Merge branch 'dev-hold-per-netns-rtnl-in-register-netdev'

Kuniyuki Iwashima says:

====================
dev: Hold per-netns RTNL in register_netdev().

Patch 1 adds rtnl_net_lock_killable() and Patch 2 uses it in
register_netdev() and converts it and unregister_netdev() to
per-netns RTNL.

With this and the netdev notifier series [0], ASSERT_RTNL_NET()
for NETDEV_REGISTER [1] wasn't fired on a simplest QEMU setup
like e1000 + x86_64_defconfig + CONFIG_DEBUG_NET_SMALL_RTNL.

[0]: https://lore.kernel.org/netdev/20250104063735.36945-1-kuniyu@amazon.com/

[1]:
---8<---
diff --git a/net/core/rtnl_net_debug.c b/net/core/rtnl_net_debug.c
index f406045cbd0e..c0c30929002e 100644
--- a/net/core/rtnl_net_debug.c
+++ b/net/core/rtnl_net_debug.c
@@ -21,7 +21,6 @@ static int rtnl_net_debug_event(struct notifier_block *nb,
 	case NETDEV_DOWN:
 	case NETDEV_REBOOT:
 	case NETDEV_CHANGE:
-	case NETDEV_REGISTER:
 	case NETDEV_UNREGISTER:
 	case NETDEV_CHANGEMTU:
 	case NETDEV_CHANGEADDR:
@@ -60,19 +59,10 @@ static int rtnl_net_debug_event(struct notifier_block *nb,
 		ASSERT_RTNL();
 		break;

-	/* Once an event fully supports RTNL_NET, move it here
-	 * and remove "if (0)" below.
-	 *
-	 * case NETDEV_XXX:
-	 *	ASSERT_RTNL_NET(net);
-	 *	break;
-	 */
-	}
-
-	/* Just to avoid unused-variable error for dev and net. */
-	if (0)
+	case NETDEV_REGISTER:
 		ASSERT_RTNL_NET(net);
+		break;
+	}

 	return NOTIFY_DONE;
 }
---8<---
====================

Link: https://patch.msgid.link/20250104082149.48493-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 3b9d132cbc9e..4bc2ee0b10b0 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -102,6 +102,7 @@ void __rtnl_net_unlock(struct net *net);
 void rtnl_net_lock(struct net *net);
 void rtnl_net_unlock(struct net *net);
 int rtnl_net_trylock(struct net *net);
+int rtnl_net_lock_killable(struct net *net);
 int rtnl_net_lock_cmp_fn(const struct lockdep_map *a, const struct lockdep_map *b);
 
 bool rtnl_net_is_locked(struct net *net);
@@ -138,6 +139,11 @@ static inline int rtnl_net_trylock(struct net *net)
 	return rtnl_trylock();
 }
 
+static inline int rtnl_net_lock_killable(struct net *net)
+{
+	return rtnl_lock_killable();
+}
+
 static inline void ASSERT_RTNL_NET(struct net *net)
 {
 	ASSERT_RTNL();