debugfs: unproxify files created through debugfs_create_u32_array()

BugLink: https://bugs.launchpad.net/bugs/1884159

The struct file_operations u32_array_fops associated with files created
through debugfs_create_u32_array() has been lifetime aware already:
everything needed for subsequent operation is copied to a ->f_private
buffer at file opening time in u32_array_open(). Now, ->open() is always
protected against file removal issues by the debugfs core.

There is no need for the debugfs core to wrap the u32_array_fops
with a file lifetime managing proxy.

Make debugfs_create_u32_array() create its files in non-proxying operation
mode by means of debugfs_create_file_unsafe().
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit c4a74f63)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

fs/debugfs/file.c

@@ -992,7 +992,8 @@ struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
 	data->array = array;
 	data->elements = elements;
 
-	return debugfs_create_file(name, mode, parent, data, &u32_array_fops);
+	return debugfs_create_file_unsafe(name, mode, parent, data,
+					&u32_array_fops);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_u32_array);