On Fri, Jan 16, 2015 at 04:29:10PM -0500, Vivien Didelot wrote:
> Using the optional is_visible function, it is actually possible to
> either hide an attribute, or add a new permission, but not remove one.
What code wants to remove attributes?
> This commit uses all the UGO bits returned by is_visible instead of
> OR'ing them with the default attribute mode.
>
> Concretely, this allows a driver to use macros like DEVICE_ATTR_RW to
> set the attribute show and store functions and remove the S_IWUSR
> permission in is_visible if the implementation doesn't provide a setter.
What bus wants to do this?
> Signed-off-by: Vivien Didelot <vivien.dide...@savoirfairelinux.com>
> ---
> fs/sysfs/group.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index 7d2a860..a8cfe03 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -41,7 +41,7 @@ static int create_files(struct kernfs_node *parent, struct
> kobject *kobj,
>
> if (grp->attrs) {
> for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
> - umode_t mode = 0;
> + umode_t mode = (*attr)->mode;
>
> /*
> * In update mode, we're changing the permissions or
> @@ -51,13 +51,15 @@ static int create_files(struct kernfs_node *parent,
> struct kobject *kobj,
> if (update)
> kernfs_remove_by_name(parent, (*attr)->name);
> if (grp->is_visible) {
> - mode = grp->is_visible(kobj, *attr, i);
> - if (!mode)
> + umode_t ugo = grp->is_visible(kobj, *attr, i);
> +
> + if (!(ugo & S_IRWXUGO))
> continue;
> +
> + mode = (mode & ~S_IRWXUGO) | (ugo & S_IRWXUGO);
Please document what you are doing here in the code, it's not obvious at
first glance.
> }
> error = sysfs_add_file_mode_ns(parent, *attr, false,
> - (*attr)->mode | mode,
> - NULL);
> + mode, NULL);
Any chance this is going to break existing code that isn't expecting
this type of change in functionality?
thanks,
greg k-h
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