linux-kernel - Re: [PATCH 1/3 v4] resources: introduce generic page_is

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Date:	Wed, 27 Jan 2010 11:06:39 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Chen Liqin <liqin.chen@...plusct.com>,
	Lennox Wu <lennox.wu@...il.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Américo Wang <xiyou.wangcong@...il.com>,
	"linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Yinghai Lu <yinghai@...nel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	"Zheng, Shaohui" <shaohui.zheng@...el.com>
Subject: Re: [PATCH 1/3 v4] resources: introduce generic page_is_ram()

On Tue, Jan 26, 2010 at 05:30:58PM -0700, Andrew Morton wrote:

> > +int __attribute__((weak)) page_is_ram(unsigned long pfn)
> > +{
> > +	return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
> > +}
> 
> I'll switch this to use __weak.

Thanks.

> >  /*
> >   * Find empty slot in the resource tree given range and alignment.
> >   */
> > --- linux-mm.orig/include/linux/ioport.h	2010-01-22 11:20:34.000000000 +0800
> > +++ linux-mm/include/linux/ioport.h	2010-01-22 11:20:35.000000000 +0800
> > @@ -191,5 +191,7 @@ extern int
> >  walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
> >  		void *arg, int (*func)(unsigned long, unsigned long, void *));
> >  
> > +extern int page_is_ram(unsigned long pfn);
> 
> Is it appropriate that this function be declared in ioport.h?  It's a
> pretty general function.  Dunno.

Good suggestion. The following patch moves it to mm.h.

> >  #endif /* __ASSEMBLY__ */
> >  #endif	/* _LINUX_IOPORT_H */
> > --- linux-mm.orig/arch/score/mm/init.c	2010-01-22 11:20:34.000000000 +0800
> > +++ linux-mm/arch/score/mm/init.c	2010-01-22 11:20:35.000000000 +0800
> > @@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
> >  }
> >  
> >  #ifndef CONFIG_NEED_MULTIPLE_NODES
> > -static int __init page_is_ram(unsigned long pagenr)
> > +int page_is_ram(unsigned long pagenr)
> >  {
> >  	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
> >  		return 1;
> > --- linux-mm.orig/arch/mips/mm/init.c	2010-01-22 11:20:34.000000000 +0800
> > +++ linux-mm/arch/mips/mm/init.c	2010-01-22 11:20:35.000000000 +0800
> > @@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
> >  }
> >  
> >  #ifndef CONFIG_NEED_MULTIPLE_NODES
> > -static int __init page_is_ram(unsigned long pagenr)
> > +int page_is_ram(unsigned long pagenr)
> >  {
> >  	int i;
> 
> hm, so we lose the __init.

Maybe Ralf Baechle knows whether MIPS can switch to the (smaller) 
generic page_is_ram().

Thanks,
Fengguang
---
move page_is_ram() declaration to mm.h

---
 include/linux/ioport.h |    2 --
 include/linux/mm.h     |    2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

--- linux-mm.orig/include/linux/ioport.h	2010-01-27 11:04:22.000000000 +0800
+++ linux-mm/include/linux/ioport.h	2010-01-27 11:04:38.000000000 +0800
@@ -191,7 +191,5 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
-extern int page_is_ram(unsigned long pfn);
-
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */
--- linux-mm.orig/include/linux/mm.h	2010-01-27 11:04:43.000000000 +0800
+++ linux-mm/include/linux/mm.h	2010-01-27 11:05:30.000000000 +0800
@@ -265,6 +265,8 @@ static inline int get_page_unless_zero(s
 	return atomic_inc_not_zero(&page->_count);
 }
 
+extern int page_is_ram(unsigned long pfn);
+
 /* Support for virtually mapped pages */
 struct page *vmalloc_to_page(const void *addr);
 unsigned long vmalloc_to_pfn(const void *addr);

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