1 files changed, 28 insertions, 9 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 35a36d3..e6bb9b2 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -132,6 +132,24 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
 }
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+/* Test for attributes that want to ignore lockdep for read-locking */
+static bool ignore_lockdep(struct sysfs_dirent *sd)
+{
+	return sysfs_type(sd) == SYSFS_KOBJ_ATTR &&
+			sd->s_attr.attr->ignore_lockdep;
+}
+
+#else
+
+static inline bool ignore_lockdep(struct sysfs_dirent *sd)
+{
+	return true;
+}
+
+#endif
+
 /**
  *	sysfs_get_active - get an active reference to sysfs_dirent
  *	@sd: sysfs_dirent to get an active reference to
@@ -155,15 +173,17 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
 			return NULL;
 
 		t = atomic_cmpxchg(&sd->s_active, v, v + 1);
-		if (likely(t == v)) {
-			rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
-			return sd;
-		}
+		if (likely(t == v))
+			break;
 		if (t < 0)
 			return NULL;
 
 		cpu_relax();
 	}
+
+	if (likely(!ignore_lockdep(sd)))
+		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
+	return sd;
 }
 
 /**
@@ -180,7 +200,8 @@ void sysfs_put_active(struct sysfs_dirent *sd)
 	if (unlikely(!sd))
 		return;
 
-	rwsem_release(&sd->dep_map, 1, _RET_IP_);
+	if (likely(!ignore_lockdep(sd)))
+		rwsem_release(&sd->dep_map, 1, _RET_IP_);
 	v = atomic_dec_return(&sd->s_active);
 	if (likely(v != SD_DEACTIVATED_BIAS))
 		return;
@@ -858,7 +879,6 @@ int sysfs_rename(struct sysfs_dirent *sd,
 	struct sysfs_dirent *new_parent_sd, const void *new_ns,
 	const char *new_name)
 {
-	const char *dup_name = NULL;
 	int error;
 
 	mutex_lock(&sysfs_mutex);
@@ -875,11 +895,11 @@ int sysfs_rename(struct sysfs_dirent *sd,
 	/* rename sysfs_dirent */
 	if (strcmp(sd->s_name, new_name) != 0) {
 		error = -ENOMEM;
-		new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
+		new_name = kstrdup(new_name, GFP_KERNEL);
 		if (!new_name)
 			goto out;
 
-		dup_name = sd->s_name;
+		kfree(sd->s_name);
 		sd->s_name = new_name;
 	}
 
@@ -895,7 +915,6 @@ int sysfs_rename(struct sysfs_dirent *sd,
 	error = 0;
  out:
 	mutex_unlock(&sysfs_mutex);
-	kfree(dup_name);
 	return error;
 }