On Mon, Jan 27, 2025 at 01:37:56PM -0800, Jakub Kicinski wrote:

On Tue, 21 Jan 2025 19:10:41 +0000 Joe Damato wrote:

quoted

From: Jakub Kicinski <kuba@kernel.org>

netdev netlink is the only reader of netdev_{,rx_}queue->napi,
and it already holds netdev->lock. Switch protection of the
writes to netdev->lock as well.

Add netif_queue_set_napi_locked() for API completeness,
but the expectation is that most current drivers won't have
to worry about locking any more. Today they jump thru hoops
to take rtnl_lock.

I started having second thoughts about this patch, sorry to say.
NAPI objects were easy to protect with the lock because there's
a clear registration and unregistration API. Queues OTOH are made
visible by the netif_set_real_num_queues() call, which is tricky 
to protect with the instance lock. Queues are made visible, then
we configure them.

My thinking changed a bit, I think we should aim to protect all
ndos and ethtool ops with the instance lock. Stanislav and Saeed
seem to be working on that:
https://lore.kernel.org/all/Z5LhKdNMO5CvAvZf@mini-arch/ (local)
so hopefully that doesn't cause too much of a delay.
But you may need to rework this series further :(

OK, I'll wait for something to emerge from that work before
re-spinning this.