From: Jakub Kicinski <kuba@kernel.org>
To: Jiri Pirko <jiri@resnulli.us>
Cc: netdev@vger.kernel.org, pabeni@redhat.com, davem@davemloft.net,
edumazet@google.com, jacob.e.keller@intel.com, saeedm@nvidia.com,
moshe@nvidia.com
Subject: Re: [patch net 3/3] devlink: fix a deadlock with nested instances during namespace remove
Date: Tue, 9 May 2023 20:24:44 -0700 [thread overview]
Message-ID: <20230509202444.30436b9f@kernel.org> (raw)
In-Reply-To: <20230509100939.760867-1-jiri@resnulli.us>
On Tue, 9 May 2023 12:09:36 +0200 Jiri Pirko wrote:
> The commit 565b4824c39f ("devlink: change port event netdev notifier
> from per-net to global") changed original per-net notifier to be global
> which fixed the issue of non-receiving events of netdev uninit if that
> moved to a different namespace. That worked fine in -net tree.
>
> However, later on when commit ee75f1fc44dd ("net/mlx5e: Create
> separate devlink instance for ethernet auxiliary device") and
> commit 72ed5d5624af ("net/mlx5: Suspend auxiliary devices only in
> case of PCI device suspend") were merged, a deadlock was introduced
> when removing a namespace with devlink instance with another nested
> instance.
>
> Here there is the bad flow example resulting in deadlock with mlx5:
> net_cleanup_work -> cleanup_net (takes down_read(&pernet_ops_rwsem) ->
> devlink_pernet_pre_exit() -> devlink_reload() ->
> mlx5_devlink_reload_down() -> mlx5_unload_one_devl_locked() ->
> mlx5_detach_device() -> del_adev() -> mlx5e_remove() ->
> mlx5e_destroy_devlink() -> devlink_free() ->
> unregister_netdevice_notifier() (takes down_write(&pernet_ops_rwsem)
Why don't we have a single, static notifier for all of devlink?
Why the per device/per port notifiers?
We have the devlink port pointer in struct net_device, resolving from
a global event to the correct devlink instance is trivial.
next prev parent reply other threads:[~2023-05-10 3:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-09 10:09 [patch net 3/3] devlink: fix a deadlock with nested instances during namespace remove Jiri Pirko
2023-05-09 10:09 ` [patch net 1/3] net: allow to ask per-net netdevice notifier to follow netdev dynamically Jiri Pirko
2023-05-09 10:09 ` [patch net 2/3] devlink: make netdev notifier per-port Jiri Pirko
2023-05-09 10:09 ` [patch net 3/3] devlink: change port event netdev notifier to be per-net and following netdev Jiri Pirko
2023-05-09 20:13 ` [patch net 3/3] devlink: fix a deadlock with nested instances during namespace remove Jacob Keller
2023-05-10 3:24 ` Jakub Kicinski [this message]
2023-05-10 6:11 ` Jiri Pirko
2023-05-10 18:27 ` Jacob Keller
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