linux-kernel - Re: [PATCH v4 12/16] parisc: mm: Convert to GENERIC

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Message-ID: <Y/XTvJRtZXKa6b/M@MiWiFi-R3L-srv>
Date:   Wed, 22 Feb 2023 16:35:08 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Arnd Bergmann <arnd@...db.de>
Cc:     Matthew Wilcox <willy@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@...radead.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        David Laight <David.Laight@...lab.com>,
        Stafford Horne <shorne@...il.com>,
        "James E . J . Bottomley" <James.Bottomley@...senpartnership.com>,
        Helge Deller <deller@....de>,
        "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>
Subject: Re: [PATCH v4 12/16] parisc: mm: Convert to GENERIC_IOREMAP

Hi Christophe, Arnd,

On 02/17/23 at 01:46pm, Christophe Leroy wrote:
> 
> 
> Le 17/02/2023 à 14:31, Baoquan He a écrit :
> > On 02/16/23 at 04:18pm, Arnd Bergmann wrote:
> >> On Thu, Feb 16, 2023, at 16:02, Baoquan He wrote:
> >>> On 02/16/23 at 01:50pm, Matthew Wilcox wrote:
> >>> It's not if including asm-generic/iomap.h. The ARCH_HAS_IOREMAP_xx is to
> >>> avoid redefinition there.
> >>>
> >>> include/asm-generic/iomap.h:
> >>> ----
> >>> #ifndef ARCH_HAS_IOREMAP_WC
> >>> #define ioremap_wc ioremap
> >>> #endif
> >>
> >> I'd change that to the usual '#ifndef ioremap_wc' in that case.
> > 
> > Not sure if I got you. Kill all ARCH_HAS_IOREMAP_xxx in kernel? If yes,
> > sounds like a good idea.
> > 
> 
> At least kill that one at the first place in your series, and then the 
> other ones in a follow-up series maybe.

I made a patch to remove all ARCH_HAS_IOREMAP_xx macros in architectures
and the ifdeffery of ARCH_HAS_IOREMAP_xx in asm-generic/iomap.h.
But the change will cause building error as below. Becuase we usually
have '#include <asm-generic/iomap.h>' at the beginning of
arch/xx/include/asm/io.h, and have '#include <asm-generic/io.h>' at the
end of arch/xx/include/asm/io.h. For architecutres which has
ARCH_HAS_IOREMAP_xx defining, we need move ''#include <asm-generic/iomap.h>
dowe to below '#include <asm-generic/io.h>'. Please help check if it's
still worth doing.


***move '#include <asm-generic/iomap.h>' below '#include <asm-generic/io.h>' 
***
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 8ab68cde1f13..a8d55fc62959 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -209,8 +209,6 @@ void memset_io(volatile void __iomem *, int, size_t);
 #define memcpy_toio memcpy_toio
 #define memset_io memset_io
 
-#include <asm-generic/iomap.h>
-
 /*
  * ISA space is 'always mapped' on a typical x86 system, no need to
  * explicitly ioremap() it. The fact that the ISA IO space is mapped
@@ -329,6 +327,8 @@ extern bool is_early_ioremap_ptep(pte_t *ptep);
 #include <asm-generic/io.h>
 #undef PCI_IOBASE
 
+#include <asm-generic/iomap.h>
+
 #ifdef CONFIG_MTRR
 extern int __must_check arch_phys_wc_index(int handle);
 #define arch_phys_wc_index arch_phys_wc_index


***Building error after removing ARCH_HAS_IOREMAP_xx
***
In file included from ./include/linux/io.h:13,
                 from ./include/linux/irq.h:20,
                 from ./include/xen/events.h:6,
                 from arch/x86/entry/common.c:25:
./arch/x86/include/asm/io.h:321: warning: "ioremap_wc" redefined
  321 | #define ioremap_wc ioremap_wc
      | 
In file included from ./arch/x86/include/asm/io.h:212:
./include/asm-generic/iomap.h:97: note: this is the location of the previous definition
   97 | #define ioremap_wc ioremap
      | 
./arch/x86/include/asm/io.h:323: warning: "ioremap_wt" redefined
  323 | #define ioremap_wt ioremap_wt
      | 
./include/asm-generic/iomap.h:101: note: this is the location of the previous definition
  101 | #define ioremap_wt ioremap