Re: [PATCH net-next] net: run netdev work under the ops-compat lock

On 9/4/26 8:00 PM, Jakub Kicinski wrote:

netdev_work_proc() took rtnl_lock() for the whole batch, forcing
even ops-locked drivers onto rtnl just to run their rx_mode / ndo_work
callbacks. Take the per-device ops-compat lock instead: the instance
lock for ops-locked drivers, rtnl_lock for the rest. That's what the
callbacks already assert (e.g. netif_rx_mode_run() asserts
netdev_assert_locked_ops_compat()), and non-ops-locked work
such as vlan ndo_work keeps rtnl, since its compat lock resolves
to rtnl anyway.

Without this adding more uses of ndo_work, for cases which don't
need rtnl_lock feels like a step back.

We can drop the comment about the extra ref now, with the relocking
it's a necessity.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Dump question: can the `netdev_work_list` work list grow significantly
under non pathological conditions? netdev_work_proc is now going to
acquire and release the rtnl lock n-times for non ops-enabled drivers.

Would it be overkill trying to acquire the rtnl lock at most once (i.e.
keeping the netdev_need_ops_lock() and legacy drivers on separate list
and process them accordingly?)

/P