On Wed, Nov 23, 2022 at 06:00:23PM +0000, Matthew Wilcox wrote:
On Wed, Nov 23, 2022 at 01:55:42PM -0400, Jason Gunthorpe wrote:
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 ;-)
Aside from less letters, is their another benifit to using *(in) ?
I don't think so. It just looks nicer to me than putting the star in each case. If I'd thought of it, I would have done it to page_folio(), but I won't change it now.
Ah, but your trick will not work, that blows up and will not build. The original one from Jason here does work. _Generic is tricky...
thanks,
greg k-h