sysfs: make sysfs_add_one() automatically check for duplicate entry

Make sysfs_add_one() check for duplicate entry and return -EEXIST if
such entry exists.  This simplifies node addition code a bit.

This patch doesn't introduce any noticeable behavior change.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 26 insertions, 23 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 354675ad096..620603296c6 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -491,9 +491,16 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
  *
  *      LOCKING:
  *      Determined by sysfs_addrm_start().
+ *
+ *      RETURNS:
+ *      0 on success, -EEXIST if entry with the given name already
+ *      exists.
  */
-void sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 {
+        if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
+                return -EEXIST;
+
         sd->s_parent = sysfs_get(acxt->parent_sd);
 
         if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
@@ -502,6 +509,8 @@ void sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
         acxt->cnt++;
 
         sysfs_link_sibling(sd);
+
+        return 0;
 }
 
 /**
@@ -691,6 +700,7 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
         struct sysfs_addrm_cxt acxt;
         struct sysfs_dirent *sd;
+        int rc;
 
         /* allocate */
         sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
@@ -700,17 +710,15 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 
         /* link in */
         sysfs_addrm_start(&acxt, parent_sd);
+        rc = sysfs_add_one(&acxt, sd);
+        sysfs_addrm_finish(&acxt);
 
-        if (!sysfs_find_dirent(parent_sd, name))
-                sysfs_add_one(&acxt, sd);
-
-        if (!sysfs_addrm_finish(&acxt)) {
+        if (rc == 0)
+                *p_sd = sd;
+        else
                 sysfs_put(sd);
-                return -EEXIST;
-        }
 
-        *p_sd = sd;
-        return 0;
+        return rc;
 }
 
 int sysfs_create_subdir(struct kobject *kobj, const char *name,
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index ea0e494d7d5..33bb3406dc4 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -397,6 +397,7 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
         umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
         struct sysfs_addrm_cxt acxt;
         struct sysfs_dirent *sd;
+        int rc;
 
         sd = sysfs_new_dirent(attr->name, mode, type);
         if (!sd)
@@ -404,16 +405,13 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
         sd->s_elem.attr.attr = (void *)attr;
 
         sysfs_addrm_start(&acxt, dir_sd);
+        rc = sysfs_add_one(&acxt, sd);
+        sysfs_addrm_finish(&acxt);
 
-        if (!sysfs_find_dirent(dir_sd, attr->name))
-                sysfs_add_one(&acxt, sd);
-
-        if (!sysfs_addrm_finish(&acxt)) {
+        if (rc)
                 sysfs_put(sd);
-                return -EEXIST;
-        }
 
-        return 0;
+        return rc;
 }
 
 
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index c129f307936..a6b13f12b0e 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -91,14 +91,11 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
         target_sd = NULL;       /* reference is now owned by the symlink */
 
         sysfs_addrm_start(&acxt, parent_sd);
+        error = sysfs_add_one(&acxt, sd);
+        sysfs_addrm_finish(&acxt);
 
-        if (!sysfs_find_dirent(parent_sd, name))
-                sysfs_add_one(&acxt, sd);
-
-        if (!sysfs_addrm_finish(&acxt)) {
-                error = -EEXIST;
+        if (error)
                 goto out_put;
-        }
 
         return 0;
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 32b8b64e5cf..bb3f0c999b1 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -62,7 +62,7 @@ extern struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
 extern void sysfs_put_active_two(struct sysfs_dirent *sd);
 extern void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
                               struct sysfs_dirent *parent_sd);
-extern void sysfs_add_one(struct sysfs_addrm_cxt *acxt,
+extern int sysfs_add_one(struct sysfs_addrm_cxt *acxt,
                           struct sysfs_dirent *sd);
 extern void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
                              struct sysfs_dirent *sd);