netdev - [PATCH v1 net-next 1/4] net: Convert netdev_chain to blocking

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Message-ID: <20250104063735.36945-2-kuniyu@amazon.com>
Date: Sat, 4 Jan 2025 15:37:32 +0900
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Simon Horman <horms@...nel.org>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net-next 1/4] net: Convert netdev_chain to blocking_notifier.

Once RTNL is converted to per-netns, nothing protects
netdev_chain.

A netdev notifier might disappear while being used by
raw_notifier_call_chain().

Let's convert netdev_chain to blocking_notifier to add
its dedicated rwsem.

Given netdev_chain is touched under RTNL by only one user
at the same time, adding rwsem is unlikely to cause regression.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 net/core/dev.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index e7223972b9aa..404f5bda821b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -444,7 +444,7 @@ static void unlist_netdevice(struct net_device *dev)
  *	Our notifier list
  */
 
-static RAW_NOTIFIER_HEAD(netdev_chain);
+static BLOCKING_NOTIFIER_HEAD(netdev_chain);
 
 /*
  *	Device drivers call our routines to queue packets here. We empty the
@@ -1770,7 +1770,7 @@ int register_netdevice_notifier(struct notifier_block *nb)
 	/* Close race with setup_net() and cleanup_net() */
 	down_write(&pernet_ops_rwsem);
 	rtnl_lock();
-	err = raw_notifier_chain_register(&netdev_chain, nb);
+	err = blocking_notifier_chain_register(&netdev_chain, nb);
 	if (err)
 		goto unlock;
 	if (dev_boot_phase)
@@ -1790,7 +1790,7 @@ int register_netdevice_notifier(struct notifier_block *nb)
 	for_each_net_continue_reverse(net)
 		call_netdevice_unregister_net_notifiers(nb, net);
 
-	raw_notifier_chain_unregister(&netdev_chain, nb);
+	blocking_notifier_chain_unregister(&netdev_chain, nb);
 	goto unlock;
 }
 EXPORT_SYMBOL(register_netdevice_notifier);
@@ -1817,7 +1817,7 @@ int unregister_netdevice_notifier(struct notifier_block *nb)
 	/* Close race with setup_net() and cleanup_net() */
 	down_write(&pernet_ops_rwsem);
 	rtnl_lock();
-	err = raw_notifier_chain_unregister(&netdev_chain, nb);
+	err = blocking_notifier_chain_unregister(&netdev_chain, nb);
 	if (err)
 		goto unlock;
 
@@ -1993,7 +1993,7 @@ int call_netdevice_notifiers_info(unsigned long val,
 	ret = raw_notifier_call_chain(&net->netdev_chain, val, info);
 	if (ret & NOTIFY_STOP_MASK)
 		return ret;
-	return raw_notifier_call_chain(&netdev_chain, val, info);
+	return blocking_notifier_call_chain(&netdev_chain, val, info);
 }
 
 /**
-- 
2.39.5 (Apple Git-154)