s390/qeth: allow configuration of TX queues for IQD devices
Similar to the support for z/VM NICs, but we need to take extra care
about the dedicated mcast queue:
1. netdev_pick_tx() is unaware of this limitation and might select the
mcast txq. Catch this.
2. require at least _two_ TX queues - one for ucast, one for mcast.
3. when reducing the number of TX queues, there's a potential race
where netdev_cap_txqueue() over-rules the selected txq index and
falls back to index 0. This would place ucast traffic on the mcast
queue, and result in TX errors.
So for IQD, reject a reduction while the interface is running.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2 files changed