From d4acd722b7bb5f48b9fc3848e8c2a845b100d84f Mon Sep 17 00:00:00 2001
From: James Bottomley <James.Bottomley@HansenPartnership.com>
Date: Wed, 31 Oct 2007 09:38:04 -0500
Subject: [PATCH] [SCSI] sysfs: add filter function to groups

This patch allows the various users of attribute_groups to selectively
allow the appearance of group attributes.  The primary consumer of
this will be the transport classes in which we currently have
elaborate attribute selection algorithms to do this same thing.

Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 fs/sysfs/group.c      | 26 ++++++++++++++++----------
 include/linux/sysfs.h |  2 ++
 kernel/params.c       |  2 +-
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index d1972374655a..0871c3dadce1 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -16,25 +16,31 @@
 #include "sysfs.h"
 
 
-static void remove_files(struct sysfs_dirent *dir_sd,
+static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
 			 const struct attribute_group *grp)
 {
 	struct attribute *const* attr;
+	int i;
 
-	for (attr = grp->attrs; *attr; attr++)
-		sysfs_hash_and_remove(dir_sd, (*attr)->name);
+	for (i = 0, attr = grp->attrs; *attr; i++, attr++)
+		if (!grp->is_visible ||
+		    grp->is_visible(kobj, *attr, i))
+			sysfs_hash_and_remove(dir_sd, (*attr)->name);
 }
 
-static int create_files(struct sysfs_dirent *dir_sd,
+static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
 			const struct attribute_group *grp)
 {
 	struct attribute *const* attr;
-	int error = 0;
+	int error = 0, i;
 
-	for (attr = grp->attrs; *attr && !error; attr++)
-		error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
+	for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++)
+		if (!grp->is_visible ||
+		    grp->is_visible(kobj, *attr, i))
+			error |=
+				sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
 	if (error)
-		remove_files(dir_sd, grp);
+		remove_files(dir_sd, kobj, grp);
 	return error;
 }
 
@@ -54,7 +60,7 @@ int sysfs_create_group(struct kobject * kobj,
 	} else
 		sd = kobj->sd;
 	sysfs_get(sd);
-	error = create_files(sd, grp);
+	error = create_files(sd, kobj, grp);
 	if (error) {
 		if (grp->name)
 			sysfs_remove_subdir(sd);
@@ -75,7 +81,7 @@ void sysfs_remove_group(struct kobject * kobj,
 	} else
 		sd = sysfs_get(dir_sd);
 
-	remove_files(sd, grp);
+	remove_files(sd, kobj, grp);
 	if (grp->name)
 		sysfs_remove_subdir(sd);
 
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 149ab62329e2..802710438a9e 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -32,6 +32,8 @@ struct attribute {
 
 struct attribute_group {
 	const char		*name;
+	int			(*is_visible)(struct kobject *,
+					      struct attribute *, int);
 	struct attribute	**attrs;
 };
 
diff --git a/kernel/params.c b/kernel/params.c
index 7686417ee00e..dfef46474e55 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -472,7 +472,7 @@ param_sysfs_setup(struct module_kobject *mk,
 			sizeof(mp->grp.attrs[0]));
 	size[1] = (valid_attrs + 1) * sizeof(mp->grp.attrs[0]);
 
-	mp = kmalloc(size[0] + size[1], GFP_KERNEL);
+	mp = kzalloc(size[0] + size[1], GFP_KERNEL);
 	if (!mp)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.20.1