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>

1 files changed, 45 insertions, 18 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index c2456b3667fe..63abb0463c24 100644
--- a/net/core/dev.c
+++ b/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