Re: [PATCH v2 1/3] sysfs: Support is_visible() on binary attributes

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On 09/14/2015 05:34 AM, 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.

Signed-off-by: Emilio López <emilio.lopez@xxxxxxxxxxxxxxx>

Nitpick below, but otherwise looks ok to me.

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Guenter

---

Changes from v1:
  - Don't overload is_visible, introduce is_bin_visible instead as
    discussed on the list.

  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;

Strictly speaking, the mode validation for binary attributes is new and logically
separate. Should it be mentioned in the commit log, or even be a separate patch ?

  			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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