linux-kernel - Re: [PATCH v2 1/6] software node: Free resources explicitly when swnode

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Date:   Mon, 29 Mar 2021 23:45:47 +0100
From:   Daniel Scally <djrscally@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-acpi@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Yong Zhi <yong.zhi@...el.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Tianshu Qiu <tian.shu.qiu@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v2 1/6] software node: Free resources explicitly when
 swnode_register() fails

Hi Andy

On 29/03/2021 16:12, Andy Shevchenko wrote:
> Currently we have a slightly twisted logic in swnode_register().
> It frees resources that it doesn't allocate on error path and
> in once case it relies on the ->release() implementation.
>
> Untwist the logic by freeing resources explicitly when swnode_register()
> fails. Currently it happens only in fwnode_create_software_node().
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>


Reviewed-by: Daniel Scally <djrscally@...il.com>

and

Tested-by: Daniel Scally <djrscally@...il.com>

> ---
> v2: no changes
>  drivers/base/swnode.c | 29 +++++++++++++++++------------
>  1 file changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> index fa3719ef80e4..456f5fe58b58 100644
> --- a/drivers/base/swnode.c
> +++ b/drivers/base/swnode.c
> @@ -767,22 +767,19 @@ swnode_register(const struct software_node *node, struct swnode *parent,
>  	int ret;
>  
>  	swnode = kzalloc(sizeof(*swnode), GFP_KERNEL);
> -	if (!swnode) {
> -		ret = -ENOMEM;
> -		goto out_err;
> -	}
> +	if (!swnode)
> +		return ERR_PTR(-ENOMEM);
>  
>  	ret = ida_simple_get(parent ? &parent->child_ids : &swnode_root_ids,
>  			     0, 0, GFP_KERNEL);
>  	if (ret < 0) {
>  		kfree(swnode);
> -		goto out_err;
> +		return ERR_PTR(ret);
>  	}
>  
>  	swnode->id = ret;
>  	swnode->node = node;
>  	swnode->parent = parent;
> -	swnode->allocated = allocated;
>  	swnode->kobj.kset = swnode_kset;
>  	fwnode_init(&swnode->fwnode, &software_node_ops);
>  
> @@ -803,16 +800,17 @@ swnode_register(const struct software_node *node, struct swnode *parent,
>  		return ERR_PTR(ret);
>  	}
>  
> +	/*
> +	 * Assign the flag only in the successful case, so
> +	 * the above kobject_put() won't mess up with properties.
> +	 */
> +	swnode->allocated = allocated;
> +
>  	if (parent)
>  		list_add_tail(&swnode->entry, &parent->children);
>  
>  	kobject_uevent(&swnode->kobj, KOBJ_ADD);
>  	return &swnode->fwnode;
> -
> -out_err:
> -	if (allocated)
> -		property_entries_free(node->properties);
> -	return ERR_PTR(ret);
>  }
>  
>  /**
> @@ -963,6 +961,7 @@ struct fwnode_handle *
>  fwnode_create_software_node(const struct property_entry *properties,
>  			    const struct fwnode_handle *parent)
>  {
> +	struct fwnode_handle *fwnode;
>  	struct software_node *node;
>  	struct swnode *p = NULL;
>  	int ret;
> @@ -987,7 +986,13 @@ fwnode_create_software_node(const struct property_entry *properties,
>  
>  	node->parent = p ? p->node : NULL;
>  
> -	return swnode_register(node, p, 1);
> +	fwnode = swnode_register(node, p, 1);
> +	if (IS_ERR(fwnode)) {
> +		property_entries_free(node->properties);
> +		kfree(node);
> +	}
> +
> +	return fwnode;
>  }
>  EXPORT_SYMBOL_GPL(fwnode_create_software_node);
>