net: avoid nul-deref trying to bind mp to incapable device

net: avoid nul-deref trying to bind mp to incapable device

Sashiko points out that we use qops in __net_mp_open_rxq()
but never validate they are null. This was introduced when
check was moved from netdev_rx_queue_restart().

Look at ops directly instead of the locking config.
qops imply netdev_need_ops_lock(). We used netdev_need_ops_lock()
initially to signify that the real_num_rx_queues check below
is safe without rtnl_lock, but I'm not sure if this is actually
clear to most people, anyway.

Fixes: da7772a2b4ad ("net: move mp->rx_page_size validation to __net_mp_open_rxq()")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20260404001938.2425670-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>