[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 cfd290d3d6b1..bea1f4c02b9b 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) {