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    SubjectRe: [PATCH 4/4] kcore: remove noise from walk_memory_resource
    On Wed, 22 Jul 2009 14:21:03 +0800
    Amerigo Wang <xiyou.wangcong@gmail.com> wrote:

    > On Wed, Jul 22, 2009 at 02:12:27PM +0900, KAMEZAWA Hiroyuki wrote:
    > >From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.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@jp.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() ?


    > >+ */
    > > int
    > > walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
    > >- int (*func)(unsigned long, unsigned long, void *))
    > >+ int (*func)(unsigned long, unsigned long, void *))
    >
    >
    > This line is a trivial change, I don't want to see it mixed with
    > the rest...
    Sorry, this was from a trial I tried to change the name ;) I'll remove this.

    I'll post v3 but wait for a day to hear other comments.

    Thank you for review.

    Regards,
    -Kame

    >
    >
    > > {
    > > struct resource res;
    > > unsigned long pfn, len;
    > > u64 orig_end;
    > > int ret = -1;
    > >+
    > > res.start = (u64) start_pfn << PAGE_SHIFT;
    > > res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
    > > res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
    > > orig_end = res.end;
    > >- while ((res.start < res.end) && (find_next_system_ram(&res) >= 0)) {
    > >+ while ((res.start < res.end) &&
    > >+ (find_next_system_ram(&res, "System RAM") >= 0)) {
    > > pfn = (unsigned long)(res.start >> PAGE_SHIFT);
    > > len = (unsigned long)((res.end + 1 - res.start) >> PAGE_SHIFT);
    > > ret = (*func)(pfn, len, arg);
    > >
    > >--
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    >



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