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Commit 4d45f797 authored by Nicolai Stange's avatar Nicolai Stange Committed by Greg Kroah-Hartman
Browse files

debugfs: unproxify files created through debugfs_create_bool() 



Currently, the struct file_operations fops_bool associated with files
created through the debugfs_create_bool() helpers are not file
lifetime aware.

Thus, a lifetime managing proxy is created around fops_bool each time such
a file is opened which is an unnecessary waste of resources.

Implement file lifetime management for the fops_bool file_operations.
Namely, make debugfs_read_file_bool() and debugfs_write_file_bool() safe
against file removals by means of debugfs_use_file_start() and
debugfs_use_file_finish().

Make debugfs_create_bool() create its files in non-proxying operation mode
through debugfs_create_mode_unsafe().

Finally, purge debugfs_create_mode() as debugfs_create_bool() had been its
last user.

Signed-off-by: default avatarNicolai Stange <nicstange@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4909f168

fs/debugfs/file.c

+20 −21
Original line number Diff line number Diff line
@@ -312,22 +312,6 @@ ssize_t debugfs_attr_write(struct file *file, const char __user *buf, 
}

EXPORT_SYMBOL_GPL(debugfs_attr_write);



static struct dentry *debugfs_create_mode(const char *name, umode_t mode,

					  struct dentry *parent, void *value,

				          const struct file_operations *fops,

				          const struct file_operations *fops_ro,

				          const struct file_operations *fops_wo)

{

	/* if there are no write bits set, make read only */

	if (!(mode & S_IWUGO))

		return debugfs_create_file(name, mode, parent, value, fops_ro);

	/* if there are no read bits set, make write only */

	if (!(mode & S_IRUGO))

		return debugfs_create_file(name, mode, parent, value, fops_wo);



	return debugfs_create_file(name, mode, parent, value, fops);

}



static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode,

					struct dentry *parent, void *value,

					const struct file_operations *fops,
@@ -756,9 +740,17 @@ ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf, 
			       size_t count, loff_t *ppos)

{

	char buf[3];

	bool *val = file->private_data;

	bool val;

	int r, srcu_idx;



	if (*val)

	r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);

	if (likely(!r))

		val = *(bool *)file->private_data;

	debugfs_use_file_finish(srcu_idx);

	if (r)

		return r;



	if (val)

		buf[0] = 'Y';

	else

		buf[0] = 'N';
@@ -774,6 +766,7 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf, 
	char buf[32];

	size_t buf_size;

	bool bv;

	int r, srcu_idx;

	bool *val = file->private_data;



	buf_size = min(count, (sizeof(buf)-1));
@@ -781,8 +774,14 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf, 
		return -EFAULT;



	buf[buf_size] = '\0';

	if (strtobool(buf, &bv) == 0)

	if (strtobool(buf, &bv) == 0) {

		r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);

		if (likely(!r))

			*val = bv;

		debugfs_use_file_finish(srcu_idx);

		if (r)

			return r;

	}



	return count;

}
@@ -834,7 +833,7 @@ static const struct file_operations fops_bool_wo = { 
struct dentry *debugfs_create_bool(const char *name, umode_t mode,

				   struct dentry *parent, bool *value)

{

	return debugfs_create_mode(name, mode, parent, value, &fops_bool,

	return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool,

				   &fops_bool_ro, &fops_bool_wo);

}

EXPORT_SYMBOL_GPL(debugfs_create_bool);