Re: [PATCH 3/4] of: changesets: Introduce changeset helper methods

[Pantelis Antoniou]

Hi Rob,

> On May 9, 2016, at 17:27 , Rob Herring <robherring2@xxxxxxxxx> wrote:
> 
> On Mon, May 9, 2016 at 8:20 AM, Pantelis Antoniou
> <pantelis.antoniou@xxxxxxxxxxxx> wrote:
>> Changesets are very powerful, but the lack of a helper API
>> makes using them cumbersome. Introduce a simple copy based
>> API that makes things considerably easier.
>> 
>> To wit, adding a property using the raw API.
>> 
>>        struct property *prop;
>>        prop = kzalloc(sizeof(*prop)), GFP_KERNEL);
>>        prop->name = kstrdup("compatible");
>>        prop->value = kstrdup("foo,bar");
>>        prop->length = strlen(prop->value) + 1;
>>        of_changeset_add_property(ocs, np, prop);
>> 
>> while using the helper API
>> 
>>        of_changeset_add_property_string(ocs, np, "compatible",
>>                        "foo,bar");
> 
> Seems useful. Do we not have any users that can be converted?
> 

There is a user for this, which will be shortly posted.


> [...]
> 
>> +static int __of_changeset_add_update_property_copy(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name, const void *value,
>> +               int length, bool update)
>> +{
>> +       struct property *prop;
>> +       char *new_name;
>> +       void *new_value;
>> +       int ret = -ENOMEM;
>> +
>> +       prop = kzalloc(sizeof(*prop), GFP_KERNEL);
>> +       if (!prop)
>> +               goto out_no_prop;
> 
> Just return here.
> 

OK

>> +
>> +       new_name = kstrdup(name, GFP_KERNEL);
>> +       if (!new_name)
>> +               goto out_no_name;
>> +
>> +       /*
>> +        * NOTE: There is no check for zero length value.
>> +        * In case of a boolean property, this will allocate a value
>> +        * of zero bytes. We do this to work around the use
>> +        * of of_get_property() calls on boolean values.
>> +        */
>> +       new_value = kmemdup(value, length, GFP_KERNEL);
>> +       if (!new_value)
>> +               goto out_no_value;
>> +
>> +       of_property_set_flag(prop, OF_DYNAMIC);
>> +
>> +       prop->name = new_name;
>> +       prop->value = new_value;
>> +       prop->length = length;
>> +
>> +       if (!update)
>> +               ret = of_changeset_add_property(ocs, np, prop);
>> +       else
>> +               ret = of_changeset_update_property(ocs, np, prop);
>> +
>> +       if (ret != 0)
> 
> if (!ret)
>  return 0;
> 
> 

>> +               goto out_no_add;
>> +
>> +       return 0;
>> +
>> +out_no_add:
> 
> ... and remove all this.
> 

Err, thereâs an exit path here from kmemdup (goto err_no_value).
Weâll be leaking memory on error.

