Messages in this thread |  | | Date | Thu, 20 Oct 2016 08:40:45 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/3] sched/core,x86: make struct thread_info arch specific again |
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* Andy Lutomirski <luto@amacapital.net> wrote:
> On Wed, Oct 19, 2016 at 11:28 AM, Mark Rutland <mark.rutland@arm.com> wrote: > > From: Heiko Carstens <heiko.carstens@de.ibm.com> > > > > commit c65eacbe290b ("sched/core: Allow putting thread_info into > > task_struct") made struct thread_info a generic struct with only a > > single flags member if THREAD_INFO_IN_TASK_STRUCT is selected. > > > > This change however seems to be quite x86 centric, since at least the > > generic preemption code (asm-generic/preempt.h) assumes that struct > > thread_info also has a preempt_count member, which apparently was not > > true for x86. > > > > We could add a bit more ifdefs to solve this problem too, but it seems > > to be much simpler to make struct thread_info arch specific > > again. This also makes the conversion to THREAD_INFO_IN_TASK_STRUCT a > > bit easier for architectures that have a couple of arch specific stuff > > in their thread_info definition. > > > > The arch specific stuff _could_ be moved to thread_struct. However > > keeping them in thread_info makes it easier: accessing thread_info > > members is simple, since it is at the beginning of the task_struct, > > while the thread_struct is at the end. At least on s390 the offsets > > needed to access members of the thread_struct (with task_struct as > > base) are too large for various asm instructions. This is not a > > problem when keeping these members within thread_info. > > Acked-by: Andy Lutomirski <luto@kernel.org> > > Ingo, there's a (somewhat weak) argument for sending this via > tip/urgent: it doesn't change generated code at all, and I think it > will avoid a silly depedency or possible conflict for the next merge > window, since both arm64 and s390 are going to need it.
Can certainly do it if this is the final version of the patch. Mark?
Thanks,
Ingo
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