Re: [PATCH net-next v2] net: convert netdev_nl_sock bindings list to xarray

[Jakub Kicinski]

On Tue, 11 Aug 2026 14:29:39 +0000 Shivaji Kant wrote:
> netdev_nl_sock previously used a struct list_head bindings to keep
> track of active netdev netlink bindings, protected by a per-socket
> struct mutex lock (priv->lock).
> 
> Since list modifications and iterations are not concurrency-safe,
> priv->lock was introduced to serialize operations on priv->bindings.
> However, xarray manages its own internal locking (xa_lock) for store,
> erase, and iteration operations.
> 
> Convert bindings in struct netdev_nl_sock from struct list_head to
> struct xarray and remove priv->lock. This simplifies the code by
> removing explicit mutex locking in netdev_nl_bind_rx_doit(),
> netdev_nl_bind_tx_doit(), and socket initialization/teardown functions.

I don't think this is worth touching if you're just trying to simplify
the code. The mutex is in struct netdev_nl_sock, which is meant for all
netdev socket state. It took us a bit of massaging to get the locking
into shape, I think that keeping the mutex around can serve as a more
generic blueprint for others who need to add state to the struct?

Clashiko also doesn't believe in the correctness, I'll send out the
review separately. I didn't look closely but the usual workaround
for store issues, off the top of my head, is to store NULL first,
then swap it for the real value. The store can only fail if the xarray
needs to alloc memory, swap does not fail. I could be wrong tho.