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
