Messages in this thread | | | Date | Tue, 9 Nov 2021 16:12:33 +0200 | From | Leon Romanovsky <> | Subject | Re: [PATCH net-next] devlink: Require devlink lock during device reload |
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On Mon, Nov 08, 2021 at 03:31:26PM -0800, Jakub Kicinski wrote: > On Mon, 8 Nov 2021 21:58:36 +0200 Leon Romanovsky wrote: > > > > > nfp will benefit from the simplified locking as well, and so will bnxt, > > > > > although I'm not sure the maintainers will opt for using devlink framework > > > > > due to the downstream requirements. > > > > > > > > Exactly why devlink should be fixed first. > > > > > > If by "fixed first" you mean it needs 5 locks to be added and to remove > > > any guarantees on sub-object lifetime then no thanks. > > > > How do you plan to fix pernet_ops_rwsem lock? By exposing devlink state > > to the drivers? By providing unlocked version of unregister_netdevice_notifier? > > > > This simple scenario has deadlocks: > > sudo ip netns add n1 > > sudo devlink dev reload pci/0000:00:09.0 netns n1 > > sudo ip netns del n1 > > Okay - I'm not sure why you're asking me this. This is not related to > devlink locking as far as I can tell. Neither are you fixing this > problem in your own RFC.
I asked you because you clearly showed to me that things that makes sense for me, doesn't make sense for you and vice versa.
I don't want to do work that will be thrown away.
> > You'd need to tell me more about what the notifier is used for (I see > RoCE in the call trace). I don't understand why you need to re-register > a global (i.e. not per netns) notifier when devlink is switching name > spaces.
RDMA subsystem supports two net namespace aware scenarios.
We need global netdev_notifier for shared mode. This is legacy mode where we listen to all namespaces. We must support this mode otherwise we break whole RDMA world.
See commit below: de641d74fb00 ("Revert "RDMA/mlx5: Fix devlink deadlock on net namespace deletion"")
Thanks
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