Re: [PATCH v2 2/2] nvmem: core: use is_bin_visible for permissions

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Mar 25, 2020 at 10:01:38AM +0000, Srinivas Kandagatla wrote:
> By using is_bin_visible callback to set permissions will remove a
> large list of attribute groups. These group permissions can be
> dynamically derived in the callback.
> 
> Also add checks for read/write callbacks and set permissions accordingly.
> 
> Suggested-by: Greg KH <gregkh@linuxfoundation.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
> Changes since v1:
> 	- Updated permissions setup logic as suggested by Greg
> 	- Added checks for callbacks.
> 
>  drivers/nvmem/nvmem-sysfs.c | 85 +++++++++++++------------------------
>  1 file changed, 29 insertions(+), 56 deletions(-)
> 
> diff --git a/drivers/nvmem/nvmem-sysfs.c b/drivers/nvmem/nvmem-sysfs.c
> index 8759c4470012..68ad8aef79d4 100644
> --- a/drivers/nvmem/nvmem-sysfs.c
> +++ b/drivers/nvmem/nvmem-sysfs.c
> @@ -104,6 +104,28 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
>  	return count;
>  }
>  
> +static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
> +					 struct bin_attribute *attr, int i)
> +{
> +	struct device *dev = container_of(kobj, struct device, kobj);
> +	struct nvmem_device *nvmem = to_nvmem_device(dev);
> +	umode_t mode = 0400;
> +
> +	if (!nvmem->root_only)
> +		mode |= 0044;
> +
> +	if (!nvmem->read_only)
> +		mode |= 0200;
> +
> +	if (!nvmem->reg_write)
> +		mode &= ~0200;
> +
> +	if (!nvmem->reg_read)
> +		mode &= ~0444;
> +
> +	return mode;
> +}
> +
>  /* default read/write permissions */
>  static struct bin_attribute bin_attr_rw_nvmem = {
>  	.attr	= {
> @@ -114,18 +136,19 @@ static struct bin_attribute bin_attr_rw_nvmem = {
>  	.write	= bin_attr_nvmem_write,
>  };
>  
> -static struct bin_attribute *nvmem_bin_rw_attributes[] = {
> +static struct bin_attribute *nvmem_bin_attributes[] = {
>  	&bin_attr_rw_nvmem,
>  	NULL,
>  };
>  
> -static const struct attribute_group nvmem_bin_rw_group = {
> -	.bin_attrs	= nvmem_bin_rw_attributes,
> +static const struct attribute_group nvmem_bin_group = {
> +	.bin_attrs	= nvmem_bin_attributes,
>  	.attrs		= nvmem_attrs,
> +	.is_bin_visible = nvmem_bin_attr_is_visible,
>  };
>  
> -static const struct attribute_group *nvmem_rw_dev_groups[] = {
> -	&nvmem_bin_rw_group,
> +static const struct attribute_group *nvmem_dev_groups[] = {
> +	&nvmem_bin_group,
>  	NULL,
>  };
>  
> @@ -138,21 +161,6 @@ static struct bin_attribute bin_attr_ro_nvmem = {
>  	.read	= bin_attr_nvmem_read,
>  };
>  
> -static struct bin_attribute *nvmem_bin_ro_attributes[] = {
> -	&bin_attr_ro_nvmem,
> -	NULL,
> -};
> -
> -static const struct attribute_group nvmem_bin_ro_group = {
> -	.bin_attrs	= nvmem_bin_ro_attributes,
> -	.attrs		= nvmem_attrs,
> -};
> -
> -static const struct attribute_group *nvmem_ro_dev_groups[] = {
> -	&nvmem_bin_ro_group,
> -	NULL,
> -};
> -
>  /* default read/write permissions, root only */
>  static struct bin_attribute bin_attr_rw_root_nvmem = {
>  	.attr	= {
> @@ -163,21 +171,6 @@ static struct bin_attribute bin_attr_rw_root_nvmem = {
>  	.write	= bin_attr_nvmem_write,
>  };
>  
> -static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
> -	&bin_attr_rw_root_nvmem,
> -	NULL,
> -};
> -
> -static const struct attribute_group nvmem_bin_rw_root_group = {
> -	.bin_attrs	= nvmem_bin_rw_root_attributes,
> -	.attrs		= nvmem_attrs,
> -};
> -
> -static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
> -	&nvmem_bin_rw_root_group,
> -	NULL,
> -};
> -
>  /* read only permission, root only */
>  static struct bin_attribute bin_attr_ro_root_nvmem = {
>  	.attr	= {
> @@ -187,31 +180,11 @@ static struct bin_attribute bin_attr_ro_root_nvmem = {
>  	.read	= bin_attr_nvmem_read,
>  };
>  
> -static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
> -	&bin_attr_ro_root_nvmem,
> -	NULL,
> -};
> -
> -static const struct attribute_group nvmem_bin_ro_root_group = {
> -	.bin_attrs	= nvmem_bin_ro_root_attributes,
> -	.attrs		= nvmem_attrs,
> -};
> -
> -static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
> -	&nvmem_bin_ro_root_group,
> -	NULL,
> -};
> -
>  const struct attribute_group **nvmem_sysfs_get_groups(
>  					struct nvmem_device *nvmem,
>  					const struct nvmem_config *config)

You no longer need any parameters for this function, right?

Also, you really don't even need the function, just point to the
variable instead.

thanks,

greg k-h