Re: Casting away noderef and address spaces?

[Rusty Russell <rusty@rustcorp.com.au>]

On Tuesday 23 December 2008 07:27:50 Al Viro wrote:
> The right solution is
> 	(*(typeof(v) __attribute__((address_space(0), force)) *)(&v))
> 
> Cast there will take a pointer to type of V and force-cast it to pointer to
> unqualified type of V.  *(cast)&v will do the obvious thing.  Will trim
> both the AS and noderef.

Thanks Al, that worked, but seems to tickle another bug (sparse 0.4.1, Ubuntu).

rusty@vivaldi:/tmp$ sparse foo.c
foo.c:11:20: warning: incorrect type in assignment (invalid types)
foo.c:11:20:    expected unknown type 11<noident>
foo.c:11:20:    got int

Here's my sample program now:

#define __percpu __attribute__((noderef, address_space(3)))

/* Turn v back into a normal var. */
#define convert(v) \
        (*(typeof(v) __attribute__((address_space(0), force)) *)(&v))

int main(int argc, char *argv)
{
        unsigned int __percpu x;

        convert(x) = 0;
        return 0;
}