linux-kernel - Re: [PATCH 1/1] edac x38: new MC driver module

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Date:	Tue, 25 Nov 2008 11:55:10 +0900
From:	Hitoshi Mitake <h.mitake@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Luck, Tony" <tony.luck@...el.com>,
	Russell King <rmk+lkml@....linux.org.uk>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Doug Thompson <norsk5@...oo.com>,
	"dougthompson@...ssion.com" <dougthompson@...ssion.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH 1/1] edac x38: new MC driver module

On Mon, 24 Nov 2008 10:02:40 -0800
"H. Peter Anvin" <hpa@...or.com> wrote:

Thanks for your reviews and advices, Peter and Tony.

> Luck, Tony wrote:
> >>       volatile u32 __iomem *__p = addr;
> >>       u32 __l, __h;
> > 
> > Do we really need all the "__" inside an inline function?  Why
> > not just call these "p", "l" and "h"?
> 
> Sorry, user space habit (in userspace, and in anything that can be
> included from userspace, one needs the __ to keep the namespace clean.)

I think which need __ is variable type name, not each variable name.
Name of each local variables can't effect namespace.
And I found this comment in asm-generic/int-ll64.h,
/*
 * __xx is ok: it doesn't pollute the POSIX namespace. Use these in the
 * header files exported to user space
 */

According to your advice, I rewrote the patch, how is this?

description of this patch: Adding config value to x86 architecture to determine existence of readq/writeq

Signed-off-by: Hitoshi Mitake <h.mitake@...il.com>
---
 arch/x86/Kconfig          |    3 +++
 arch/x86/include/asm/io.h |   17 +++++++++++++++++
 2 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ac22bb7..8f3c949 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -11,9 +11,12 @@ config 64BIT
 
 config X86_32
 	def_bool !64BIT
+	select ARCH_HAS_READQ
 
 config X86_64
 	def_bool 64BIT
+	select ARCH_HAS_READQ
+	select ARCH_HAS_WRITEQ
 
 ### Arch settings
 config X86
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index ac2abc8..5322d18 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -4,6 +4,7 @@
 #define ARCH_HAS_IOREMAP_WC
 
 #include <linux/compiler.h>
+#include <asm-generic/int-ll64.h>
 
 #define build_mmio_read(name, size, type, reg, barrier) \
 static inline type name(const volatile void __iomem *addr) \
@@ -57,6 +58,22 @@ build_mmio_write(__writeq, "q", unsigned long, "r", )
 /* Let people know we have them */
 #define readq readq
 #define writeq writeq
+
+#else  /* CONFIG_X86_32 from here */
+
+static inline __u64 readq(const volatile void __iomem *addr)
+{
+	const volatile u32 __iomem *p = addr;
+	u32 l, h;
+
+	l = readl(p);
+	h = readl(p+1);
+
+	return l + ((u64)h << 32);
+}
+
+#define readq readq
+
 #endif
 
 extern int iommu_bio_merge;
-- 
1.5.6.5

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