From b4b7ff4b08e691656c9d77c758fc355833128ac0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 20 Jan 2016 14:01:31 -0300
Subject: Linux-libre 4.4-gnu

---
 fs/sysfs/file.c  |  4 +++-
 fs/sysfs/group.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 62 insertions(+), 3 deletions(-)

(limited to 'fs/sysfs')

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 6c95628ea..f35523d4f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -108,6 +108,7 @@ static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
 {
 	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
 	struct kobject *kobj = of->kn->parent->priv;
+	size_t len;
 
 	/*
 	 * If buf != of->prealloc_buf, we don't know how
@@ -115,7 +116,8 @@ static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
 	 */
 	if (pos || WARN_ON_ONCE(buf != of->prealloc_buf))
 		return 0;
-	return ops->show(kobj, of->kn->priv, buf);
+	len = ops->show(kobj, of->kn->priv, buf);
+	return min(count, len);
 }
 
 /* kernfs write callback for regular sysfs files */
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 39a019936..dc1358b5e 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;
 		}
@@ -352,3 +365,47 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
+
+/**
+ * __compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
+ * to a group or an attribute
+ * @kobj:		The kobject containing the group.
+ * @target_kobj:	The target kobject.
+ * @target_name:	The name of the target group or attribute.
+ */
+int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
+				      struct kobject *target_kobj,
+				      const char *target_name)
+{
+	struct kernfs_node *target;
+	struct kernfs_node *entry;
+	struct kernfs_node *link;
+
+	/*
+	 * We don't own @target_kobj and it may be removed at any time.
+	 * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
+	 * for details.
+	 */
+	spin_lock(&sysfs_symlink_target_lock);
+	target = target_kobj->sd;
+	if (target)
+		kernfs_get(target);
+	spin_unlock(&sysfs_symlink_target_lock);
+	if (!target)
+		return -ENOENT;
+
+	entry = kernfs_find_and_get(target_kobj->sd, target_name);
+	if (!entry) {
+		kernfs_put(target);
+		return -ENOENT;
+	}
+
+	link = kernfs_create_link(kobj->sd, target_name, entry);
+	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
+		sysfs_warn_dup(kobj->sd, target_name);
+
+	kernfs_put(entry);
+	kernfs_put(target);
+	return IS_ERR(link) ? PTR_ERR(link) : 0;
+}
+EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
-- 
cgit v1.2.3-54-g00ecf