>> +       kfree(prop->value);
>> +out_no_value:
>> +       kfree(prop->name);
>> +out_no_name:
>> +       kfree(prop);
>> +out_no_prop:
>> +       return ret;
>> +}
>> +
>> +static int __of_changeset_add_update_property_string(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name, const char *str,
>> +               bool update)
>> +{
>> +       return __of_changeset_add_update_property_copy(ocs, np, name, str,
>> +                       strlen(str) + 1, update);
>> +}
>> +
>> +static int __of_changeset_add_update_property_stringv(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name,
>> +               const char *fmt, va_list vargs, bool update)
>> +{
>> +       char *str;
>> +       int ret;
>> +
>> +       str = kvasprintf(GFP_KERNEL, fmt, vargs);
>> +       if (!str)
>> +               return -ENOMEM;
>> +
>> +       ret = __of_changeset_add_update_property_string(ocs, np, name, str, update);
>> +
>> +       kfree(str);
>> +
>> +       return ret;
>> +}
>> +
>> +static int __of_changeset_add_update_property_string_list(
>> +               struct of_changeset *ocs, struct device_node *np, const char *name,
>> +               const char **strs, int count, bool update)
>> +{
>> +       int total = 0, i, ret;
>> +       char *value, *s;
>> +
>> +       for (i = 0; i < count; i++) {
>> +               /* check if  it's NULL */
>> +               if (!strs[i])
>> +                       return -EINVAL;
>> +               total += strlen(strs[i]) + 1;
>> +       }
>> +
>> +       value = kmalloc(total, GFP_KERNEL);
>> +       if (!value)
>> +               return -ENOMEM;
>> +
>> +       for (i = 0, s = value; i < count; i++) {
>> +               /* no need to check for NULL, check above */
>> +               strcpy(s, strs[i]);
>> +               s += strlen(strs[i]) + 1;
>> +       }
>> +
>> +       ret = __of_changeset_add_update_property_copy(ocs, np, name, value,
>> +                       total, update);
>> +
>> +       kfree(value);
>> +
>> +       return ret;
>> +}
>> +
>> +static int __of_changeset_add_update_property_u32(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name, u32 val, bool update)
>> +{
>> +       /* in place */
>> +       val = cpu_to_be32(val);
> 
> Kill this function and move this to the 2 callers.
> 
>> +       return __of_changeset_add_update_property_copy(ocs, np, name, &val,
>> +                       sizeof(val), update);
>> +}
>> +
>> +static int __of_changeset_add_update_property_bool(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name, bool update)
>> +{
> 
> I think this intermediate function could be killed off too.
> 
>> +       return __of_changeset_add_update_property_copy(ocs, np, name, "", 0,
>> +                       update);
>> +}
> 
> [...]
> 
>> +static struct device_node *
>> +__of_changeset_node_move_one(struct of_changeset *ocs,
>> +               struct device_node *np, struct device_node *new_parent)
>> +{
>> +       struct device_node *np2;
>> +       const char *unitname;
>> +       int err;
>> +
>> +       err = of_changeset_detach_node(ocs, np);
>> +       if (err)
>> +               return ERR_PTR(err);
>> +
>> +       unitname = strrchr(np->full_name, '/');
>> +       if (!unitname)
>> +               unitname = np->full_name;
>> +
>> +       np2 = __of_node_dup(np, "%s/%s",
>> +                       new_parent->full_name, unitname);
>> +       if (!np2)
>> +               return ERR_PTR(-ENOMEM);
>> +       np2->parent = new_parent;
>> +
>> +       err = of_changeset_attach_node(ocs, np2);
>> +       if (err)
>> +               return ERR_PTR(err);
>> +
>> +       return np2;
>> +}
>> +
>> +/**
>> + * of_changeset_node_move_to - Moves a subtree to a new place in
>> + *                             the tree
>> + *
>> + * @ocs:       changeset pointer
>> + * @np:                device node pointer to be moved
>> + * @to:                device node of the new parent
>> + *
>> + * Moves a subtree to a new place in the tree.
>> + * Note that a move is a safe operation because the phandles
>> + * remain valid.
> 
> I'm having a hard time imagining a usecase for this one. I would drop
> until we have a user in tree.
> 

Thereâs a use case - it will be apparent with the next patches.
 
>> + *
>> + * Returns zero on success, a negative error value otherwise.
>> + */
>> +int of_changeset_node_move(struct of_changeset *ocs,
>> +               struct device_node *np, struct device_node *new_parent)
>> +{
>> +       struct device_node *npc, *nppc;
>> +
>> +       /* move the root first */
>> +       nppc = __of_changeset_node_move_one(ocs, np, new_parent);
>> +       if (IS_ERR(nppc))
>> +               return PTR_ERR(nppc);
>> +
>> +       /* move the subtrees next */
>> +       for_each_child_of_node(np, npc) {
>> +               nppc = __of_changeset_node_move_one(ocs, npc, nppc);
>> +               if (IS_ERR(nppc)) {
>> +                       of_node_put(npc);
>> +                       return PTR_ERR(nppc);
>> +               }
>> +       }
>> +
>> +       return 0;
>> +}
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 3175803..f015911 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -1037,6 +1037,42 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
>> {
>>        return of_changeset_action(ocs, OF_RECONFIG_UPDATE_PROPERTY, np, prop);
>> }
>> +
>> +struct device_node *of_changeset_create_device_nodev(
>> +       struct of_changeset *ocs, struct device_node *parent,
>> +       const char *fmt, va_list vargs);
>> +__printf(3, 4) struct device_node *of_changeset_create_device_node(
>> +       struct of_changeset *ocs, struct device_node *parent,
>> +       const char *fmt, ...);
>> +int of_changeset_add_property_copy(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name,
>> +       const void *value, int length);
>> +int of_changeset_add_property_string(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name, const char *str);
>> +__printf(4, 5) int of_changeset_add_property_stringf(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name, const char *fmt, ...);
>> +int of_changeset_add_property_string_list(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name, const char **strs, int count);
>> +int of_changeset_add_property_u32(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name, u32 val);
>> +int of_changeset_add_property_bool(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name);
>> +int of_changeset_update_property_copy(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name,
>> +       const void *value, int length);
>> +int of_changeset_update_property_string(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name, const char *str);
>> +__printf(4, 5) int of_changeset_update_property_stringf(struct of_changeset *ocs,
>> +               struct device_node *np, const char *name, const char *fmt, ...);
>> +int of_changeset_update_property_string_list(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name, const char **strs, int count);
>> +int of_changeset_update_property_u32(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name, u32 val);
>> +int of_changeset_update_property_bool(struct of_changeset *ocs,
>> +       struct device_node *np, const char *name);
>> +int of_changeset_node_move(struct of_changeset *ocs,
>> +       struct device_node *np, struct device_node *new_parent);
> 
> A bunch of these can be static inline wrappers.
> 
> You need EXPORT_SYMBOL_GPL on these as well.
> 

I will add the exports.

> Rob

Regards

â Pantelis