linux-kernel - Re: [PATCH 4/4] kcore: remove noise from walk_memory

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Message-ID: <20090722062943.GF6281@cr0.nay.redhat.com>
Date:	Wed, 22 Jul 2009 14:29:43 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Amerigo Wang <xiyou.wangcong@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH 4/4] kcore: remove noise from walk_memory_resource

On Wed, Jul 22, 2009 at 03:22:38PM +0900, KAMEZAWA Hiroyuki wrote:
>On Wed, 22 Jul 2009 14:21:03 +0800
>Amerigo Wang <xiyou.wangcong@...il.com> wrote:
>
>> On Wed, Jul 22, 2009 at 02:12:27PM +0900, KAMEZAWA Hiroyuki wrote:
>> >From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>> >
>> >Originally, walk_memory_resource() was introduced to traverse all memory
>> >of "System RAM" for detecting memory hotplug/unplug range.
>> >For doing so, flags of IORESOUCE_MEM|IORESOURCE_BUSY was used and this
>> >was enough for memory hotplug because scanning range was controlled properly.
>> >
>> >But for using other purpose, /proc/kcore, this may includes some firmware
>> >area marked as IORESOURCE_BUSY | IORESOUCE_MEM. This patch makes the check
>> >strict to find out busy "System RAM".
>> >
>> >Note: PPC64 keeps their own walk_memory_resouce(), which walk through
>> >ppc64's lmb informaton. Because old kclist_add() is called per lmb,
>> >this patch makes no difference in behavior, finally.
>> >
>> >Changelog v2:
>> > - new patch from v2.
>> >
>> >Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>> >---
>> > kernel/resource.c |   18 ++++++++++++++----
>> > 1 file changed, 14 insertions(+), 4 deletions(-)
>> >
>> >Index: mmotm-2.6.31-Jul16/kernel/resource.c
>> >===================================================================
>> >--- mmotm-2.6.31-Jul16.orig/kernel/resource.c
>> >+++ mmotm-2.6.31-Jul16/kernel/resource.c
>> >@@ -237,10 +237,10 @@ EXPORT_SYMBOL(release_resource);
>> > #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
>> > /*
>> >  * Finds the lowest memory reosurce exists within [res->start.res->end)
>> >- * the caller must specify res->start, res->end, res->flags.
>> >+ * the caller must specify res->start, res->end, res->flags and "name".
>> >  * If found, returns 0, res is overwritten, if not found, returns -1.
>> >  */
>> >-static int find_next_system_ram(struct resource *res)
>> >+static int find_next_system_ram(struct resource *res, char *name)
>> > {
>> > 	resource_size_t start, end;
>> > 	struct resource *p;
>> >@@ -256,6 +256,8 @@ static int find_next_system_ram(struct r
>> > 		/* system ram is just marked as IORESOURCE_MEM */
>> > 		if (p->flags != res->flags)
>> > 			continue;
>> >+		if (name && strcmp(p->name, name))
>> >+			continue;
>> > 		if (p->start > end) {
>> > 			p = NULL;
>> > 			break;
>> >@@ -273,19 +275,27 @@ static int find_next_system_ram(struct r
>> > 		res->end = p->end;
>> > 	return 0;
>> > }
>> >+
>> >+/*
>> >+ * This function calls callback against all memory range of "System RAM"
>> >+ * which are marked as IORESOURCE_MEM and IORESOUCE_BUSY.
>> >+ * Now, this function is only for "System RAM".
>> 
>> 
>> Then we should change its name, shouldn't we? :)
>> 
>I tried, but not changed in this version bacause the usage/purpose is not changed.
>
>Hmm, How about walk_system_ram_range() ?


Fine for me.

Thank you.
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