#define GIANT_PROC 1
#define GIANT_FILE 2

extern int kern_giant_file;
extern int kern_giant_proc;
extern int _mtx_lock_giant(int);
extern void _mtx_unlock_giant(int);

#if defined(GIANT_PROC_ALWAYS) || defined(GIANT_ALL_ALWAYS)
#define _mtx_lock_proc(s) \
  if (!s) mtx_lock(&Giant); (s) |= GIANT_PROC
#define _mtx_unlock_proc(s) \
  if (s & GIANT_PROC) mtx_unlock(&Giant); (s) = 0
#elif defined(GIANT_PROC_NEVER) || defined(GIANT_ALL_NEVER)
#define _mtx_lock_proc(s) \
  do {} while (0)
#define _mtx_unlock_proc(s) \
  do {} while (0); (s) = 0
#else
#define _mtx_lock_proc(s) \
  (s) |= _mtx_lock_giant(kern_giant_proc)
#define _mtx_unlock_proc(s) \
  if (s) _mtx_unlock_giant(s); (s) = 0
#endif
/* and so on for the other flags for other bits */
#if defined(GIANT_FILE_ALWAYS) || defined(GIANT_ALL_ALWAYS)
#define _mtx_lock_file(s) \
  if (!s) mtx_lock(&Giant); (s) |= GIANT_FILE
#define _mtx_unlock_file(s) \
  if (s & GIANT_FILE) mtx_unlock(&Giant); (s) = 0
#elif defined(GIANT_FILE_NEVER) || defined(GIANT_ALL_NEVER)
#define _mtx_lock_file(s) \
  do {} while (0)
#define _mtx_unlock_file(s) \
  do {} while (0); (s) = 0
#else
#define _mtx_lock_file(s) \
  (s) |= _mtx_lock_giant(kern_giant_file)
#define _mtx_unlock_file(s) \
  if (s) _mtx_unlock_giant(s); (s) = 0
#endif
	
#define mtx_lock_giant(mask) \
  ({ \
      int ret = 0; \
      if (mask & GIANT_PROC) { \
          _mtx_lock_proc(ret); \
      } else if (mask & GIANT_FILE) { \
          _mtx_lock_file(ret); \
      } else \
          panic("unknown flag"); \
      ret; \
  })

#if 0	/* bah, gcc isn't smart enough for this yet */
#define mtx_unlock_giant(mask) \
{ \
	if (mask & GIANT_PROC) { \
	    _mtx_unlock_proc(mask); \
	} else if (mask & GIANT_FILE) { \
	    _mtx_unlock_file(mask); \
	} \
}
#else
#define mtx_unlock_giant(mask) \
{ \
	if (mask) \
		_mtx_unlock_giant(mask); \
}
#endif

/* hackery to get basic stuff to compile */
int Giant;
extern void bar(void);
extern void mtx_lock(int *);
extern void mtx_unlock(int *);

void
foo(void)
{
	int q;

	q = mtx_lock_giant(GIANT_PROC);
	bar();
	if (q) mtx_unlock_giant(q);
}