The "__stringify ()" Macro definition in Linux system is detailed __linux

Include/linux/stringify.h:

#ifndef __linux_stringify_h
#define __LINUX_STRINGIFY_H/

* Indirect stringification.  Doing two levels allows the parameter to be a
 * macro itself.  For example, compile With-dfoo=bar, __stringify (FOO)
 * converts to "bar".
 * *

#define __STRINGIFY_1 (x ...) #x
#define __STRINGIFY (x.   ) __stringify_1 (x)

#endif/  *!__linux_stringify_h * *

Look at the source code above,

__stringify (x ...) the actual expansion of this macro is: #x

The effect is actually to convert x directly into a string. The return value is the string, not the variable name.

Such as

   #define __ATTR (_name,_mode,_show,_store) {/
     . ATTR = {. Name = __stringify (_name),. Mode = _mode},/
     . Show = _sh ow,     /
     . store = _store,     /
    }

Suppose we use __attr this way:

__attr (Var_name, 777, show_function, store_function)

The value that is actually copied to. Attr.name is "Var_name", not the value represented by the Var_name variable.