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SubjectRe: [RFC][PATCH] debugfs: Fix corrupted loop in debugfs_remove_recursive
On Mon, Jun 09, 2014 at 02:06:07PM -0400, Steven Rostedt wrote:

> When these are called, the d_entry and inode locks need to be released
> to call the instance creation and deletion code. That code has its own
> accounting and locking to serialize everything to prevent multiple
> users from causing harm. As the parent "instance" directory can not
> be modified this simplifies things.

Yecchhh... Looking at debugfs:

static inline int debugfs_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}

...
if (debugfs_positive(dentry)) {
if (dentry->d_inode) {
What the hell?

parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;
Huh? First of all, ->d_parent is *never* NULL. Moreover, it can't be a
negative dentry.

What's more, if debugfs_rename() is ever used for cross-directory renames,
this tree-walker is buggered - it'll happily walk up "back" into a directory
it has never visited...


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