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Date: Fri, 22 Jan 2010 16:16:19 +0800 From: Wu Fengguang <fengguang.wu@...el.com> To: "H. Peter Anvin" <hpa@...or.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, 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: [PATCH 1/3 v4] resources: introduce generic page_is_ram() On Fri, Jan 22, 2010 at 12:51:32AM -0700, H. Peter Anvin wrote: > On 01/21/2010 07:21 PM, Wu Fengguang wrote: > > --- linux-mm.orig/kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 > > +++ linux-mm/kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 > > @@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long > > > > #endif > > > > +#define PAGE_IS_RAM 24 > > +static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg) > > +{ > > + return PAGE_IS_RAM; > > +} > > +int __attribute__((weak)) page_is_ram(unsigned long pfn) > > +{ > > + return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram); > > +} > > +#undef PAGE_IS_RAM > > + > > Stylistic nitpick: > > The use of the magic number "24" here is pretty ugly; it seems to imply > that there is something peculiar with this number and that it is trying > to avoid an overlap, whereas in fact any number but 0 and -1 would do. Yes, exactly. > I would rather see just returning 1 and do: > > return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1; > > (walk_system_ram_range() returning -1 on error, and 0 means continue.) Good suggestion. > Note also that we don't write "constant == expression"; although some > schools teach it as a way to avoid the "=" versus "==" beginner C > mistake, it makes the code less intuitive to read. Yeah. > Other than that, the patchset looks good; if Ingo doesn't beat me to it > I'll put it in tomorrow (need sleep right now.) OK, thanks! Here is the updated patch. --- resources: introduce generic page_is_ram() It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram(). The static verions in MIPS and SCORE are also made global. v4: prefer plain 1 instead of PAGE_IS_RAM (H. Peter Anvin) v3: add comment (KAMEZAWA Hiroyuki) "AFAIK, this "System RAM" information has been used for kdump to grab valid memory area and seems good for the kernel itself." v2: add PAGE_IS_RAM macro (Américo Wang) CC: Chen Liqin <liqin.chen@...plusct.com> CC: Lennox Wu <lennox.wu@...il.com> CC: Ralf Baechle <ralf@...ux-mips.org> CC: Américo Wang <xiyou.wangcong@...il.com> CC: linux-mips@...ux-mips.org CC: Yinghai Lu <yinghai@...nel.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Signed-off-by: Wu Fengguang <fengguang.wu@...el.com> --- arch/mips/mm/init.c | 2 +- arch/score/mm/init.c | 2 +- include/linux/ioport.h | 2 ++ kernel/resource.c | 13 +++++++++++++ 4 files changed, 17 insertions(+), 2 deletions(-) --- linux-mm.orig/kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +++ linux-mm/kernel/resource.c 2010-01-22 16:12:55.000000000 +0800 @@ -327,6 +327,19 @@ int walk_system_ram_range(unsigned long #endif +static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg) +{ + return 1; +} +/* + * This generic page_is_ram() returns true if specified address is + * registered as "System RAM" in iomem_resource list. + */ +int __attribute__((weak)) page_is_ram(unsigned long pfn) +{ + return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1; +} + /* * 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); + #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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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