[PATCH] node: fix device cleanups in error handling code

[PATCH] node: fix device cleanups in error handling code

[Dan Carpenter]

We can't use kfree() to free device managed resources so the kfree(dev)
is against the rules.

It's easier to write this code if we open code the device_register() as
a device_initialize() and device_add().  That way if dev_set_name() set
name fails we can call put_device() and it will clean up correctly.

Fixes: acc02a109b04 ("node: Add memory-side caching attributes")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/base/node.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index f449dbb2c746..2c36f61d30bc 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -268,21 +268,20 @@ static void node_init_cache_dev(struct node *node)
 	if (!dev)
 		return;
 
+	device_initialize(dev);
 	dev->parent = &node->dev;
 	dev->release = node_cache_release;
 	if (dev_set_name(dev, "memory_side_cache"))
-		goto free_dev;
+		goto put_device;
 
-	if (device_register(dev))
-		goto free_name;
+	if (device_add(dev))
+		goto put_device;
 
 	pm_runtime_no_callbacks(dev);
 	node->cache_dev = dev;
 	return;
-free_name:
-	kfree_const(dev->kobj.name);
-free_dev:
-	kfree(dev);
+put_device:
+	put_device(dev);
 }
 
 /**
@@ -319,25 +318,24 @@ void node_add_cache(unsigned int nid, struct node_cache_attrs *cache_attrs)
 		return;
 
 	dev = &info->dev;
+	device_initialize(dev);
 	dev->parent = node->cache_dev;
 	dev->release = node_cacheinfo_release;
 	dev->groups = cache_groups;
 	if (dev_set_name(dev, "index%d", cache_attrs->level))
-		goto free_cache;
+		goto put_device;
 
 	info->cache_attrs = *cache_attrs;
-	if (device_register(dev)) {
+	if (device_add(dev)) {
 		dev_warn(&node->dev, "failed to add cache level:%d\n",
 			 cache_attrs->level);
-		goto free_name;
+		goto put_device;
 	}
 	pm_runtime_no_callbacks(dev);
 	list_add_tail(&info->node, &node->cache_attrs);
 	return;
-free_name:
-	kfree_const(dev->kobj.name);
-free_cache:
-	kfree(info);
+put_device:
+	put_device(dev);
 }
 
 static void node_remove_caches(struct node *node)
-- 
2.30.2

Re: [PATCH] node: fix device cleanups in error handling code

[Jason Gunthorpe]

On Fri, Apr 09, 2021 at 02:01:57PM +0300, Dan Carpenter wrote:
> We can't use kfree() to free device managed resources so the kfree(dev)
> is against the rules.
> 
> It's easier to write this code if we open code the device_register() as
> a device_initialize() and device_add().  That way if dev_set_name() set
> name fails we can call put_device() and it will clean up correctly.
> 
> Fixes: acc02a109b04 ("node: Add memory-side caching attributes")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  drivers/base/node.c | 26 ++++++++++++--------------
>  1 file changed, 12 insertions(+), 14 deletions(-)

Wow, yikes, that "kfree_const(dev->kobj.name);" is really creative

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Though I dislike ignoring the error code from dev_set_name(), I think
Greg would prefer this:

diff --git a/drivers/base/node.c b/drivers/base/node.c
index f449dbb2c74666..80079e440add12 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -140,20 +140,16 @@ static struct node_access_nodes *node_init_node_access(struct node *node,
 	dev->parent = &node->dev;
 	dev->release = node_access_release;
 	dev->groups = node_access_node_groups;
-	if (dev_set_name(dev, "access%u", access))
-		goto free;
 
-	if (device_register(dev))
-		goto free_name;
+	dev_set_name(dev, "access%u", access);
+	if (device_register(dev)) {
+		put_device(dev);
+		return NULL;
+	}
 
 	pm_runtime_no_callbacks(dev);
 	list_add_tail(&access_node->list_node, &node->access_list);
 	return access_node;
-free_name:
-	kfree_const(dev->kobj.name);
-free:
-	kfree(access_node);
-	return NULL;
 }
 

(arguably a device_register_name() would be even better, if you are
handy with coccinelle there could quickly be alot of users)

Jason