[net,v3,05/11] netdevsim: add dummy device notifiers

Commit Message

Stanislav Fomichev March 29, 2025, 6:56 p.m. UTC

In order to exercise and verify notifiers' locking assumptions,
register dummy notifiers (via register_netdevice_notifier_dev_net).
Share notifier event handler that enforces the assumptions with
lock_debug.c (rename and export rtnl_net_debug_event as
netdev_debug_event). Add ops lock asserts to netdev_debug_event.

Signed-off-by: Stanislav Fomichev <[e-mail]>
---
 drivers/net/netdevsim/netdev.c    | 10 ++++++++++
 drivers/net/netdevsim/netdevsim.h |  3 +++
 include/net/netdev_lock.h         | 11 +++++++++++
 net/core/lock_debug.c             | 14 +++++++++-----
 4 files changed, 33 insertions(+), 5 deletions(-)

Patch

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index b67af4651185..6188699aa241 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -939,6 +939,7 @@  static int nsim_init_netdevsim(struct netdevsim *ns)
 	ns->netdev->netdev_ops = &nsim_netdev_ops;
 	ns->netdev->stat_ops = &nsim_stat_ops;
 	ns->netdev->queue_mgmt_ops = &nsim_queue_mgmt_ops;
+	netdev_lockdep_set_classes(ns->netdev);
 
 	err = nsim_udp_tunnels_info_create(ns->nsim_dev, ns->netdev);
 	if (err)
@@ -960,6 +961,11 @@  static int nsim_init_netdevsim(struct netdevsim *ns)
 	if (err)
 		goto err_ipsec_teardown;
 	rtnl_unlock();
+
+	ns->nb.notifier_call = netdev_debug_event;
+	if (register_netdevice_notifier_dev_net(ns->netdev, &ns->nb, &ns->nn))
+		ns->nb.notifier_call = NULL;
+
 	return 0;
 
 err_ipsec_teardown:
@@ -1043,6 +1049,10 @@  void nsim_destroy(struct netdevsim *ns)
 	debugfs_remove(ns->qr_dfs);
 	debugfs_remove(ns->pp_dfs);
 
+	if (ns->nb.notifier_call)
+		unregister_netdevice_notifier_dev_net(ns->netdev, &ns->nb,
+						      &ns->nn);
+
 	rtnl_lock();
 	peer = rtnl_dereference(ns->peer);
 	if (peer)
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 665020d18f29..d04401f0bdf7 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -144,6 +144,9 @@  struct netdevsim {
 
 	struct nsim_ethtool ethtool;
 	struct netdevsim __rcu *peer;
+
+	struct notifier_block nb;
+	struct netdev_net_notifier nn;
 };
 
 struct netdevsim *
diff --git a/include/net/netdev_lock.h b/include/net/netdev_lock.h
index 1c0c9a94cc22..5f712de5bf8a 100644
--- a/include/net/netdev_lock.h
+++ b/include/net/netdev_lock.h
@@ -98,4 +98,15 @@  static inline int netdev_lock_cmp_fn(const struct lockdep_map *a,
 				  &qdisc_xmit_lock_key);	\
 }
 
+#if IS_ENABLED(CONFIG_DEBUG_NET)
+int netdev_debug_event(struct notifier_block *nb, unsigned long event,
+		       void *ptr);
+#else
+static inline int netdev_debug_event(struct notifier_block *nb,
+				     unsigned long event, void *ptr)
+{
+	return 0;
+}
+#endif
+
 #endif
diff --git a/net/core/lock_debug.c b/net/core/lock_debug.c
index 7ecd28cc1c22..506899164f31 100644
--- a/net/core/lock_debug.c
+++ b/net/core/lock_debug.c
@@ -6,10 +6,11 @@ 
 #include <linux/notifier.h>
 #include <linux/rtnetlink.h>
 #include <net/net_namespace.h>
+#include <net/netdev_lock.h>
 #include <net/netns/generic.h>
 
-static int rtnl_net_debug_event(struct notifier_block *nb,
-				unsigned long event, void *ptr)
+int netdev_debug_event(struct notifier_block *nb, unsigned long event,
+		       void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct net *net = dev_net(dev);
@@ -17,11 +18,13 @@  static int rtnl_net_debug_event(struct notifier_block *nb,
 
 	/* Keep enum and don't add default to trigger -Werror=switch */
 	switch (cmd) {
+	case NETDEV_REGISTER:
 	case NETDEV_UP:
+		netdev_ops_assert_locked(dev);
+		fallthrough;
 	case NETDEV_DOWN:
 	case NETDEV_REBOOT:
 	case NETDEV_CHANGE:
-	case NETDEV_REGISTER:
 	case NETDEV_UNREGISTER:
 	case NETDEV_CHANGEMTU:
 	case NETDEV_CHANGEADDR:
@@ -66,6 +69,7 @@  static int rtnl_net_debug_event(struct notifier_block *nb,
 
 	return NOTIFY_DONE;
 }
+EXPORT_SYMBOL_GPL(netdev_debug_event);
 
 static int rtnl_net_debug_net_id;
 
@@ -74,7 +78,7 @@  static int __net_init rtnl_net_debug_net_init(struct net *net)
 	struct notifier_block *nb;
 
 	nb = net_generic(net, rtnl_net_debug_net_id);
-	nb->notifier_call = rtnl_net_debug_event;
+	nb->notifier_call = netdev_debug_event;
 
 	return register_netdevice_notifier_net(net, nb);
 }
@@ -95,7 +99,7 @@  static struct pernet_operations rtnl_net_debug_net_ops __net_initdata = {
 };
 
 static struct notifier_block rtnl_net_debug_block = {
-	.notifier_call = rtnl_net_debug_event,
+	.notifier_call = netdev_debug_event,
 };
 
 static int __init rtnl_net_debug_init(void)