From: Jakub Kicinski <kuba@kernel.org>

netdev_config manipulation will become slightly more complicated
soon and we will need to call if from ethtool as well as queue API.
Encapsulate the logic into helper functions.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 net/core/Makefile        |  2 +-
 net/core/dev.c           |  7 ++-----
 net/core/dev.h           |  5 +++++
 net/core/netdev_config.c | 43 ++++++++++++++++++++++++++++++++++++++++
 net/ethtool/netlink.c    | 14 ++++++-------
 5 files changed, 57 insertions(+), 14 deletions(-)
 create mode 100644 net/core/netdev_config.c

diff --git a/net/core/Makefile b/net/core/Makefile
index b2a76ce33932..4db487396094 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile

@@ -19,7 +19,7 @@ obj-$(CONFIG_NETDEV_ADDR_LIST_TEST) += dev_addr_lists_test.o

 obj-y += net-sysfs.o
 obj-y += hotdata.o
-obj-y += netdev_rx_queue.o
+obj-y += netdev_config.o netdev_rx_queue.o
 obj-$(CONFIG_PAGE_POOL) += page_pool.o page_pool_user.o
 obj-$(CONFIG_PROC_FS) += net-procfs.o
 obj-$(CONFIG_NET_PKTGEN) += pktgen.o

diff --git a/net/core/dev.c b/net/core/dev.c
index 5a3c0f40a93f..7cd4e5eab441 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c

@@ -11873,10 +11873,8 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
        if (!dev->ethtool)
                goto free_all;

-       dev->cfg = kzalloc(sizeof(*dev->cfg), GFP_KERNEL_ACCOUNT);
-       if (!dev->cfg)
+       if (netdev_alloc_config(dev))
                goto free_all;
-       dev->cfg_pending = dev->cfg;

        dev->num_napi_configs = maxqs;
        napi_config_sz = array_size(maxqs, sizeof(*dev->napi_config));

@@ -11947,8 +11945,7 @@ void free_netdev(struct net_device *dev)
                return;
        }

-       WARN_ON(dev->cfg != dev->cfg_pending);
-       kfree(dev->cfg);
+       netdev_free_config(dev);
        kfree(dev->ethtool);
        netif_free_tx_queues(dev);
        netif_free_rx_queues(dev);

diff --git a/net/core/dev.h b/net/core/dev.h
index d6b08d435479..7041c8bd2a0f 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h

@@ -92,6 +92,11 @@ extern struct rw_semaphore dev_addr_sem;
 extern struct list_head net_todo_list;
 void netdev_run_todo(void);

+int netdev_alloc_config(struct net_device *dev);
+void __netdev_free_config(struct netdev_config *cfg);
+void netdev_free_config(struct net_device *dev);
+int netdev_reconfig_start(struct net_device *dev);
+
 /* netdev management, shared between various uAPI entry points */
 struct netdev_name_node {
        struct hlist_node hlist;

diff --git a/net/core/netdev_config.c b/net/core/netdev_config.c
new file mode 100644
index 000000000000..270b7f10a192
--- /dev/null
+++ b/net/core/netdev_config.c

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/netdevice.h>
+#include <net/netdev_queues.h>
+
+#include "dev.h"
+
+int netdev_alloc_config(struct net_device *dev)
+{
+       struct netdev_config *cfg;
+
+       cfg = kzalloc(sizeof(*dev->cfg), GFP_KERNEL_ACCOUNT);
+       if (!cfg)
+               return -ENOMEM;
+
+       dev->cfg = cfg;
+       dev->cfg_pending = cfg;
+       return 0;
+}
+
+void __netdev_free_config(struct netdev_config *cfg)
+{
+       kfree(cfg);
+}
+
+void netdev_free_config(struct net_device *dev)
+{
+       WARN_ON(dev->cfg != dev->cfg_pending);
+       __netdev_free_config(dev->cfg);
+}
+
+int netdev_reconfig_start(struct net_device *dev)
+{
+       struct netdev_config *cfg;
+
+       WARN_ON(dev->cfg != dev->cfg_pending);
+       cfg = kmemdup(dev->cfg, sizeof(*dev->cfg), GFP_KERNEL_ACCOUNT);
+       if (!cfg)
+               return -ENOMEM;
+
+       dev->cfg_pending = cfg;
+       return 0;