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>
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index f85cee3..85e8b53 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -913,6 +913,7 @@
 	struct xps_map *map, *new_map;
 	struct xps_dev_maps *dev_maps, *new_dev_maps;
 	int nonempty = 0;
+	int numa_node = -2;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
@@ -953,7 +954,14 @@
 			pos = map_len = alloc_len = 0;
 
 		need_set = cpu_isset(cpu, *mask) && cpu_online(cpu);
-
+#ifdef CONFIG_NUMA
+		if (need_set) {
+			if (numa_node == -2)
+				numa_node = cpu_to_node(cpu);
+			else if (numa_node != cpu_to_node(cpu))
+				numa_node = -1;
+		}
+#endif
 		if (need_set && pos >= map_len) {
 			/* Need to add queue to this CPU's map */
 			if (map_len >= alloc_len) {
@@ -1001,6 +1009,8 @@
 	if (dev_maps)
 		call_rcu(&dev_maps->rcu, xps_dev_maps_release);
 
+	netdev_queue_numa_node_write(queue, (numa_node >= 0) ? numa_node : -1);
+
 	mutex_unlock(&xps_map_mutex);
 
 	free_cpumask_var(mask);