net sched: use xps information for qdisc NUMA affinity

Allocate qdisc memory according to NUMA properties of cpus included in
xps map.

To be effective, qdisc should be (re)setup after changes
of /sys/class/net/eth<n>/queues/tx-<n>/xps_cpus

I added a numa_node field in struct netdev_queue, containing NUMA node
if all cpus included in xps_cpus share same node, else -1.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_generic.c

@@ -553,7 +553,9 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 	size = QDISC_ALIGN(sizeof(*sch));
 	size += ops->priv_size + (QDISC_ALIGNTO - 1);
 
-	p = kzalloc(size, GFP_KERNEL);
+	p = kzalloc_node(size, GFP_KERNEL,
+			 netdev_queue_numa_node_read(dev_queue));
+
 	if (!p)
 		goto errout;
 	sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);