net: Add support for XPS without sysfs being defined

This patch makes it so that we can support transmit packet steering without
sysfs needing to be enabled.  The reason for making this change is to make
it so that a driver can make use of the XPS even while the sysfs portion of
the interface is not present.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2104,7 +2104,6 @@ static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
 }
 
 #ifdef CONFIG_XPS
-extern void netif_reset_xps_queue(struct net_device *dev, u16 index);
 extern int netif_set_xps_queue(struct net_device *dev, struct cpumask *mask,
 			       u16 index);
 #else

net/Kconfig

@@ -232,7 +232,7 @@ config RFS_ACCEL
 
 config XPS
 	boolean
-	depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS
+	depends on SMP && USE_GENERIC_SMP_HELPERS
 	default y
 
 config NETPRIO_CGROUP

net/core/dev.c

@@ -1887,10 +1887,10 @@ static struct xps_map *remove_xps_queue(struct xps_dev_maps *dev_maps,
 	return map;
 }
 
-void netif_reset_xps_queue(struct net_device *dev, u16 index)
+static void netif_reset_xps_queues_gt(struct net_device *dev, u16 index)
 {
 	struct xps_dev_maps *dev_maps;
-	int cpu;
+	int cpu, i;
 	bool active = false;
 
 	mutex_lock(&xps_map_mutex);
@@ -1900,7 +1900,11 @@ void netif_reset_xps_queue(struct net_device *dev, u16 index)
 		goto out_no_maps;
 
 	for_each_possible_cpu(cpu) {
-		if (remove_xps_queue(dev_maps, cpu, index))
+		for (i = index; i < dev->num_tx_queues; i++) {
+			if (!remove_xps_queue(dev_maps, cpu, i))
+				break;
+		}
+		if (i == dev->num_tx_queues)
 			active = true;
 	}
 
@@ -1909,8 +1913,10 @@ void netif_reset_xps_queue(struct net_device *dev, u16 index)
 		kfree_rcu(dev_maps, rcu);
 	}
 
-	netdev_queue_numa_node_write(netdev_get_tx_queue(dev, index),
+	for (i = index; i < dev->num_tx_queues; i++)
+		netdev_queue_numa_node_write(netdev_get_tx_queue(dev, i),
 					     NUMA_NO_NODE);
+
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
 }
@@ -2096,8 +2102,12 @@ int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
 		if (dev->num_tc)
 			netif_setup_tc(dev, txq);
 
-		if (txq < dev->real_num_tx_queues)
+		if (txq < dev->real_num_tx_queues) {
 			qdisc_reset_all_tx_gt(dev, txq);
+#ifdef CONFIG_XPS
+			netif_reset_xps_queues_gt(dev, txq);
+#endif
+		}
 	}
 
 	dev->real_num_tx_queues = txq;
@@ -5919,6 +5929,10 @@ static void rollback_registered_many(struct list_head *head)
 
 		/* Remove entries from kobject tree */
 		netdev_unregister_kobject(dev);
+#ifdef CONFIG_XPS
+		/* Remove XPS queueing entries */
+		netif_reset_xps_queues_gt(dev, 0);
+#endif
 	}
 
 	synchronize_net();

net/core/net-sysfs.c

@@ -1002,16 +1002,6 @@ static ssize_t show_xps_map(struct netdev_queue *queue,
 	return len;
 }
 
-static void xps_queue_release(struct netdev_queue *queue)
-{
-	struct net_device *dev = queue->dev;
-	unsigned long index;
-
-	index = get_netdev_queue_index(queue);
-
-	netif_reset_xps_queue(dev, index);
-}
-
 static ssize_t store_xps_map(struct netdev_queue *queue,
 		      struct netdev_queue_attribute *attribute,
 		      const char *buf, size_t len)
@@ -1058,10 +1048,6 @@ static void netdev_queue_release(struct kobject *kobj)
 {
 	struct netdev_queue *queue = to_netdev_queue(kobj);
 
-#ifdef CONFIG_XPS
-	xps_queue_release(queue);
-#endif
-
 	memset(kobj, 0, sizeof(*kobj));
 	dev_put(queue->dev);
 }