[PATCH 3/3] Add arch-specific walk_memory_remove() for ppc64

[Badari Pulavarty]

walk_memory_resource() verifies if there are holes in a given
memory range, by checking against /proc/iomem. On x86/ia64
system memory is represented in /proc/iomem. On PPC64, we
don't show system memory as IO resource in /proc/iomem - instead
its maintained in /proc/device-tree. 

This patch provides a way for an architecture to provide its
own walk_memory_resource() function. On PPC64, the memory
region is small (16MB), contiguous and non-overlapping.
So extra checking, against device-tree is not needed.

Signed-off-by: Badari Pulavarty <pbadari at us.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
---
 arch/powerpc/Kconfig  |    3 +++
 arch/powerpc/mm/mem.c |   16 ++++++++++++++++
 kernel/resource.c     |    2 +-
 3 files changed, 20 insertions(+), 1 deletion(-)

Index: linux-2.6.24-rc1/arch/powerpc/mm/mem.c
===================================================================
--- linux-2.6.24-rc1.orig/arch/powerpc/mm/mem.c	2007-10-30 07:39:16.000000000 -0800
+++ linux-2.6.24-rc1/arch/powerpc/mm/mem.c	2007-10-31 07:17:52.000000000 -0800
@@ -129,6 +129,22 @@ int __devinit arch_add_memory(int nid, u
 	return __add_pages(zone, start_pfn, nr_pages);
 }
 
+/*
+ * walk_memory_resource() needs to make sure there is no holes in a given
+ * memory range. On PPC64, since this range comes from /sysfs, the range
+ * is guaranteed to be valid, non-overlapping and can not contain any
+ * holes. By the time we get here (memory add or remove), /proc/device-tree
+ * is updated and correct. Only reason we need to check against device-tree
+ * would be if we allow user-land to specify a memory range through a
+ * system call/ioctl etc.. (instead of doing offline/online through /sysfs.
+ */
+int
+walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
+			int (*func)(unsigned long, unsigned long, void *))
+{
+	return  (*func)(start_pfn, nr_pages, arg);
+}
+
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
Index: linux-2.6.24-rc1/kernel/resource.c
===================================================================
--- linux-2.6.24-rc1.orig/kernel/resource.c	2007-10-23 20:50:57.000000000 -0700
+++ linux-2.6.24-rc1/kernel/resource.c	2007-10-30 08:58:41.000000000 -0800
@@ -228,7 +228,7 @@ int release_resource(struct resource *ol
 
 EXPORT_SYMBOL(release_resource);
 
-#ifdef CONFIG_MEMORY_HOTPLUG
+#if defined(CONFIG_MEMORY_HOTPLUG) && !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.
Index: linux-2.6.24-rc1/arch/powerpc/Kconfig
===================================================================
--- linux-2.6.24-rc1.orig/arch/powerpc/Kconfig	2007-10-30 07:39:17.000000000 -0800
+++ linux-2.6.24-rc1/arch/powerpc/Kconfig	2007-10-30 08:54:57.000000000 -0800
@@ -234,6 +234,9 @@ config HOTPLUG_CPU
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
 
+config ARCH_HAS_WALK_MEMORY
+	def_bool y
+
 config ARCH_ENABLE_MEMORY_HOTREMOVE
 	def_bool y