net: Allow changing number of RX queues after device allocation

For RPS, we create a kobject for each RX queue based on the number of
queues passed to alloc_netdev_mq().  However, drivers generally do not
determine the numbers of hardware queues to use until much later, so
this usually represents the maximum number the driver may use and not
the actual number in use.

For TX queues, drivers can update the actual number using
netif_set_real_num_tx_queues().  Add a corresponding function for RX
queues, netif_set_real_num_rx_queues().

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 14 deletions

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 76485a3f910b..fa81fd0a488f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -742,34 +742,38 @@ static int rx_queue_add_kobject(struct net_device *net, int index)
         return error;
 }
 
-static int rx_queue_register_kobjects(struct net_device *net)
+int
+net_rx_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
 {
         int i;
         int error = 0;
 
-        net->queues_kset = kset_create_and_add("queues",
-            NULL, &net->dev.kobj);
-        if (!net->queues_kset)
-                return -ENOMEM;
-        for (i = 0; i < net->num_rx_queues; i++) {
+        for (i = old_num; i < new_num; i++) {
                 error = rx_queue_add_kobject(net, i);
-                if (error)
+                if (error) {
+                        new_num = old_num;
                         break;
+                }
         }
 
-        if (error)
-                while (--i >= 0)
-                        kobject_put(&net->_rx[i].kobj);
+        while (--i >= new_num)
+                kobject_put(&net->_rx[i].kobj);
 
         return error;
 }
 
-static void rx_queue_remove_kobjects(struct net_device *net)
+static int rx_queue_register_kobjects(struct net_device *net)
 {
-        int i;
+        net->queues_kset = kset_create_and_add("queues",
+            NULL, &net->dev.kobj);
+        if (!net->queues_kset)
+                return -ENOMEM;
+        return net_rx_queue_update_kobjects(net, 0, net->real_num_rx_queues);
+}
 
-        for (i = 0; i < net->num_rx_queues; i++)
-                kobject_put(&net->_rx[i].kobj);
+static void rx_queue_remove_kobjects(struct net_device *net)
+{
+        net_rx_queue_update_kobjects(net, net->real_num_rx_queues, 0);
         kset_unregister(net->queues_kset);
 }
 #endif /* CONFIG_RPS */