netdev - [PATCH net-next v1 2/2] devlink: Allocate devlink directly in requested net namespace

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Message-Id: <11b72ed725699c8e477cda1c04f72c7dc090fffd.1627564383.git.leonro@nvidia.com>
Date:   Thu, 29 Jul 2021 16:17:50 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Jiri Pirko <jiri@...dia.com>
Cc:     Leon Romanovsky <leonro@...dia.com>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Parav Pandit <parav@...dia.com>
Subject: [PATCH net-next v1 2/2] devlink: Allocate devlink directly in requested net namespace

From: Leon Romanovsky <leonro@...dia.com>

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@...dia.com>
Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
 drivers/net/netdevsim/dev.c |  4 ++--
 include/net/devlink.h       | 14 ++++++++++++--
 net/core/devlink.c          | 26 ++++++++------------------
 3 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 6348307bfa84..d538a39d4225 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/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);
diff --git a/include/net/devlink.h b/include/net/devlink.h
index e48a62320407..08f4c6191e72 100644
--- a/include/net/devlink.h
+++ b/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);
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 4385930b896f..6fe453cec6e2 100644
--- a/net/core/devlink.c
+++ b/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)
 {
@@ -3920,7 +3907,7 @@ 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
-- 
2.31.1