Re: [RFC PATCH 2/2] mm: mmu_notifier fix for tlb_end_vma (build failures)

[Guenter Roeck <linux@roeck-us.net>]

On Fri, Aug 24, 2018 at 02:50:48PM +0100, Will Deacon wrote:
> > 
> > Sorry, I was a bit quick of the mark there. You'll need a forward
> > declaration for the paramater type. Here it is with a commit message,
> > although still untested because I haven't got round to setting up a riscv
> > toolchain yet.
> > 

Still doesn't work.

CC      mm/memory.o
In file included from ./arch/riscv/include/asm/pgtable.h:26:0,
                 from ./include/linux/memremap.h:7,
		 from ./include/linux/mm.h:27,
		 from arch/riscv/mm/fault.c:23:
./arch/riscv/include/asm/tlb.h: In function ‘tlb_flush’:
./arch/riscv/include/asm/tlb.h:21:18: error:
	dereferencing pointer to incomplete type ‘struct mmu_gather’ flush_tlb_mm(tlb->mm);

Problem is that struct mmu_gather is dereferenced in tlb_flush().

Guenter

> > Will
> > 
> > --->8
> > 
> > From adb9be33d68320edcda80d540a97a647792894d2 Mon Sep 17 00:00:00 2001
> > From: Will Deacon <will.deacon@arm.com>
> > Date: Fri, 24 Aug 2018 14:33:48 +0100
> > Subject: [PATCH] riscv: tlb: Provide definition of tlb_flush() before
> >  including tlb.h
> > 
> > As of commit fd1102f0aade ("mm: mmu_notifier fix for tlb_end_vma"),
> > asm-generic/tlb.h now calls tlb_flush() from a static inline function,
> > so we need to make sure that it's declared before #including the
> > asm-generic header in the arch header.
> > 
> > Since tlb_flush() is a one-liner for riscv, we can define it before
> > including asm-generic/tlb.h as long as we provide a forward declaration
> > of struct mmu_gather.
> > 
> > Reported-by: Guenter Roeck <linux@roeck-us.net>
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
> > ---
> >  arch/riscv/include/asm/tlb.h | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/include/asm/tlb.h b/arch/riscv/include/asm/tlb.h
> > index c229509288ea..a3d1380ad970 100644
> > --- a/arch/riscv/include/asm/tlb.h
> > +++ b/arch/riscv/include/asm/tlb.h
> > @@ -14,11 +14,13 @@
> >  #ifndef _ASM_RISCV_TLB_H
> >  #define _ASM_RISCV_TLB_H
> >  
> > -#include <asm-generic/tlb.h>
> > +struct mmu_gather;
> >  
> >  static inline void tlb_flush(struct mmu_gather *tlb)
> >  {
> >  	flush_tlb_mm(tlb->mm);
> 
> Bah, didn't spot the dereference so this won't work either. You basically
> just need to copy what I did for arm64 in d475fac95779.
> 
> Will