linux-kernel - Re: [PATCH 04/13] mm: Fix pmd_read

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Message-ID: <Y2EUEBlQXNgaJgoI@hirez.programming.kicks-ass.net>
Date:   Tue, 1 Nov 2022 13:41:52 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     x86@...nel.org, willy@...radead.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        aarcange@...hat.com, kirill.shutemov@...ux.intel.com,
        jroedel@...e.de, ubizjak@...il.com
Subject: Re: [PATCH 04/13] mm: Fix pmd_read_atomic()

On Sat, Oct 22, 2022 at 10:30:51AM -0700, Linus Torvalds wrote:
> On Sat, Oct 22, 2022 at 4:48 AM Peter Zijlstra <peterz@...radead.org> wrote:
> >
> > --- a/include/linux/pgtable.h
> > +++ b/include/linux/pgtable.h
> > @@ -258,6 +258,13 @@ static inline pte_t ptep_get(pte_t *ptep
> >  }
> >  #endif
> >
> > +#ifndef __HAVE_ARCH_PMDP_GET
> > +static inline pmd_t pmdp_get(pmd_t *pmdp)
> > +{
> > +       return READ_ONCE(*pmdp);
> > +}
> > +#endif
> 
> What, what, what?
> 
> Where did that __HAVE_ARCH_PMDP_GET come from?
> 
> I'm not seeing it #define'd anywhere, and we _really_ shouldn't be
> doing this any more.
> 
> Please just do
> 
>     #ifndef pmdp_get
>     static inline pmd_t pmdp_get(pmd_t *pmdp)
>     ..
> 
> and have the architectures that do their own pmdp_get(), just have that
> 
>    #define pmdp_get pmdp_get
> 
> to let the generic code know about it. Instead of making up a new
> __HAVE_ARCH_XYZ name.

So I've stuck the below on. There's a *TON* more to convert and I'm not
going to be doing that just now (seems like a clever enough script
should be able to), but this gets rid of the new one I introduced.

---

Subject: mm: Convert __HAVE_ARCH_P..P_GET to the new style
From: Peter Zijlstra <peterz@...radead.org>
Date: Tue Nov  1 12:53:18 CET 2022

Since __HAVE_ARCH_* style guards have been depricated in favour of
defining the function name onto itself, convert pxxp_get().

Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/powerpc/include/asm/nohash/32/pgtable.h |    2 +-
 include/linux/pgtable.h                      |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -263,7 +263,7 @@ static inline pte_basic_t pte_update(str
 }
 
 #ifdef CONFIG_PPC_16K_PAGES
-#define __HAVE_ARCH_PTEP_GET
+#define ptep_get ptep_get
 static inline pte_t ptep_get(pte_t *ptep)
 {
	pte_basic_t val = READ_ONCE(ptep->pte);
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -291,14 +291,14 @@ static inline void ptep_clear(struct mm_
	ptep_get_and_clear(mm, addr, ptep);
 }
 
-#ifndef __HAVE_ARCH_PTEP_GET
+#ifndef ptep_get
 static inline pte_t ptep_get(pte_t *ptep)
 {
	return READ_ONCE(*ptep);
 }
 #endif
 
-#ifndef __HAVE_ARCH_PMDP_GET
+#ifndef pmdp_get
 static inline pmd_t pmdp_get(pmd_t *pmdp)
 {
	return READ_ONCE(*pmdp);