sysfs: implement sysfs_dirent active reference and immediate disconnect

[powerpc.git] / fs / sysfs / dir.c

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2a94dc3..e0d377a 100644 (file)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -53,6 +53,19 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
  repeat:
        parent_sd = sd->s_parent;
 
+       /* If @sd is being released after deletion, s_active is write
+        * locked.  If @sd is cursor for directory walk or being
+        * released prematurely, s_active has no reader or writer.
+        *
+        * sysfs_deactivate() lies to lockdep that s_active is
+        * unlocked immediately.  Lie one more time to cover the
+        * previous lie.
+        */
+       if (!down_write_trylock(&sd->s_active))
+               rwsem_acquire(&sd->s_active.dep_map,
+                             SYSFS_S_ACTIVE_DEACTIVATE, 0, _RET_IP_);
+       up_write(&sd->s_active);
+
        if (sd->s_type & SYSFS_KOBJ_LINK)
                sysfs_put(sd->s_elem.symlink.target_sd);
        if (sd->s_type & SYSFS_COPY_NAME)
@@ -113,6 +126,7 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 
        atomic_set(&sd->s_count, 1);
        atomic_set(&sd->s_event, 1);
+       init_rwsem(&sd->s_active);
        INIT_LIST_HEAD(&sd->s_children);
        INIT_LIST_HEAD(&sd->s_sibling);
 
@@ -371,7 +385,6 @@ static void remove_dir(struct dentry * d)
        d_delete(d);
        sd = d->d_fsdata;
        list_del_init(&sd->s_sibling);
-       sysfs_put(sd);
        if (d->d_inode)
                simple_rmdir(parent->d_inode,d);
 
@@ -380,6 +393,9 @@ static void remove_dir(struct dentry * d)
 
        mutex_unlock(&parent->d_inode->i_mutex);
        dput(parent);
+
+       sysfs_deactivate(sd);
+       sysfs_put(sd);
 }
 
 void sysfs_remove_subdir(struct dentry * d)
@@ -390,6 +406,7 @@ void sysfs_remove_subdir(struct dentry * d)
 
 static void __sysfs_remove_dir(struct dentry *dentry)
 {
+       LIST_HEAD(removed);
        struct sysfs_dirent * parent_sd;
        struct sysfs_dirent * sd, * tmp;
 
@@ -403,12 +420,17 @@ static void __sysfs_remove_dir(struct dentry *dentry)
        list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
                if (!sd->s_type || !(sd->s_type & SYSFS_NOT_PINNED))
                        continue;
-               list_del_init(&sd->s_sibling);
+               list_move(&sd->s_sibling, &removed);
                sysfs_drop_dentry(sd, dentry);
-               sysfs_put(sd);
        }
        mutex_unlock(&dentry->d_inode->i_mutex);
 
+       list_for_each_entry_safe(sd, tmp, &removed, s_sibling) {
+               list_del_init(&sd->s_sibling);
+               sysfs_deactivate(sd);
+               sysfs_put(sd);
+       }
+
        remove_dir(dentry);
        /**
         * Drop reference from dget() on entrance.