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Commit 154b9d75 authored by Nicolai Stange's avatar Nicolai Stange Committed by Greg Kroah-Hartman
Browse files

debugfs: call debugfs_real_fops() only after debugfs_file_get() 



The current implementation of debugfs_real_fops() relies on a
debugfs_fsdata instance to be installed at ->d_fsdata.

With future patches introducing lazy allocation of these, this requirement
will be guaranteed to be fullfilled only inbetween a
debugfs_file_get()/debugfs_file_put() pair.

The full proxies' fops implemented by debugfs happen to be the only
offenders. Fix them up by moving their debugfs_real_fops() calls past those
to debugfs_file_get().

full_proxy_release() is special as it doesn't invoke debugfs_file_get() at
all. Leave it alone for now.

Signed-off-by: default avatarNicolai Stange <nicstange@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c9afbec2

fs/debugfs/file.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -144,13 +144,13 @@ const struct file_operations debugfs_open_proxy_file_operations = { 
static ret_type full_proxy_ ## name(proto)				\

static ret_type full_proxy_ ## name(proto)				\

{									\

{									\

	struct dentry *dentry = F_DENTRY(filp);			\

	struct dentry *dentry = F_DENTRY(filp);			\

	const struct file_operations *real_fops =			\

	const struct file_operations *real_fops;			\

		debugfs_real_fops(filp);				\

	ret_type r;							\

	ret_type r;							\

									\

									\

	r = debugfs_file_get(dentry);					\

	r = debugfs_file_get(dentry);					\

	if (unlikely(r))						\

	if (unlikely(r))						\

		return r;						\

		return r;						\

	real_fops = debugfs_real_fops(filp);				\

	r = real_fops->name(args);					\

	r = real_fops->name(args);					\

	debugfs_file_put(dentry);					\

	debugfs_file_put(dentry);					\

	return r;							\

	return r;							\
@@ -177,13 +177,14 @@ FULL_PROXY_FUNC(unlocked_ioctl, long, filp, 
static unsigned int full_proxy_poll(struct file *filp,

static unsigned int full_proxy_poll(struct file *filp,

				struct poll_table_struct *wait)

				struct poll_table_struct *wait)

{

{

	const struct file_operations *real_fops = debugfs_real_fops(filp);

	struct dentry *dentry = F_DENTRY(filp);

	struct dentry *dentry = F_DENTRY(filp);

	unsigned int r = 0;

	unsigned int r = 0;

	const struct file_operations *real_fops;





	if (debugfs_file_get(dentry))

	if (debugfs_file_get(dentry))

		return POLLHUP;

		return POLLHUP;





	real_fops = debugfs_real_fops(filp);

	r = real_fops->poll(filp, wait);

	r = real_fops->poll(filp, wait);

	debugfs_file_put(dentry);

	debugfs_file_put(dentry);

	return r;

	return r;