[PATCH] net: core: provide devm_register_netdev()

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Create a new source file for networking devres helpers and provide
devm_register_netdev() - a managed variant of register_netdev().

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
I'm writing a new ethernet driver and I realized there's no devres
variant for register_netdev(). Since this is the only function I need
to get rid of the remove() callback, I thought I'll just go ahead and
add it and send it even before the driver to make it available to other
drivers.

 .../driver-api/driver-model/devres.rst        |  3 ++
 include/linux/netdevice.h                     |  1 +
 net/core/Makefile                             |  2 +-
 net/core/devres.c                             | 41 +++++++++++++++++++
 4 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 net/core/devres.c

diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
index 46c13780994c..11a03b65196e 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -372,6 +372,9 @@ MUX
   devm_mux_chip_register()
   devm_mux_control_get()
 
+NET
+  devm_register_netdev()
+
 PER-CPU MEM
   devm_alloc_percpu()
   devm_free_percpu()
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6c3f7032e8d9..710a7bcfc3dc 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4196,6 +4196,7 @@ 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 device *dev, struct net_device *ndev);
 void unregister_netdev(struct net_device *dev);
 
 /* General hardware address lists handling functions */
diff --git a/net/core/Makefile b/net/core/Makefile
index 3e2c378e5f31..f530894068d2 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -8,7 +8,7 @@ obj-y := sock.o request_sock.o skbuff.o datagram.o stream.o scm.o \
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
 
-obj-y		     += dev.o dev_addr_lists.o dst.o netevent.o \
+obj-y		     += dev.o devres.o dev_addr_lists.o dst.o netevent.o \
 			neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
 			sock_diag.o dev_ioctl.o tso.o sock_reuseport.o \
 			fib_notifier.o xdp.o flow_offload.o
diff --git a/net/core/devres.c b/net/core/devres.c
new file mode 100644
index 000000000000..3c080abd1935
--- /dev/null
+++ b/net/core/devres.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 BayLibre SAS
+ * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ */
+
+#include <linux/device.h>
+#include <linux/netdevice.h>
+
+struct netdevice_devres {
+	struct net_device *ndev;
+};
+
+static void devm_netdev_release(struct device *dev, void *res)
+{
+	struct netdevice_devres *this = res;
+
+	unregister_netdev(this->ndev);
+}
+
+int devm_register_netdev(struct device *dev, struct net_device *ndev)
+{
+	struct netdevice_devres *devres;
+	int ret;
+
+	devres = devres_alloc(devm_netdev_release, sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	ret = register_netdev(ndev);
+	if (ret) {
+		devres_free(devres);
+		return ret;
+	}
+
+	devres->ndev = ndev;
+	devres_add(dev, devres);
+
+	return 0;
+}
+EXPORT_SYMBOL(devm_register_netdev);
-- 
2.25.0