[PATCH] sysfs: fix problem with duplicate sysfs directories and files

The following patch checks for existing sysfs_dirent before
preparing new one while creating sysfs directories and files.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 31 insertions, 1 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index cfd290d3d6b..bea1f4c02b9 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -50,6 +50,32 @@ static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * parent_sd,
 	return sd;
 }
 
+/**
+ *
+ * Return -EEXIST if there is already a sysfs element with the same name for
+ * the same parent.
+ *
+ * called with parent inode's i_mutex held
+ */
+int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
+			  const unsigned char *new)
+{
+	struct sysfs_dirent * sd;
+
+	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+		if (sd->s_element) {
+			const unsigned char *existing = sysfs_get_name(sd);
+			if (strcmp(existing, new))
+				continue;
+			else
+				return -EEXIST;
+		}
+	}
+
+	return 0;
+}
+
+
 int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
 			void * element, umode_t mode, int type)
 {
@@ -102,7 +128,11 @@ static int create_dir(struct kobject * k, struct dentry * p,
 	mutex_lock(&p->d_inode->i_mutex);
 	*d = lookup_one_len(n, p, strlen(n));
 	if (!IS_ERR(*d)) {
-		error = sysfs_make_dirent(p->d_fsdata, *d, k, mode, SYSFS_DIR);
+ 		if (sysfs_dirent_exist(p->d_fsdata, n))
+  			error = -EEXIST;
+  		else
+			error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
+								SYSFS_DIR);
 		if (!error) {
 			error = sysfs_create(*d, mode, init_dir);
 			if (!error) {