sysfs: remove sysfs_addrm_cxt->parent_sd

sysfs_addrm_start/finish() enclose sysfs_dirent additions and
deletions and sysfs_addrm_cxt is used to record information necessary
to finish the operations.  Currently, sysfs_addrm_start() takes
@parent_sd, records it in sysfs_addrm_cxt, and assumes that all
operations in the block are performed under that @parent_sd.

This assumption has been fine until now but we want to make some
operations behave recursively and, while having @parent_sd recorded in
sysfs_addrm_cxt doesn't necessarily prevents that, it becomes
confusing.

This patch removes sysfs_addrm_cxt->parent_sd and makes
sysfs_add_one() take an explicit @parent_sd parameter.  Note that
sysfs_remove_one() doesn't need the extra argument as its parent is
always known from the target @sd.

While at it, add __acquires/releases() notations to
sysfs_addrm_start/finish() respectively.

This patch doesn't make any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 27 insertions, 25 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index d23e66dfba74..671868914b5b 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -406,22 +406,19 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 /**
  *      sysfs_addrm_start - prepare for sysfs_dirent add/remove
  *      @acxt: pointer to sysfs_addrm_cxt to be used
- *      @parent_sd: parent sysfs_dirent
  *
- *      This function is called when the caller is about to add or
- *      remove sysfs_dirent under @parent_sd.  This function acquires
- *      sysfs_mutex.  @acxt is used to keep and pass context to
- *      other addrm functions.
+ *      This function is called when the caller is about to add or remove
+ *      sysfs_dirent.  This function acquires sysfs_mutex.  @acxt is used
+ *      to keep and pass context to other addrm functions.
  *
  *      LOCKING:
  *      Kernel thread context (may sleep).  sysfs_mutex is locked on
  *      return.
  */
-void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
-                       struct sysfs_dirent *parent_sd)
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
+        __acquires(sysfs_mutex)
 {
         memset(acxt, 0, sizeof(*acxt));
-        acxt->parent_sd = parent_sd;
 
         mutex_lock(&sysfs_mutex);
 }
@@ -430,10 +427,11 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
  *      __sysfs_add_one - add sysfs_dirent to parent without warning
  *      @acxt: addrm context to use
  *      @sd: sysfs_dirent to be added
+ *      @parent_sd: the parent sysfs_dirent to add @sd to
  *
- *      Get @acxt->parent_sd and set sd->s_parent to it and increment
- *      nlink of parent inode if @sd is a directory and link into the
- *      children list of the parent.
+ *      Get @parent_sd and set @sd->s_parent to it and increment nlink of
+ *      the parent inode if @sd is a directory and link into the children
+ *      list of the parent.
  *
  *      This function should be called between calls to
  *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
@@ -446,20 +444,21 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
  *      0 on success, -EEXIST if entry with the given name already
  *      exists.
  */
-int __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,
+                    struct sysfs_dirent *parent_sd)
 {
         struct sysfs_inode_attrs *ps_iattr;
         int ret;
 
         sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-        sd->s_parent = sysfs_get(acxt->parent_sd);
+        sd->s_parent = sysfs_get(parent_sd);
 
         ret = sysfs_link_sibling(sd);
         if (ret)
                 return ret;
 
         /* Update timestamps on the parent */
-        ps_iattr = acxt->parent_sd->s_iattr;
+        ps_iattr = parent_sd->s_iattr;
         if (ps_iattr) {
                 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
                 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
@@ -493,10 +492,11 @@ static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
  *      sysfs_add_one - add sysfs_dirent to parent
  *      @acxt: addrm context to use
  *      @sd: sysfs_dirent to be added
+ *      @parent_sd: the parent sysfs_dirent to add @sd to
  *
- *      Get @acxt->parent_sd and set sd->s_parent to it and increment
- *      nlink of parent inode if @sd is a directory and link into the
- *      children list of the parent.
+ *      Get @parent_sd and set @sd->s_parent to it and increment nlink of
+ *      the parent inode if @sd is a directory and link into the children
+ *      list of the parent.
  *
  *      This function should be called between calls to
  *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
@@ -509,17 +509,18 @@ static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
  *      0 on success, -EEXIST if entry with the given name already
  *      exists.
  */
-int 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,
+                  struct sysfs_dirent *parent_sd)
 {
         int ret;
 
-        ret = __sysfs_add_one(acxt, sd);
+        ret = __sysfs_add_one(acxt, sd, parent_sd);
         if (ret == -EEXIST) {
                 char *path = kzalloc(PATH_MAX, GFP_KERNEL);
                 WARN(1, KERN_WARNING
                      "sysfs: cannot create duplicate filename '%s'\n",
                      (path == NULL) ? sd->s_name
-                                    : (sysfs_pathname(acxt->parent_sd, path),
+                                    : (sysfs_pathname(parent_sd, path),
                                        strlcat(path, "/", PATH_MAX),
                                        strlcat(path, sd->s_name, PATH_MAX),
                                        path));
@@ -553,7 +554,7 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
         sysfs_unlink_sibling(sd);
 
         /* Update timestamps on the parent */
-        ps_iattr = acxt->parent_sd->s_iattr;
+        ps_iattr = sd->s_parent->s_iattr;
         if (ps_iattr) {
                 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
                 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
@@ -576,6 +577,7 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
  *      sysfs_mutex is released.
  */
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
+        __releases(sysfs_mutex)
 {
         /* release resources acquired by sysfs_addrm_start() */
         mutex_unlock(&sysfs_mutex);
@@ -678,8 +680,8 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
         sd->s_dir.kobj = kobj;
 
         /* link in */
-        sysfs_addrm_start(&acxt, parent_sd);
-        rc = sysfs_add_one(&acxt, sd);
+        sysfs_addrm_start(&acxt);
+        rc = sysfs_add_one(&acxt, sd, parent_sd);
         sysfs_addrm_finish(&acxt);
 
         if (rc == 0)
@@ -772,7 +774,7 @@ static void remove_dir(struct sysfs_dirent *sd)
 {
         struct sysfs_addrm_cxt acxt;
 
-        sysfs_addrm_start(&acxt, sd->s_parent);
+        sysfs_addrm_start(&acxt);
         sysfs_remove_one(&acxt, sd);
         sysfs_addrm_finish(&acxt);
 }
@@ -792,7 +794,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
                 return;
 
         pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
-        sysfs_addrm_start(&acxt, dir_sd);
+        sysfs_addrm_start(&acxt);
         pos = rb_first(&dir_sd->s_dir.children);
         while (pos) {
                 struct sysfs_dirent *sd = to_sysfs_dirent(pos);