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Diffstat (limited to 'fs/debugfs/inode.c')
-rw-r--r--fs/debugfs/inode.c33
1 files changed, 26 insertions, 7 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 8c41b52da358..16a46b6a6fee 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -534,7 +534,7 @@ EXPORT_SYMBOL_GPL(debugfs_remove);
*/
void debugfs_remove_recursive(struct dentry *dentry)
{
- struct dentry *child, *next, *parent;
+ struct dentry *child, *parent;
if (IS_ERR_OR_NULL(dentry))
return;
@@ -546,30 +546,49 @@ void debugfs_remove_recursive(struct dentry *dentry)
parent = dentry;
down:
mutex_lock(&parent->d_inode->i_mutex);
- list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
+ loop:
+ /*
+ * The parent->d_subdirs is protected by the d_lock. Outside that
+ * lock, the child can be unlinked and set to be freed which can
+ * use the d_u.d_child as the rcu head and corrupt this list.
+ */
+ spin_lock(&parent->d_lock);
+ list_for_each_entry(child, &parent->d_subdirs, d_u.d_child) {
if (!debugfs_positive(child))
continue;
/* perhaps simple_empty(child) makes more sense */
if (!list_empty(&child->d_subdirs)) {
+ spin_unlock(&parent->d_lock);
mutex_unlock(&parent->d_inode->i_mutex);
parent = child;
goto down;
}
- up:
+
+ spin_unlock(&parent->d_lock);
+
if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+
+ /*
+ * The parent->d_lock protects agaist child from unlinking
+ * from d_subdirs. When releasing the parent->d_lock we can
+ * no longer trust that the next pointer is valid.
+ * Restart the loop. We'll skip this one with the
+ * debugfs_positive() check.
+ */
+ goto loop;
}
+ spin_unlock(&parent->d_lock);
mutex_unlock(&parent->d_inode->i_mutex);
child = parent;
parent = parent->d_parent;
mutex_lock(&parent->d_inode->i_mutex);
- if (child != dentry) {
- next = list_next_entry(child, d_u.d_child);
- goto up;
- }
+ if (child != dentry)
+ /* go up */
+ goto loop;
if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count);