net: Add functions netif_reset_xps_queue and netif_set_xps_queue

This patch adds two functions, netif_reset_xps_queue and
netif_set_xps_queue.  The main idea behind these two functions is to
provide a mechanism through which drivers can update their defaults in
regards to XPS.

Currently no such mechanism exists and as a result we cannot use XPS for
things such as ATR which would require a basic configuration to start in
which the Tx queues are mapped to CPUs via a 1:1 mapping.  With this change
I am making it possible for drivers such as ixgbe to be able to use the XPS
feature by controlling the default configuration.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 143 deletions

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 29c884a74c38..5ad489d5d062 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1002,54 +1002,14 @@ static ssize_t show_xps_map(struct netdev_queue *queue,
 	return len;
 }
 
-static DEFINE_MUTEX(xps_map_mutex);
-#define xmap_dereference(P)		\
-	rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
-
 static void xps_queue_release(struct netdev_queue *queue)
 {
 	struct net_device *dev = queue->dev;
-	struct xps_dev_maps *dev_maps;
-	struct xps_map *map;
 	unsigned long index;
-	int i, pos, nonempty = 0;
 
 	index = get_netdev_queue_index(queue);
 
-	mutex_lock(&xps_map_mutex);
-	dev_maps = xmap_dereference(dev->xps_maps);
-
-	if (dev_maps) {
-		for_each_possible_cpu(i) {
-			map = xmap_dereference(dev_maps->cpu_map[i]);
-			if (!map)
-				continue;
-
-			for (pos = 0; pos < map->len; pos++)
-				if (map->queues[pos] == index)
-					break;
-
-			if (pos < map->len) {
-				if (map->len > 1)
-					map->queues[pos] =
-					    map->queues[--map->len];
-				else {
-					RCU_INIT_POINTER(dev_maps->cpu_map[i],
-					    NULL);
-					kfree_rcu(map, rcu);
-					map = NULL;
-				}
-			}
-			if (map)
-				nonempty = 1;
-		}
-
-		if (!nonempty) {
-			RCU_INIT_POINTER(dev->xps_maps, NULL);
-			kfree_rcu(dev_maps, rcu);
-		}
-	}
-	mutex_unlock(&xps_map_mutex);
+	netif_reset_xps_queue(dev, index);
 }
 
 static ssize_t store_xps_map(struct netdev_queue *queue,
@@ -1057,13 +1017,9 @@ static ssize_t store_xps_map(struct netdev_queue *queue,
 		      const char *buf, size_t len)
 {
 	struct net_device *dev = queue->dev;
-	cpumask_var_t mask;
-	int err, i, cpu, pos, map_len, alloc_len, need_set;
 	unsigned long index;
-	struct xps_map *map, *new_map;
-	struct xps_dev_maps *dev_maps, *new_dev_maps;
-	int nonempty = 0;
-	int numa_node_id = -2;
+	cpumask_var_t mask;
+	int err;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
@@ -1079,105 +1035,11 @@ static ssize_t store_xps_map(struct netdev_queue *queue,
 		return err;
 	}
 
-	new_dev_maps = kzalloc(max_t(unsigned int,
-	    XPS_DEV_MAPS_SIZE, L1_CACHE_BYTES), GFP_KERNEL);
-	if (!new_dev_maps) {
-		free_cpumask_var(mask);
-		return -ENOMEM;
-	}
-
-	mutex_lock(&xps_map_mutex);
-
-	dev_maps = xmap_dereference(dev->xps_maps);
-
-	for_each_possible_cpu(cpu) {
-		map = dev_maps ?
-			xmap_dereference(dev_maps->cpu_map[cpu]) : NULL;
-		new_map = map;
-		if (map) {
-			for (pos = 0; pos < map->len; pos++)
-				if (map->queues[pos] == index)
-					break;
-			map_len = map->len;
-			alloc_len = map->alloc_len;
-		} else
-			pos = map_len = alloc_len = 0;
-
-		need_set = cpumask_test_cpu(cpu, mask) && cpu_online(cpu);
-#ifdef CONFIG_NUMA
-		if (need_set) {
-			if (numa_node_id == -2)
-				numa_node_id = cpu_to_node(cpu);
-			else if (numa_node_id != cpu_to_node(cpu))
-				numa_node_id = -1;
-		}
-#endif
-		if (need_set && pos >= map_len) {
-			/* Need to add queue to this CPU's map */
-			if (map_len >= alloc_len) {
-				alloc_len = alloc_len ?
-				    2 * alloc_len : XPS_MIN_MAP_ALLOC;
-				new_map = kzalloc_node(XPS_MAP_SIZE(alloc_len),
-						       GFP_KERNEL,
-						       cpu_to_node(cpu));
-				if (!new_map)
-					goto error;
-				new_map->alloc_len = alloc_len;
-				for (i = 0; i < map_len; i++)
-					new_map->queues[i] = map->queues[i];
-				new_map->len = map_len;
-			}
-			new_map->queues[new_map->len++] = index;
-		} else if (!need_set && pos < map_len) {
-			/* Need to remove queue from this CPU's map */
-			if (map_len > 1)
-				new_map->queues[pos] =
-				    new_map->queues[--new_map->len];
-			else
-				new_map = NULL;
-		}
-		RCU_INIT_POINTER(new_dev_maps->cpu_map[cpu], new_map);
-	}
-
-	/* Cleanup old maps */
-	for_each_possible_cpu(cpu) {
-		map = dev_maps ?
-			xmap_dereference(dev_maps->cpu_map[cpu]) : NULL;
-		if (map && xmap_dereference(new_dev_maps->cpu_map[cpu]) != map)
-			kfree_rcu(map, rcu);
-		if (new_dev_maps->cpu_map[cpu])
-			nonempty = 1;
-	}
-
-	if (nonempty) {
-		rcu_assign_pointer(dev->xps_maps, new_dev_maps);
-	} else {
-		kfree(new_dev_maps);
-		RCU_INIT_POINTER(dev->xps_maps, NULL);
-	}
-
-	if (dev_maps)
-		kfree_rcu(dev_maps, rcu);
-
-	netdev_queue_numa_node_write(queue, (numa_node_id >= 0) ? numa_node_id :
-					    NUMA_NO_NODE);
-
-	mutex_unlock(&xps_map_mutex);
+	err = netif_set_xps_queue(dev, mask, index);
 
 	free_cpumask_var(mask);
-	return len;
 
-error:
-	mutex_unlock(&xps_map_mutex);
-
-	if (new_dev_maps)
-		for_each_possible_cpu(i)
-			kfree(rcu_dereference_protected(
-				new_dev_maps->cpu_map[i],
-				1));
-	kfree(new_dev_maps);
-	free_cpumask_var(mask);
-	return -ENOMEM;
+	return err ? : len;
 }
 
 static struct netdev_queue_attribute xps_cpus_attribute =