[PATCH 05/11] net: core: provide devm_register_netdev()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszew...@baylibre.com>

Provide devm_register_netdev() - a device resource managed variant
of register_netdev(). This new helper will only work for net_device
structs that have a parent device assigned and are devres managed too.

Signed-off-by: Bartosz Golaszewski <bgolaszew...@baylibre.com>
---
 include/linux/netdevice.h |  4 ++++
 net/core/dev.c            | 48 +++++++++++++++++++++++++++++++++++++++
 net/ethernet/eth.c        |  1 +
 3 files changed, 53 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 130a668049ab..433bd5ca2efc 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1515,6 +1515,8 @@ struct net_device_ops {
  * @IFF_FAILOVER_SLAVE: device is lower dev of a failover master device
  * @IFF_L3MDEV_RX_HANDLER: only invoke the rx handler of L3 master device
  * @IFF_LIVE_RENAME_OK: rename is allowed while device is up and running
+ * @IFF_IS_DEVRES: this structure was allocated dynamically and is managed by
+ *     devres
  */
 enum netdev_priv_flags {
        IFF_802_1Q_VLAN                 = 1<<0,
@@ -1548,6 +1550,7 @@ enum netdev_priv_flags {
        IFF_FAILOVER_SLAVE              = 1<<28,
        IFF_L3MDEV_RX_HANDLER           = 1<<29,
        IFF_LIVE_RENAME_OK              = 1<<30,
+       IFF_IS_DEVRES                   = 1<<31,
 };
 
 #define IFF_802_1Q_VLAN                        IFF_802_1Q_VLAN
@@ -4206,6 +4209,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, 
const char *name,
                         count)
 
 int register_netdev(struct net_device *dev);
+int devm_register_netdev(struct net_device *ndev);
 void unregister_netdev(struct net_device *dev);
 
 /* General hardware address lists handling functions */
diff --git a/net/core/dev.c b/net/core/dev.c
index 522288177bbd..99db537c9468 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9519,6 +9519,54 @@ int register_netdev(struct net_device *dev)
 }
 EXPORT_SYMBOL(register_netdev);
 
+struct netdevice_devres {
+       struct net_device *ndev;
+};
+
+static void devm_netdev_release(struct device *dev, void *this)
+{
+       struct netdevice_devres *res = this;
+
+       unregister_netdev(res->ndev);
+}
+
+/**
+ *     devm_register_netdev - resource managed variant of register_netdev()
+ *     @ndev: device to register
+ *
+ *     This is a devres variant of register_netdev() for which the unregister
+ *     function will be call automatically when the parent device of ndev
+ *     is detached.
+ */
+int devm_register_netdev(struct net_device *ndev)
+{
+       struct netdevice_devres *dr;
+       int ret;
+
+       /* struct net_device itself must be devres managed. */
+       BUG_ON(!(ndev->priv_flags & IFF_IS_DEVRES));
+       /* struct net_device must have a parent device - it will be the device
+        * managing this resource.
+        */
+       BUG_ON(!ndev->dev.parent);
+
+       dr = devres_alloc(devm_netdev_release, sizeof(*dr), GFP_KERNEL);
+       if (!dr)
+               return -ENOMEM;
+
+       ret = register_netdev(ndev);
+       if (ret) {
+               devres_free(dr);
+               return ret;
+       }
+
+       dr->ndev = ndev;
+       devres_add(ndev->dev.parent, dr);
+
+       return 0;
+}
+EXPORT_SYMBOL(devm_register_netdev);
+
 int netdev_refcnt_read(const struct net_device *dev)
 {
        int i, refcnt = 0;
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index c8b903302ff2..ce9b5e576f20 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -423,6 +423,7 @@ struct net_device *devm_alloc_etherdev_mqs(struct device 
*dev, int sizeof_priv,
 
        *dr = netdev;
        devres_add(dev, dr);
+       netdev->priv_flags |= IFF_IS_DEVRES;
 
        return netdev;
 }
-- 
2.25.0