[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>

4 files changed, 39 insertions, 5 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) {
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index e21f4022feb8..5e83e7246788 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -361,10 +361,12 @@ int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
 {
         struct sysfs_dirent * parent_sd = dir->d_fsdata;
         umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
-        int error = 0;
+        int error = -EEXIST;
 
         mutex_lock(&dir->d_inode->i_mutex);
-        error = sysfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
+        if (!sysfs_dirent_exist(parent_sd, attr->name))
+                error = sysfs_make_dirent(parent_sd, NULL, (void *)attr,
+                                          mode, type);
         mutex_unlock(&dir->d_inode->i_mutex);
 
         return error;
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index e38d6338a20d..fe23f47f6e43 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -82,12 +82,13 @@ exit1:
 int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name)
 {
         struct dentry * dentry = kobj->dentry;
-        int error = 0;
+        int error = -EEXIST;
 
         BUG_ON(!kobj || !kobj->dentry || !name);
 
         mutex_lock(&dentry->d_inode->i_mutex);
-        error = sysfs_add_link(dentry, name, target);
+        if (!sysfs_dirent_exist(dentry->d_fsdata, name))
+                error = sysfs_add_link(dentry, name, target);
         mutex_unlock(&dentry->d_inode->i_mutex);
         return error;
 }
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 3f8953e0e5d0..cf11d5b789d9 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -5,6 +5,7 @@ extern kmem_cache_t *sysfs_dir_cachep;
 extern struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent *);
 extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));
 
+extern int sysfs_dirent_exist(struct sysfs_dirent *, const unsigned char *);
 extern int sysfs_make_dirent(struct sysfs_dirent *, struct dentry *, void *,
                                 umode_t, int);