[PATCH net v2] net: bareudp: add missing error handling for bareudp_link_config()

.dellink does not get called after .newlink fails,
bareudp_newlink() must undo what bareudp_configure()
has done if bareudp_link_config() fails.

v2: call bareudp_dellink(), like bareudp_dev_create() does

Fixes: 571912c69f0e ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/bareudp.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index 708171c0d628..85de5f96c02b 100644
--- a/drivers/net/bareudp.c
+++ b/drivers/net/bareudp.c

@@ -645,11 +645,20 @@ static int bareudp_link_config(struct net_device *dev,
 	return 0;
 }
 
+static void bareudp_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct bareudp_dev *bareudp = netdev_priv(dev);
+
+	list_del(&bareudp->next);
+	unregister_netdevice_queue(dev, head);
+}
+
 static int bareudp_newlink(struct net *net, struct net_device *dev,
 			   struct nlattr *tb[], struct nlattr *data[],
 			   struct netlink_ext_ack *extack)
 {
 	struct bareudp_conf conf;
+	LIST_HEAD(list_kill);
 	int err;
 
 	err = bareudp2info(data, &conf, extack);

@@ -662,17 +671,14 @@ static int bareudp_newlink(struct net *net, struct net_device *dev,
 
 	err = bareudp_link_config(dev, tb);
 	if (err)
-		return err;
+		goto err_unconfig;
 
 	return 0;
-}
-
-static void bareudp_dellink(struct net_device *dev, struct list_head *head)
-{
-	struct bareudp_dev *bareudp = netdev_priv(dev);
 
-	list_del(&bareudp->next);
-	unregister_netdevice_queue(dev, head);
+err_unconfig:
+	bareudp_dellink(dev, &list_kill);
+	unregister_netdevice_many(&list_kill);
+	return err;
 }
 
 static size_t bareudp_get_size(const struct net_device *dev)

-- 
2.26.2

On Tue, Jan 5, 2021 at 11:07 AM Jakub Kicinski [off-list ref] wrote:

.dellink does not get called after .newlink fails,
bareudp_newlink() must undo what bareudp_configure()
has done if bareudp_link_config() fails.

v2: call bareudp_dellink(), like bareudp_dev_create() does

Thanks for the update. Just one question below.

Why do we need unregister_netdevice_many() here? I think
bareudp_dellink(dev, NULL) is sufficient as we always have
one instance to unregister?

(For the same reason, bareudp_dev_create() does not need it
either.)

Thanks.

On Tue, 5 Jan 2021 12:38:54 -0800 Cong Wang wrote:

On Tue, Jan 5, 2021 at 11:07 AM Jakub Kicinski [off-list ref] wrote:

quoted

+static void bareudp_dellink(struct net_device *dev, struct list_head *head)
+{
+       struct bareudp_dev *bareudp = netdev_priv(dev);
+
+       list_del(&bareudp->next);
+       unregister_netdevice_queue(dev, head);
+}
+
 static int bareudp_newlink(struct net *net, struct net_device *dev,
                           struct nlattr *tb[], struct nlattr *data[],
                           struct netlink_ext_ack *extack)
 {
        struct bareudp_conf conf;
+       LIST_HEAD(list_kill);
        int err;

        err = bareudp2info(data, &conf, extack);

@@ -662,17 +671,14 @@ static int bareudp_newlink(struct net *net, struct net_device *dev,

        err = bareudp_link_config(dev, tb);
        if (err)
-               return err;
+               goto err_unconfig;

        return 0;
-}
-
-static void bareudp_dellink(struct net_device *dev, struct list_head *head)
-{
-       struct bareudp_dev *bareudp = netdev_priv(dev);

-       list_del(&bareudp->next);
-       unregister_netdevice_queue(dev, head);
+err_unconfig:
+       bareudp_dellink(dev, &list_kill);
+       unregister_netdevice_many(&list_kill);  

Why do we need unregister_netdevice_many() here? I think
bareudp_dellink(dev, NULL) is sufficient as we always have
one instance to unregister?

(For the same reason, bareudp_dev_create() does not need it
either.)

Ack, I'm following how bareudp_dev_create() is written. 

I can follow up in net-next and change both, sounds good?

On Tue, Jan 5, 2021 at 2:39 PM Jakub Kicinski [off-list ref] wrote:

On Tue, 5 Jan 2021 12:38:54 -0800 Cong Wang wrote:

quoted

On Tue, Jan 5, 2021 at 11:07 AM Jakub Kicinski [off-list ref] wrote:

quoted

+static void bareudp_dellink(struct net_device *dev, struct list_head *head)
+{
+       struct bareudp_dev *bareudp = netdev_priv(dev);
+
+       list_del(&bareudp->next);
+       unregister_netdevice_queue(dev, head);
+}
+
 static int bareudp_newlink(struct net *net, struct net_device *dev,
                           struct nlattr *tb[], struct nlattr *data[],
                           struct netlink_ext_ack *extack)
 {
        struct bareudp_conf conf;
+       LIST_HEAD(list_kill);
        int err;

        err = bareudp2info(data, &conf, extack);

@@ -662,17 +671,14 @@ static int bareudp_newlink(struct net *net, struct net_device *dev,

        err = bareudp_link_config(dev, tb);
        if (err)
-               return err;
+               goto err_unconfig;

        return 0;
-}
-
-static void bareudp_dellink(struct net_device *dev, struct list_head *head)
-{
-       struct bareudp_dev *bareudp = netdev_priv(dev);

-       list_del(&bareudp->next);
-       unregister_netdevice_queue(dev, head);
+err_unconfig:
+       bareudp_dellink(dev, &list_kill);
+       unregister_netdevice_many(&list_kill);

Why do we need unregister_netdevice_many() here? I think
bareudp_dellink(dev, NULL) is sufficient as we always have
one instance to unregister?

(For the same reason, bareudp_dev_create() does not need it
either.)

Ack, I'm following how bareudp_dev_create() is written.

I can follow up in net-next and change both, sounds good?

Yes, either way is fine.

Thanks.

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Tue,  5 Jan 2021 11:07:25 -0800 you wrote:

.dellink does not get called after .newlink fails,
bareudp_newlink() must undo what bareudp_configure()
has done if bareudp_link_config() fails.

v2: call bareudp_dellink(), like bareudp_dev_create() does

Fixes: 571912c69f0e ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

[...]

Here is the summary with links:
  - [net,v2] net: bareudp: add missing error handling for bareudp_link_config()
    https://git.kernel.org/netdev/net/c/94bcfdbff0c2

You are awesome, thank you!
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