[PATCH net-next 07/10] devlink: allow devlink instance allocation without a backing device

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@nvidia.com>

Allow devlink_alloc_ns() to be called with dev=NULL to support
device-less devlink instances. When dev is NULL, the instance is
identified over netlink using "devlink_index" as bus_name and
the decimal index value as dev_name.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
 include/uapi/linux/devlink.h |  2 ++
 net/devlink/core.c           | 26 +++++++++++++++++++++-----
 net/devlink/dev.c            | 11 +++++++----
 net/devlink/devl_internal.h  |  4 ++--
 net/devlink/port.c           | 14 +++++++++-----
 5 files changed, 41 insertions(+), 16 deletions(-)

diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index 1ba3436db4ae..7de2d8cc862f 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -19,6 +19,8 @@
 #define DEVLINK_GENL_VERSION 0x1
 #define DEVLINK_GENL_MCGRP_CONFIG_NAME "config"
 
+#define DEVLINK_INDEX_BUS_NAME "devlink_index"
+
 enum devlink_command {
 	/* don't change the order or add anything between, this is ABI! */
 	DEVLINK_CMD_UNSPEC,
diff --git a/net/devlink/core.c b/net/devlink/core.c
index 85e83a3b082a..9cdda570e584 100644
--- a/net/devlink/core.c
+++ b/net/devlink/core.c
@@ -330,7 +330,10 @@ static void devlink_release(struct work_struct *work)
 
 	mutex_destroy(&devlink->lock);
 	lockdep_unregister_key(&devlink->lock_key);
-	put_device(devlink->dev);
+	if (devlink->dev)
+		put_device(devlink->dev);
+	else
+		kfree(devlink->dev_name);
 	kvfree(devlink);
 }
 
@@ -445,7 +448,7 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
 	static u32 last_id;
 	int ret;
 
-	WARN_ON(!ops || !dev);
+	WARN_ON(!ops);
 	if (!devlink_reload_actions_valid(ops))
 		return NULL;
 
@@ -453,14 +456,22 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
 	if (!devlink)
 		return NULL;
 
+	if (dev) {
+		devlink->dev = get_device(dev);
+		devlink->bus_name = dev->bus->name;
+		devlink->dev_name = dev_name(dev);
+	} else {
+		devlink->bus_name = DEVLINK_INDEX_BUS_NAME;
+		devlink->dev_name = kasprintf(GFP_KERNEL, "%u", devlink->index);
+		if (!devlink->dev_name)
+			goto err_kasprintf;
+	}
+
 	ret = xa_alloc_cyclic(&devlinks, &devlink->index, devlink, xa_limit_31b,
 			      &last_id, GFP_KERNEL);
 	if (ret < 0)
 		goto err_xa_alloc;
 
-	devlink->dev = get_device(dev);
-	devlink->bus_name = dev->bus->name;
-	devlink->dev_name = dev_name(dev);
 	devlink->ops = ops;
 	xa_init_flags(&devlink->ports, XA_FLAGS_ALLOC);
 	xa_init_flags(&devlink->params, XA_FLAGS_ALLOC);
@@ -486,6 +497,11 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
 	return devlink;
 
 err_xa_alloc:
+	if (devlink->dev)
+		put_device(devlink->dev);
+	else
+		kfree(devlink->dev_name);
+err_kasprintf:
 	kvfree(devlink);
 	return NULL;
 }
diff --git a/net/devlink/dev.c b/net/devlink/dev.c
index e3a36de4f4ae..b63597312bbd 100644
--- a/net/devlink/dev.c
+++ b/net/devlink/dev.c
@@ -453,7 +453,8 @@ int devlink_reload(struct devlink *devlink, struct net *dest_net,
 	 * (e.g., PCI reset) and to close possible races between these
 	 * operations and probe/remove.
 	 */
-	device_lock_assert(devlink->dev);
+	if (devlink->dev)
+		device_lock_assert(devlink->dev);
 
 	memcpy(remote_reload_stats, devlink->stats.remote_reload_stats,
 	       sizeof(remote_reload_stats));
@@ -892,9 +893,11 @@ devlink_nl_info_fill(struct sk_buff *msg, struct devlink *devlink,
 			goto err_cancel_msg;
 	}
 
-	err = devlink_nl_driver_info_get(dev->driver, &req);
-	if (err)
-		goto err_cancel_msg;
+	if (dev) {
+		err = devlink_nl_driver_info_get(dev->driver, &req);
+		if (err)
+			goto err_cancel_msg;
+	}
 
 	genlmsg_end(msg, hdr);
 	return 0;
diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
index 67425c5d8cfc..89d08fd511cb 100644
--- a/net/devlink/devl_internal.h
+++ b/net/devlink/devl_internal.h
@@ -107,7 +107,7 @@ static inline bool devl_is_registered(struct devlink *devlink)
 
 static inline void devl_dev_lock(struct devlink *devlink, bool dev_lock)
 {
-	if (dev_lock)
+	if (dev_lock && devlink->dev)
 		device_lock(devlink->dev);
 	devl_lock(devlink);
 }
@@ -115,7 +115,7 @@ static inline void devl_dev_lock(struct devlink *devlink, bool dev_lock)
 static inline void devl_dev_unlock(struct devlink *devlink, bool dev_lock)
 {
 	devl_unlock(devlink);
-	if (dev_lock)
+	if (dev_lock && devlink->dev)
 		device_unlock(devlink->dev);
 }
 
diff --git a/net/devlink/port.c b/net/devlink/port.c
index 1d4a79c6d4d3..f19b690ebe7e 100644
--- a/net/devlink/port.c
+++ b/net/devlink/port.c
@@ -976,7 +976,9 @@ static void devlink_port_type_warn(struct work_struct *work)
 	struct devlink_port *port = container_of(to_delayed_work(work),
 						 struct devlink_port,
 						 type_warn_dw);
-	dev_warn(port->devlink->dev, "Type was not set for devlink port.");
+	if (port->devlink->dev)
+		dev_warn(port->devlink->dev,
+			 "Type was not set for devlink port.");
 }
 
 static bool devlink_port_type_should_warn(struct devlink_port *devlink_port)
@@ -1242,9 +1244,10 @@ static void __devlink_port_type_set(struct devlink_port *devlink_port,
  */
 void devlink_port_type_eth_set(struct devlink_port *devlink_port)
 {
-	dev_warn(devlink_port->devlink->dev,
-		 "devlink port type for port %d set to Ethernet without a software interface reference, device type not supported by the kernel?\n",
-		 devlink_port->index);
+	if (devlink_port->devlink->dev)
+		dev_warn(devlink_port->devlink->dev,
+			 "devlink port type for port %d set to Ethernet without a software interface reference, device type not supported by the kernel?\n",
+			 devlink_port->index);
 	__devlink_port_type_set(devlink_port, DEVLINK_PORT_TYPE_ETH, NULL);
 }
 EXPORT_SYMBOL_GPL(devlink_port_type_eth_set);
@@ -1272,7 +1275,8 @@ EXPORT_SYMBOL_GPL(devlink_port_type_ib_set);
  */
 void devlink_port_type_clear(struct devlink_port *devlink_port)
 {
-	if (devlink_port->type == DEVLINK_PORT_TYPE_ETH)
+	if (devlink_port->type == DEVLINK_PORT_TYPE_ETH &&
+	    devlink_port->devlink->dev)
 		dev_warn(devlink_port->devlink->dev,
 			 "devlink port type for port %d cleared without a software interface reference, device type not supported by the kernel?\n",
 			 devlink_port->index);
-- 
2.51.1