On Fri, Nov 19, 2021 at 04:06:27PM +0100, Alejandro Colomar (man-pages) wrote: > Hi Arnd, > > On 11/19/21 15:47, Arnd Bergmann wrote: > > On Fri, Nov 19, 2021 at 12:36 PM Alejandro Colomar > > <alx.manpages@xxxxxxxxx> wrote: > >> > >> Alejandro Colomar (17): > >> linux/container_of.h: Add memberof(T, m) > >> Use memberof(T, m) instead of explicit NULL dereference > >> Replace some uses of memberof() by its wrappers > >> linux/memberof.h: Move memberof() to separate header > >> linux/typeof_member.h: Move typeof_member() to a separate header > >> Simplify sizeof(typeof_member()) to sizeof_field() > >> linux/NULL.h: Move NULL to a separate header > >> linux/offsetof.h: Move offsetof(T, m) to a separate header > >> linux/offsetof.h: Implement offsetof() in terms of memberof() > >> linux/container_of.h: Implement container_of_safe() in terms of > >> container_of() > >> linux/container_of.h: Cosmetic > >> linux/container_of.h: Remove unnecessary cast to (void *) > > > > My feeling is that this takes the separation too far: by having this many header > > files that end up being included from practically every single .c file > > in the kernel, > > I think you end up making compile speed worse overall. > > > > If your goal is to avoid having to recompile as much of the kernel > > after touching > > a header, I think a better approach is to help untangle the dependencies, e.g. > > by splitting out type definitions from headers with inline functions (most > > indirect header dependencies are on type definitions) and by focusing on > > linux/fs.h, linux/sched.h, linux/mm.h and how they interact with the rest of the > > headers. At the moment, these are included in most .c files and they in turn > > include a ton of other headers. > > Yes, I would like to untangle the dependencies. > > The main reason I started doing this splitting > is because I wouldn't be able to include > <linux/stddef.h> in some headers, > because it pulled too much stuff that broke unrelated things. > > So that's why I started from there. > > I for example would like to get NULL in memberof() > without puling anything else, > so <linux/NULL.h> makes sense for that. I don't believe that the code that uses NULL won't include types.h. -- With Best Regards, Andy Shevchenko
