Re: [PATCH 1/2 v2, RFC] ACPI / memhotplug: Bind removable memory blocks to ACPI device nodes

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Hi Rafael,

Seems OK to me.

Reviewed-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>

Thanks. :)

On 05/04/2013 07:12 PM, Rafael J. Wysocki wrote:
From: Rafael J. Wysocki<rafael.j.wysocki@xxxxxxxxx>

During ACPI memory hotplug configuration bind memory blocks residing
in modules removable through the standard ACPI mechanism to struct
acpi_device objects associated with ACPI namespace objects
representing those modules.  Accordingly, unbind those memory blocks
from the struct acpi_device objects when the memory modules in
question are being removed.

When "offline" operation for devices representing memory blocks is
introduced, this will allow the ACPI core's device hot-remove code to
use it to carry out remove_memory() for those memory blocks and check
the results of that before it actually removes the modules holding
them from the system.

Since walk_memory_range() is used for accessing all memory blocks
corresponding to a given ACPI namespace object, it is exported from
memory_hotplug.c so that the code in acpi_memhotplug.c can use it.

Signed-off-by: Rafael J. Wysocki<rafael.j.wysocki@xxxxxxxxx>
---
  drivers/acpi/acpi_memhotplug.c |   53 ++++++++++++++++++++++++++++++++++++++---
  include/linux/memory_hotplug.h |    2 +
  mm/memory_hotplug.c            |    4 ++-
  3 files changed, 55 insertions(+), 4 deletions(-)

Index: linux-pm/mm/memory_hotplug.c
===================================================================
--- linux-pm.orig/mm/memory_hotplug.c
+++ linux-pm/mm/memory_hotplug.c
@@ -1618,6 +1618,7 @@ int offline_pages(unsigned long start_pf
  {
  	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
  }
+#endif /* CONFIG_MEMORY_HOTREMOVE */

  /**
   * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
@@ -1631,7 +1632,7 @@ int offline_pages(unsigned long start_pf
   *
   * Returns the return value of func.
   */
-static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
  		void *arg, int (*func)(struct memory_block *, void *))
  {
  	struct memory_block *mem = NULL;
@@ -1668,6 +1669,7 @@ static int walk_memory_range(unsigned lo
  	return 0;
  }

+#ifdef CONFIG_MEMORY_HOTREMOVE
  /**
   * offline_memory_block_cb - callback function for offlining memory block
   * @mem: the memory block to be offlined
Index: linux-pm/include/linux/memory_hotplug.h
===================================================================
--- linux-pm.orig/include/linux/memory_hotplug.h
+++ linux-pm/include/linux/memory_hotplug.h
@@ -245,6 +245,8 @@ static inline int is_mem_section_removab
  static inline void try_offline_node(int nid) {}
  #endif /* CONFIG_MEMORY_HOTREMOVE */

+extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+		void *arg, int (*func)(struct memory_block *, void *));
  extern int mem_online_node(int nid);
  extern int add_memory(int nid, u64 start, u64 size);
  extern int arch_add_memory(int nid, u64 start, u64 size);
Index: linux-pm/drivers/acpi/acpi_memhotplug.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpi_memhotplug.c
+++ linux-pm/drivers/acpi/acpi_memhotplug.c
@@ -28,6 +28,7 @@
   */

  #include<linux/acpi.h>
+#include<linux/memory.h>
  #include<linux/memory_hotplug.h>

  #include "internal.h"
@@ -166,13 +167,50 @@ static int acpi_memory_check_device(stru
  	return 0;
  }

+static unsigned long acpi_meminfo_start_pfn(struct acpi_memory_info *info)
+{
+	return PFN_DOWN(info->start_addr);
+}
+
+static unsigned long acpi_meminfo_end_pfn(struct acpi_memory_info *info)
+{
+	return PFN_UP(info->start_addr + info->length-1);
+}
+
+static int acpi_bind_memblk(struct memory_block *mem, void *arg)
+{
+	return acpi_bind_one(&mem->dev, (acpi_handle)arg);
+}
+
+static int acpi_bind_memory_blocks(struct acpi_memory_info *info,
+				   acpi_handle handle)
+{
+	return walk_memory_range(acpi_meminfo_start_pfn(info),
+				 acpi_meminfo_end_pfn(info), (void *)handle,
+				 acpi_bind_memblk);
+}
+
+static int acpi_unbind_memblk(struct memory_block *mem, void *arg)
+{
+	acpi_unbind_one(&mem->dev);
+	return 0;
+}
+
+static void acpi_unbind_memory_blocks(struct acpi_memory_info *info,
+				      acpi_handle handle)
+{
+	walk_memory_range(acpi_meminfo_start_pfn(info),
+			  acpi_meminfo_end_pfn(info), NULL, acpi_unbind_memblk);
+}
+
  static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
  {
+	acpi_handle handle = mem_device->device->handle;
  	int result, num_enabled = 0;
  	struct acpi_memory_info *info;
  	int node;

-	node = acpi_get_node(mem_device->device->handle);
+	node = acpi_get_node(handle);
  	/*
  	 * Tell the VM there is more memory here...
  	 * Note: Assume that this function returns zero on success
@@ -203,6 +241,12 @@ static int acpi_memory_enable_device(str
  		if (result&&  result != -EEXIST)
  			continue;

+		result = acpi_bind_memory_blocks(info, handle);
+		if (result) {
+			acpi_unbind_memory_blocks(info, handle);
+			return -ENODEV;
+		}
+
  		info->enabled = 1;

  		/*
@@ -229,10 +273,11 @@ static int acpi_memory_enable_device(str

  static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
  {
+	acpi_handle handle = mem_device->device->handle;
  	int result = 0, nid;
  	struct acpi_memory_info *info, *n;

-	nid = acpi_get_node(mem_device->device->handle);
+	nid = acpi_get_node(handle);

  	list_for_each_entry_safe(info, n,&mem_device->res_list, list) {
  		if (!info->enabled)
@@ -240,6 +285,8 @@ static int acpi_memory_remove_memory(str

  		if (nid<  0)
  			nid = memory_add_physaddr_to_nid(info->start_addr);
+
+		acpi_unbind_memory_blocks(info, handle);
  		result = remove_memory(nid, info->start_addr, info->length);
  		if (result)
  			return result;
@@ -300,7 +347,7 @@ static int acpi_memory_device_add(struct
  	if (result) {
  		dev_err(&device->dev, "acpi_memory_enable_device() error\n");
  		acpi_memory_device_free(mem_device);
-		return -ENODEV;
+		return result;
  	}

  	dev_dbg(&device->dev, "Memory device configured by ACPI\n");

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