev) {
 			NL_SET_ERR_MSG_ATTR(extack, devname_attr,
 					    "no device matches name");
@@ -144,8 +146,6 @@ int ethnl_parse_header_dev_get(struct ethnl_req_info *req_info,
 	}
 
 	req_info->dev = dev;
-	if (dev)
-		netdev_tracker_alloc(dev, &req_info->dev_tracker, GFP_KERNEL);
 	req_info->flags = flags;
 	return 0;
 }

net/ipv6/route.c

@@ -3503,6 +3503,7 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 		 struct fib6_config *cfg, gfp_t gfp_flags,
 		 struct netlink_ext_ack *extack)
 {
+	netdevice_tracker *dev_tracker = &fib6_nh->fib_nh_dev_tracker;
 	struct net_device *dev = NULL;
 	struct inet6_dev *idev = NULL;
 	int addr_type;
@@ -3520,7 +3521,8 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 
 	err = -ENODEV;
 	if (cfg->fc_ifindex) {
-		dev = dev_get_by_index(net, cfg->fc_ifindex);
+		dev = netdev_get_by_index(net, cfg->fc_ifindex,
+					  dev_tracker, gfp_flags);
 		if (!dev)
 			goto out;
 		idev = in6_dev_get(dev);
@@ -3554,11 +3556,11 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 		/* hold loopback dev/idev if we haven't done so. */
 		if (dev != net->loopback_dev) {
 			if (dev) {
-				dev_put(dev);
+				netdev_put(dev, dev_tracker);
 				in6_dev_put(idev);
 			}
 			dev = net->loopback_dev;
-			dev_hold(dev);
+			netdev_hold(dev, dev_tracker, gfp_flags);
 			idev = in6_dev_get(dev);
 			if (!idev) {
 				err = -ENODEV;
@@ -3610,8 +3612,6 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 	}
 
 	fib6_nh->fib_nh_dev = dev;
-	netdev_tracker_alloc(dev, &fib6_nh->fib_nh_dev_tracker, gfp_flags);
-
 	fib6_nh->fib_nh_oif = dev->ifindex;
 	err = 0;
 out:
@@ -3621,7 +3621,7 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 	if (err) {
 		lwtstate_put(fib6_nh->fib_nh_lws);
 		fib6_nh->fib_nh_lws = NULL;
-		dev_put(dev);
+		netdev_put(dev, dev_tracker);
 	}
 
 	return err;