On Thu, Oct 26, 2023 at 11:35 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Fri, Oct 27, 2023, at 01:54, Kent Overstreet wrote: > > On Fri, Oct 27, 2023 at 01:05:48AM +0200, Thomas Gleixner wrote: > >> On Thu, Oct 26 2023 at 18:33, Suren Baghdasaryan wrote: > >> > On Wed, Oct 25, 2023 at 5:33 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > >> >> > This avoids a circular header dependency in an upcoming patch by only > >> >> > making hrtimer.h depend on percpu-defs.h > >> >> > >> >> What's the actual dependency problem? > >> > > >> > Sorry for the delay. > >> > When we instrument per-cpu allocations in [1] we need to include > >> > sched.h in percpu.h to be able to use alloc_tag_save(). sched.h > >> > >> Including sched.h in percpu.h is fundamentally wrong as sched.h is the > >> initial place of all header recursions. > >> > >> There is a reason why a lot of funtionalitiy has been split out of > >> sched.h into seperate headers over time in order to avoid that. > > > > Yeah, it's definitely unfortunate. The issue here is that > > alloc_tag_save() needs task_struct - we have to pull that in for > > alloc_tag_save() to be inline, which we really want. > > > > What if we moved task_struct to its own dedicated header? That might be > > good to do anyways... > > Yes, I agree that is the best way to handle it. I've prototyped > a more thorough header cleanup with good results (much improved > build speed) in the past, and most of the work to get there is > to seperate out structures like task_struct, mm_struct, net_device, > etc into headers that only depend on the embedded structure > definitions without needing all the inline functions associated > with them. This is something I'll add to our automation todos which I plan to talk about at plumbers; I feel like it should be possible to write a script that given a header and identifier can split whatever declaration out into a new header, update the old header, then add the necessary includes for the newly created header to each dependent (optional). -- Thanks, ~Nick Desaulniers
