net: Simplify RX queue allocation

This patch move RX queue allocation to alloc_netdev_mq and freeing of
the queues to free_netdev (symmetric to TX queue allocation).  Each
kobject RX queue takes a reference to the queue's device so that the
device can't be freed before all the kobjects have been released-- this
obviates the need for reference counts specific to RX queues.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 13 insertions, 16 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6e4cfbc53d4c..fccb11f879e5 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -592,8 +592,7 @@ struct netdev_rx_queue {
         struct rps_map __rcu            *rps_map;
         struct rps_dev_flow_table __rcu *rps_flow_table;
         struct kobject                  kobj;
-        struct netdev_rx_queue          *first;
-        atomic_t                        count;
+        struct net_device               *dev;
 } ____cacheline_aligned_in_smp;
 #endif /* CONFIG_RPS */
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 75490670e0a9..8725d168d1f5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5051,12 +5051,8 @@ static int netif_alloc_rx_queues(struct net_device *dev)
         }
         dev->_rx = rx;
 
-        /*
-         * Set a pointer to first element in the array which holds the
-         * reference count.
-         */
         for (i = 0; i < count; i++)
-                rx[i].first = rx;
+                rx[i].dev = dev;
 #endif
         return 0;
 }
@@ -5132,10 +5128,6 @@ int register_netdevice(struct net_device *dev)
 
         dev->iflink = -1;
 
-        ret = netif_alloc_rx_queues(dev);
-        if (ret)
-                goto out;
-
         netdev_init_queues(dev);
 
         /* Init, if this function is available */
@@ -5601,6 +5593,8 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
 #ifdef CONFIG_RPS
         dev->num_rx_queues = queue_count;
         dev->real_num_rx_queues = queue_count;
+        if (netif_alloc_rx_queues(dev))
+                goto free_pcpu;
 #endif
 
         dev->gso_max_size = GSO_MAX_SIZE;
@@ -5618,6 +5612,10 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
 free_pcpu:
         free_percpu(dev->pcpu_refcnt);
         kfree(dev->_tx);
+#ifdef CONFIG_RPS
+        kfree(dev->_rx);
+#endif
+
 free_p:
         kfree(p);
         return NULL;
@@ -5639,6 +5637,9 @@ void free_netdev(struct net_device *dev)
         release_net(dev_net(dev));
 
         kfree(dev->_tx);
+#ifdef CONFIG_RPS
+        kfree(dev->_rx);
+#endif
 
         kfree(rcu_dereference_raw(dev->ingress_queue));
 
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index a5ff5a89f376..3ba526b56fe3 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -706,7 +706,6 @@ static struct attribute *rx_queue_default_attrs[] = {
 static void rx_queue_release(struct kobject *kobj)
 {
         struct netdev_rx_queue *queue = to_rx_queue(kobj);
-        struct netdev_rx_queue *first = queue->first;
         struct rps_map *map;
         struct rps_dev_flow_table *flow_table;
 
@@ -719,8 +718,7 @@ static void rx_queue_release(struct kobject *kobj)
         if (flow_table)
                 call_rcu(&flow_table->rcu, rps_dev_flow_table_release);
 
-        if (atomic_dec_and_test(&first->count))
-                kfree(first);
+        dev_put(queue->dev);
 }
 
 static struct kobj_type rx_queue_ktype = {
@@ -732,7 +730,6 @@ static struct kobj_type rx_queue_ktype = {
 static int rx_queue_add_kobject(struct net_device *net, int index)
 {
         struct netdev_rx_queue *queue = net->_rx + index;
-        struct netdev_rx_queue *first = queue->first;
         struct kobject *kobj = &queue->kobj;
         int error = 0;
 
@@ -745,7 +742,7 @@ static int rx_queue_add_kobject(struct net_device *net, int index)
         }
 
         kobject_uevent(kobj, KOBJ_ADD);
-        atomic_inc(&first->count);
+        dev_hold(queue->dev);
 
         return error;
 }