Re: [PATCH net-next v1 0/2] Reuse threaded NAPI kthread across napi_del()/napi_add().

[Jakub Kicinski <kuba@kernel.org>]

On Mon, 29 Jun 2026 12:20:25 -0700 Shuhao Tan wrote:
> These drivers destroy and recreate queues during configuration
> changes. If a NAPI was threaded before destruction, during the
> creation, a new kthread will be spawned for the NAPI.
> 
> Some drivers do not have this problem, e.g. netdevsim. But these
> drivers and the drivers mentioned above will still lose kthread
> during link flap (ndo_stop/ndo_open).
> 
> Because the kthreads before and after these configuration changes are
> different, all the attributes associated with the kthread are lost.
> These include CPU mask, priority, scheduler policy, etc.. If the
> threaded state is preserved for a NAPI, it makes sense to want to
> preserve the attributes of the thread as well.

Send a netdev Netlink notification when NAPI is re-created and
let the userspace re-apply the settings? Keeping a few u32s
around is one thing but keeping a thread running and visible
in /procfs for the lifetime of a machine feels a little bit much.
IDK.