linux-kernel - Re: [PATCH 1/4] sysfs: Support is

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Message-ID: <56000920.4010105@collabora.co.uk>
Date:	Mon, 21 Sep 2015 10:41:52 -0300
From:	Emilio López <emilio.lopez@...labora.co.uk>
To:	gregkh@...uxfoundation.org, olof@...om.net, kgene@...nel.org,
	k.kozlowski@...sung.com, linux@...ck-us.net
Cc:	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH 1/4] sysfs: Support is_visible() on binary attributes

This is v3, even if the subject doesn't say so. This is what happens 
when you forget to use --reroll-count and try to fix it manually :)

Emilio

On 21/09/15 10:38, Emilio López wrote:
> According to the sysfs header file:
>
>      "The returned value will replace static permissions defined in
>       struct attribute or struct bin_attribute."
>
> but this isn't the case, as is_visible is only called on struct attribute
> only. This patch introduces a new is_bin_visible() function to implement
> the same functionality for binary attributes, and updates documentation
> accordingly.
>
> Note that to keep functionality and code similar to that of normal
> attributes, the mode is now checked as well to ensure it contains only
> read/write permissions or SYSFS_PREALLOC.
>
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> Signed-off-by: Emilio López <emilio.lopez@...labora.co.uk>
> ---
>
> Changes from v1:
>   - Don't overload is_visible, introduce is_bin_visible instead as
>     discussed on the list.
>
> Changes from v2:
>   - Note change in mode checking on the commit log
>   - Add Guenter's reviewed-by
>
>   fs/sysfs/group.c      | 17 +++++++++++++++--
>   include/linux/sysfs.h | 18 ++++++++++++++----
>   2 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index 39a0199..51b56e6 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -73,13 +73,26 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
>   	}
>
>   	if (grp->bin_attrs) {
> -		for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++) {
> +		for (i = 0, bin_attr = grp->bin_attrs; *bin_attr; i++, bin_attr++) {
> +			umode_t mode = (*bin_attr)->attr.mode;
> +
>   			if (update)
>   				kernfs_remove_by_name(parent,
>   						(*bin_attr)->attr.name);
> +			if (grp->is_bin_visible) {
> +				mode = grp->is_bin_visible(kobj, *bin_attr, i);
> +				if (!mode)
> +					continue;
> +			}
> +
> +			WARN(mode & ~(SYSFS_PREALLOC | 0664),
> +			     "Attribute %s: Invalid permissions 0%o\n",
> +			     (*bin_attr)->attr.name, mode);
> +
> +			mode &= SYSFS_PREALLOC | 0664;
>   			error = sysfs_add_file_mode_ns(parent,
>   					&(*bin_attr)->attr, true,
> -					(*bin_attr)->attr.mode, NULL);
> +					mode, NULL);
>   			if (error)
>   				break;
>   		}
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index 9f65758..2f66050 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -64,10 +64,18 @@ do {							\
>    *		a new subdirectory with this name.
>    * @is_visible:	Optional: Function to return permissions associated with an
>    *		attribute of the group. Will be called repeatedly for each
> - *		attribute in the group. Only read/write permissions as well as
> - *		SYSFS_PREALLOC are accepted. Must return 0 if an attribute is
> - *		not visible. The returned value will replace static permissions
> - *		defined in struct attribute or struct bin_attribute.
> + *		non-binary attribute in the group. Only read/write
> + *		permissions as well as SYSFS_PREALLOC are accepted. Must
> + *		return 0 if an attribute is not visible. The returned value
> + *		will replace static permissions defined in struct attribute.
> + * @is_bin_visible:
> + *		Optional: Function to return permissions associated with a
> + *		binary attribute of the group. Will be called repeatedly
> + *		for each binary attribute in the group. Only read/write
> + *		permissions as well as SYSFS_PREALLOC are accepted. Must
> + *		return 0 if a binary attribute is not visible. The returned
> + *		value will replace static permissions defined in
> + *		struct bin_attribute.
>    * @attrs:	Pointer to NULL terminated list of attributes.
>    * @bin_attrs:	Pointer to NULL terminated list of binary attributes.
>    *		Either attrs or bin_attrs or both must be provided.
> @@ -76,6 +84,8 @@ struct attribute_group {
>   	const char		*name;
>   	umode_t			(*is_visible)(struct kobject *,
>   					      struct attribute *, int);
> +	umode_t			(*is_bin_visible)(struct kobject *,
> +						  struct bin_attribute *, int);
>   	struct attribute	**attrs;
>   	struct bin_attribute	**bin_attrs;
>   };
>
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