Rusty Russell wrote:
> Hi all,
>
> Converting to and from void * for callback functions loses type safety:
> everywhere else we expect the compiler to catch incorrect pointer types
> handed to functions.
>
> It's pretty simple to create typesafe callback functions using typeof, and
> with a little gcc trickery we can allow both old-style and typesafe callbacks
> to avoid churn on commonly-used routines.
I wasn't too convinced with only irq handler conversion but with other
things converted, I'm liking it very much. I really like the timer
conversion as casting between void * and unsigned long is annoying.
Possible improvements.
* Passing NULL as data to callback which takes non-void pointer
triggers warning. I think this should be allowed. Something like
the following?
* Allowing non-pointer integral types which fit into pointer would be
nice. It's often convenient to pass integers to simple callbacks.
The following macro kinda-sorta achieves the above two but it doesn't
consider promotion of integer types and thus is too strict. There
gotta be some way.
#define kthread_create(threadfn, data, namefmt...) ({ \
int (*_threadfn)(typeof(data)); \
void *_data; \
_threadfn =
__builtin_choose_expr(!__builtin_types_compatible_p(typeof(data),
typeof(NULL)), \
(threadfn), (void *)(threadfn)); \
_data = __builtin_choose_expr(sizeof(data) <= sizeof(void *), \
(void *)(unsigned long)data, (void *)data); \
__kthread_create((void *)_threadfn, _data, namefmt); \
})
Thanks.
--
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
