Re: [PATCH 3/5] driver core: make struct device_type.uevent() take a const *

Greg Kroah-Hartman
2022-11-23T18:14:52Z

On Wed, Nov 23, 2022 at 05:49:36PM +0000, Matthew Wilcox wrote:
> On Wed, Nov 23, 2022 at 01:29:56PM -0400, Jason Gunthorpe wrote:
> > #define generic_container_of(in_type, in, out_type, out_member) \
> > _Generic(in, \
> > const in_type *: ((const out_type *)container_of(in, out_type, out_member)), \
> > in_type *: ((out_type *)container_of(in, out_type, out_member)) \
> > )
>
> There's a neat trick I found in seqlock.h:
>
> #define generic_container_of(in_t, in, out_t, m) \
> _Generic(*(in), \
> const in_t: ((const out_t *)container_of(in, out_t, m)), \
> in_t: ((out_t *)container_of(in, out_type, m)) \
> )
>
> and now it fits in 80 columns ;-)

Nice trick! Dropping the inline functions is a bit different, let me
see if that still gives a sane error if we pass an incorrect type or
mess with the const * the wrong way. I'll run some tests tomorrow
afternoon...

thanks,

greg k-h