linux-kernel - Re: [PATCH RFC V2 1/3] of: dynamic: Add of_create_node() and of_destroy

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Date:   Tue, 1 Nov 2022 11:16:35 -0700
From:   Lizhi Hou <lizhi.hou@....com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <robh@...nel.org>,
        <frowand.list@...il.com>, <helgaas@...nel.org>
CC:     <clement.leger@...tlin.com>, <max.zhen@....com>,
        <sonal.santan@....com>, <larry.liu@....com>, <brian.xu@....com>,
        <stefano.stabellini@...inx.com>, <trix@...hat.com>
Subject: Re: [PATCH RFC V2 1/3] of: dynamic: Add of_create_node() and
 of_destroy_node()


On 11/1/22 00:47, Christophe JAILLET wrote:
> Le 12/10/2022 à 20:13, Lizhi Hou a écrit :
>> of_create_node() creates device node and apply to base tree dynamically.
>> The parent device node and full name are required for creating the node.
>> And the caller can also provide a property array for the node.
>>
>> Inside this function, it creates a changeset. Then the new device node
>> and properties are added to the changeset and applied to base tree. The
>> pointer of this changeset is saved in device node private data.
>>
>> of_destroy_node() removes the node created by of_create_node() from the
>> base tree and free it. It gets the changeset pointer from device node
>> private data and call of_changeset_destroy() to free everything.
>>
>> Signed-off-by: Lizhi Hou <lizhi.hou@....com>
>> Signed-off-by: Sonal Santan <sonal.santan@....com>
>> Signed-off-by: Max Zhen <max.zhen@....com>
>> Signed-off-by: Brian Xu <brian.xu@....com>
>> ---
>>   drivers/of/dynamic.c | 80 ++++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/of.h   |  4 +++
>>   2 files changed, 84 insertions(+)
>>
>> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
>> index cd3821a6444f..eca28b723706 100644
>> --- a/drivers/of/dynamic.c
>> +++ b/drivers/of/dynamic.c
>> @@ -934,3 +934,83 @@ int of_changeset_action(struct of_changeset 
>> *ocs, unsigned long action,
>>       return 0;
>>   }
>>   EXPORT_SYMBOL_GPL(of_changeset_action);
>> +
>> +/**
>> + * of_create_node - Dynamically create a device node and apply it to 
>> base tree
>> + *
>> + * @parent: Pointer to parent device node
>> + * @full_name: Full name of device node
>> + * @props: Pointer to property array
>> + *
>> + * Return: Pointer to the created device node or NULL in case of an 
>> error.
>> + */
>> +struct device_node *of_create_node(struct device_node *parent,
>> +                   const char *full_name,
>> +                   struct property *props)
>> +{
>> +    struct of_changeset *cset;
>> +    struct property *new_pp;
>> +    struct device_node *np;
>> +    int ret, i;
>> +
>> +    cset = kzalloc(sizeof(*cset), GFP_KERNEL);
>
> Hi,
>
> kmalloc() would be enough. of_changeset_init() below already calls 
> memset().
Ok.
>
>> +    if (!cset)
>> +        return NULL;
>> +
>> +    of_changeset_init(cset);
>> +
>> +    np = __of_node_dup(NULL, full_name);
>> +    if (!np)
>> +        goto failed;
>
> 'cset' seems to be leaking if __of_node_dup() fails.

Will fix this. Thanks.


Lizhi

>
>> +    np->parent = parent;
>> +
>> +    ret = of_changeset_attach_node(cset, np);
>> +    if (ret)
>> +        goto failed;
>> +
>> +    if (props) {
>> +        for (i = 0; props[i].name; i++) {
>> +            new_pp = __of_prop_dup(&props[i], GFP_KERNEL);
>> +            if (!new_pp)
>> +                goto failed;
>> +            ret = of_changeset_add_property(cset, np, new_pp);
>> +            if (ret) {
>> +                kfree(new_pp->name);
>> +                kfree(new_pp->value);
>> +                kfree(new_pp);
>> +                goto failed;
>> +            }
>> +        }
>> +    }
>> +
>> +    ret = of_changeset_apply(cset);
>> +    if (ret)
>> +        goto failed;
>> +
>> +    np->data = cset;
>> +
>> +    return np;
>> +
>> +failed:
>> +    of_changeset_destroy(cset);
>> +    if (np)
>> +        of_node_put(np);
>> +
>> +    return NULL;
>> +}
>> +
>> +/**
>> + * of_destroy_node - Destroy a dynamically created device node
>> + *
>> + * @np: Pointer to dynamically created device node
>> + *
>> + */
>> +void of_destroy_node(struct device_node *np)
>> +{
>> +    struct of_changeset *cset;
>> +
>> +    cset = (struct of_changeset *)np->data;
>> +    of_changeset_destroy(cset);
>> +    of_node_put(np);
>> +    kfree(cset);
>> +}
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 766d002bddb9..493ef957c1a8 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -1475,6 +1475,10 @@ extern int of_changeset_revert(struct 
>> of_changeset *ocs);
>>   extern int of_changeset_action(struct of_changeset *ocs,
>>           unsigned long action, struct device_node *np,
>>           struct property *prop);
>> +struct device_node *of_create_node(struct device_node *parent,
>> +                   const char *full_name,
>> +                   struct property *props);
>> +void of_destroy_node(struct device_node *np);
>>     static inline int of_changeset_attach_node(struct of_changeset *ocs,
>>           struct device_node *np)
>