This is a note to let you know that I've just added the patch titled
net: make netdev_lock() protect netdev->reg_state
to the 6.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-make-netdev_lock-protect-netdev-reg_state.patch
and it can be found in the queue-6.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9ecd605aef6d75542cf0ec6864c4602deaf809c6
Author: Jakub Kicinski <kuba@xxxxxxxxxx>
Date: Tue Jan 14 19:53:10 2025 -0800
net: make netdev_lock() protect netdev->reg_state
[ Upstream commit 5fda3f35349b6b7f22f5f5095a3821261d515075 ]
Protect writes to netdev->reg_state with netdev_lock().
From now on holding netdev_lock() is sufficient to prevent
the net_device from getting unregistered, so code which
wants to hold just a single netdev around no longer needs
to hold rtnl_lock.
We do not protect the NETREG_UNREGISTERED -> NETREG_RELEASED
transition. We'd need to move mutex_destroy(netdev->lock)
to .release, but the real reason is that trying to stop
the unregistration process mid-way would be unsafe / crazy.
Taking references on such devices is not safe, either.
So the intended semantics are to lock REGISTERED devices.
Reviewed-by: Joe Damato <jdamato@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://patch.msgid.link/20250115035319.559603-3-kuba@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Stable-dep-of: 6bc7e4eb0499 ("Revert "net: skb: introduce and use a single page frag cache"")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4b2964d0d885e..e0a8093c9be80 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2446,7 +2446,7 @@ struct net_device {
* Should always be taken using netdev_lock() / netdev_unlock() helpers.
* Drivers are free to use it for other protection.
*
- * Protects: @net_shaper_hierarchy.
+ * Protects: @reg_state, @net_shaper_hierarchy.
* Ordering: take after rtnl_lock.
*/
struct mutex lock;
diff --git a/net/core/dev.c b/net/core/dev.c
index c5e5b827bb800..d1e8613151a4a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10687,7 +10687,9 @@ int register_netdevice(struct net_device *dev)
ret = netdev_register_kobject(dev);
+ netdev_lock(dev);
WRITE_ONCE(dev->reg_state, ret ? NETREG_UNREGISTERED : NETREG_REGISTERED);
+ netdev_unlock(dev);
if (ret)
goto err_uninit_notify;
@@ -10985,7 +10987,9 @@ void netdev_run_todo(void)
continue;
}
+ netdev_lock(dev);
WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERED);
+ netdev_unlock(dev);
linkwatch_sync_dev(dev);
}
@@ -11591,7 +11595,9 @@ void unregister_netdevice_many_notify(struct list_head *head,
list_for_each_entry(dev, head, unreg_list) {
/* And unlink it from device chain. */
unlist_netdevice(dev);
+ netdev_lock(dev);
WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERING);
+ netdev_unlock(dev);
}
flush_all_backlogs();
