devlink: Allocate devlink directly in requested net namespace

There is no need in extra call indirection and check from impossible
flow where someone tries to set namespace without prior call
to devlink_alloc().

Instead of this extra logic and additional EXPORT_SYMBOL, use specialized
devlink allocation function that receives net namespace as an argument.

Such specialized API allows clear view when devlink initialized in wrong
net namespace and/or kernel users don't try to change devlink namespace
under the hood.
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/netdevsim/dev.c

@@ -1431,10 +1431,10 @@ int nsim_dev_probe(struct nsim_bus_dev *nsim_bus_dev)
 	struct devlink *devlink;
 	int err;
 
-	devlink = devlink_alloc(&nsim_dev_devlink_ops, sizeof(*nsim_dev));
+	devlink = devlink_alloc_ns(&nsim_dev_devlink_ops, sizeof(*nsim_dev),
+				   nsim_bus_dev->initial_net);
 	if (!devlink)
 		return -ENOMEM;
-	devlink_net_set(devlink, nsim_bus_dev->initial_net);
 	nsim_dev = devlink_priv(devlink);
 	nsim_dev->nsim_bus_dev = nsim_bus_dev;
 	nsim_dev->switch_id.id_len = sizeof(nsim_dev->switch_id.id);

include/net/devlink.h

@@ -1540,8 +1540,18 @@ static inline struct devlink *netdev_to_devlink(struct net_device *dev)
 struct ib_device;
 
 struct net *devlink_net(const struct devlink *devlink);
-void devlink_net_set(struct devlink *devlink, struct net *net);
-struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size);
+/* This call is intended for software devices that can create
+ * devlink instances in other namespaces than init_net.
+ *
+ * Drivers that operate on real HW must use devlink_alloc() instead.
+ */
+struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
+				 size_t priv_size, struct net *net);
+static inline struct devlink *devlink_alloc(const struct devlink_ops *ops,
+					    size_t priv_size)
+{
+	return devlink_alloc_ns(ops, priv_size, &init_net);
+}
 int devlink_register(struct devlink *devlink, struct device *dev);
 void devlink_unregister(struct devlink *devlink);
 void devlink_reload_enable(struct devlink *devlink);

net/core/devlink.c

@@ -108,19 +108,6 @@ struct net *devlink_net(const struct devlink *devlink)
 }
 EXPORT_SYMBOL_GPL(devlink_net);
 
-static void __devlink_net_set(struct devlink *devlink, struct net *net)
-{
-	write_pnet(&devlink->_net, net);
-}
-
-void devlink_net_set(struct devlink *devlink, struct net *net)
-{
-	if (WARN_ON(devlink->dev))
-		return;
-	__devlink_net_set(devlink, net);
-}
-EXPORT_SYMBOL_GPL(devlink_net_set);
-
 static struct devlink *devlink_get_from_attrs(struct net *net,
 					      struct nlattr **attrs)
 {
@@ -3921,7 +3908,7 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
 		return err;
 
 	if (dest_net && !net_eq(dest_net, curr_net))
-		__devlink_net_set(devlink, dest_net);
+		write_pnet(&devlink->_net, dest_net);
 
 	err = devlink->ops->reload_up(devlink, action, limit, actions_performed, extack);
 	devlink_reload_failed_set(devlink, !!err);
@@ -8776,15 +8763,18 @@ static bool devlink_reload_actions_valid(const struct devlink_ops *ops)
 }
 
 /**
- *	devlink_alloc - Allocate new devlink instance resources
+ *	devlink_alloc_ns - Allocate new devlink instance resources
+ *	in specific namespace
  *
  *	@ops: ops
  *	@priv_size: size of user private data
+ *	@net: net namespace
  *
  *	Allocate new devlink instance resources, including devlink index
  *	and name.
  */
-struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size)
+struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
+				 size_t priv_size, struct net *net)
 {
 	struct devlink *devlink;
 
@@ -8799,7 +8789,7 @@ struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size)
 		return NULL;
 	devlink->ops = ops;
 	xa_init_flags(&devlink->snapshot_ids, XA_FLAGS_ALLOC);
-	__devlink_net_set(devlink, &init_net);
+	write_pnet(&devlink->_net, net);
 	INIT_LIST_HEAD(&devlink->port_list);
 	INIT_LIST_HEAD(&devlink->rate_list);
 	INIT_LIST_HEAD(&devlink->sb_list);
@@ -8815,7 +8805,7 @@ struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size)
 	mutex_init(&devlink->reporters_lock);
 	return devlink;
 }
-EXPORT_SYMBOL_GPL(devlink_alloc);
+EXPORT_SYMBOL_GPL(devlink_alloc_ns);
 
 /**
  *	devlink_register - Register devlink instance