On 5/5/22 12:37, Rob Herring wrote:
> On Wed, May 04, 2022 at 05:40:31PM +0200, Clément Léger wrote:
>> Add function which allows to dynamically allocate and free properties.
>> Use this function internally for all code that used the same logic
>> (mainly __of_prop_dup()).
>>
>> Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
>> ---
>> drivers/of/dynamic.c | 101 ++++++++++++++++++++++++++++++-------------
>> include/linux/of.h | 16 +++++++
>> 2 files changed, 88 insertions(+), 29 deletions(-)
>>
>> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
>> index cd3821a6444f..e8700e509d2e 100644
>> --- a/drivers/of/dynamic.c
>> +++ b/drivers/of/dynamic.c
>> @@ -313,9 +313,7 @@ static void property_list_free(struct property *prop_list)
>>
>> for (prop = prop_list; prop != NULL; prop = next) {
>> next = prop->next;
>> - kfree(prop->name);
>> - kfree(prop->value);
>> - kfree(prop);
>> + of_property_free(prop);
>> }
>> }
>>
>> @@ -367,48 +365,95 @@ void of_node_release(struct kobject *kobj)
>> }
>>
>> /**
>> - * __of_prop_dup - Copy a property dynamically.
>> - * @prop: Property to copy
>> + * of_property_free - Free a property allocated dynamically.
>> + * @prop: Property to be freed
>> + */
>> +void of_property_free(const struct property *prop)
>> +{
>> + kfree(prop->value);
>> + kfree(prop->name);
>> + kfree(prop);
>> +}
>> +EXPORT_SYMBOL(of_property_free);
>> +
>> +/**
>> + * of_property_alloc - Allocate a property dynamically.
>> + * @name: Name of the new property
>> + * @value: Value that will be copied into the new property value
>> + * @value_len: length of @value to be copied into the new property value
>> + * @len: Length of new property value, must be greater than @value_len
>
> What's the usecase for the lengths being different? That doesn't seem
> like a common case, so perhaps handle it with a NULL value and
> non-zero length. Then the caller has to deal with populating
> prop->value.
>
>> * @allocflags: Allocation flags (typically pass GFP_KERNEL)
>> *
>> - * Copy a property by dynamically allocating the memory of both the
>> + * Create a property by dynamically allocating the memory of both the
>> * property structure and the property name & contents. The property's
>> * flags have the OF_DYNAMIC bit set so that we can differentiate between
>> * dynamically allocated properties and not.
>> *
>> * Return: The newly allocated property or NULL on out of memory error.
>> */
>> -struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
>> +struct property *of_property_alloc(const char *name, const void *value,
>> + int value_len, int len, gfp_t allocflags)
>> {
>> - struct property *new;
>> + int alloc_len = len;
>> + struct property *prop;
>> +
>> + if (len < value_len)
>> + return NULL;
>>
>> - new = kzalloc(sizeof(*new), allocflags);
>> - if (!new)
>> + prop = kzalloc(sizeof(*prop), allocflags);
>> + if (!prop)
>> return NULL;
>>
>> + prop->name = kstrdup(name, allocflags);
>> + if (!prop->name)
>> + goto out_err;
>> +
>> /*
>> - * 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.
>> + * Even if the property has no value, it must be set to a
>> + * non-null value since of_get_property() is used to check
>> + * some values that might or not have a values (ranges for
>> + * instance). Moreover, when the node is released, prop->value
>> + * is kfreed so the memory must come from kmalloc.
>
> Allowing for NULL value didn't turn out well...
>
> We know that we can do the kfree because OF_DYNAMIC is set IIRC...
>
> If we do 1 allocation for prop and value, then we can test
> for "prop->value == prop + 1" to determine if we need to free or not.
If its a single allocation do we even need a test? Doesn't kfree(prop) take care
of the property and the trailing memory allocated for the value?
-Tyrel
>
>> */
>> - new->name = kstrdup(prop->name, allocflags);
>> - new->value = kmemdup(prop->value, prop->length, allocflags);
>> - new->length = prop->length;
>> - if (!new->name || !new->value)
>> - goto err_free;
>> + if (!alloc_len)
>> + alloc_len = 1;
>>
>> - /* mark the property as dynamic */
>> - of_property_set_flag(new, OF_DYNAMIC);
>> + prop->value = kzalloc(alloc_len, allocflags);
>> + if (!prop->value)
>> + goto out_err;
>>
>> - return new;
>> + if (value)
>> + memcpy(prop->value, value, value_len);
>> +
>> + prop->length = len;
>> + of_property_set_flag(prop, OF_DYNAMIC);
>> +
>> + return prop;
>> +
>> +out_err:
>> + of_property_free(prop);
>>
>> - err_free:
>> - kfree(new->name);
>> - kfree(new->value);
>> - kfree(new);
>> return NULL;
>> }
>> +EXPORT_SYMBOL(of_property_alloc);
>> +
>> +/**
>> + * __of_prop_dup - Copy a property dynamically.
>> + * @prop: Property to copy
>> + * @allocflags: Allocation flags (typically pass GFP_KERNEL)
>> + *
>> + * Copy a property by dynamically allocating the memory of both the
>> + * property structure and the property name & contents. The property's
>> + * flags have the OF_DYNAMIC bit set so that we can differentiate between
>> + * dynamically allocated properties and not.
>> + *
>> + * Return: The newly allocated property or NULL on out of memory error.
>> + */
>> +struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
>> +{
>> + return of_property_alloc(prop->name, prop->value, prop->length,
>> + prop->length, allocflags);
>
> This can now be a static inline.
>
>> +}
>>
>> /**
>> * __of_node_dup() - Duplicate or create an empty device node dynamically.
>> @@ -447,9 +492,7 @@ struct device_node *__of_node_dup(const struct device_node *np,
>> if (!new_pp)
>> goto err_prop;
>> if (__of_add_property(node, new_pp)) {
>> - kfree(new_pp->name);
>> - kfree(new_pp->value);
>> - kfree(new_pp);
>> + of_property_free(new_pp);
>> goto err_prop;
>> }
>> }
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 04971e85fbc9..6b345eb71c19 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -1463,6 +1463,11 @@ enum of_reconfig_change {
>> };
>>
>> #ifdef CONFIG_OF_DYNAMIC
>> +extern struct property *of_property_alloc(const char *name, const void *value,
>> + int value_len, int len,
>> + gfp_t allocflags);
>> +extern void of_property_free(const struct property *prop);
>> +
>> extern int of_reconfig_notifier_register(struct notifier_block *);
>> extern int of_reconfig_notifier_unregister(struct notifier_block *);
>> extern int of_reconfig_notify(unsigned long, struct of_reconfig_data *rd);
>> @@ -1507,6 +1512,17 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
>> return of_changeset_action(ocs, OF_RECONFIG_UPDATE_PROPERTY, np, prop);
>> }
>> #else /* CONFIG_OF_DYNAMIC */
>> +
>> +static inline struct property *of_property_alloc(const char *name,
>> + const void *value,
>> + int value_len, int len,
>> + gfp_t allocflags)
>> +{
>> + return NULL;
>> +}
>> +
>> +static inline void of_property_free(const struct property *prop) {}
>> +
>> static inline int of_reconfig_notifier_register(struct notifier_block *nb)
>> {
>> return -EINVAL;
>> --
>> 2.34.1
>>
>>
