[PATCH v2] ACPI: Add sysfs links from memory device to memblocks

Toshi Kani
2013-02-25T21:13:14Z

In order to eject a memory device object represented as "PNP0C80:%d"
in sysfs, its associated memblocks (system/memory/memory%d) need to
be off-lined. However, there is no user friendly way to correlate
between a memory device object and its memblocks in sysfs.

This patch creates sysfs links to memblocks under a memory device
object so that a user can easily checks and manipulates its memblocks
in sysfs.

For example, when PNP0C80:05 is associated with memory8 and memory9,
the following two links are created under PNP0C80:05. This allows
a user to access memory8/9 directly from PNP0C80:05.

# ll /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C80:05
lrwxrwxrwx. memory8 -> ../../../system/memory/memory8
lrwxrwxrwx. memory9 -> ../../../system/memory/memory9

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---

This patch applies on top of the Rafael's patch below.
https://patchwork.kernel.org/patch/2153261/

v2: Added a NULL return check for find_memory_block_hinted() as
pointed by Yasuaki Ishimatsu.

---
drivers/acpi/acpi_memhotplug.c | 56 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 3b3abbc..98477a5 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/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"
@@ -168,6 +169,55 @@ static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
return 0;
}

+static void acpi_setup_mem_blk_links(struct acpi_memory_device *mem_device,
+ struct acpi_memory_info *info, bool add_links)
+{
+ struct memory_block *mem_blk = NULL;
+ struct mem_section *mem_sect;
+ unsigned long start_pfn, end_pfn, pfn;
+ unsigned long section_nr;
+ int ret;
+
+ start_pfn = PFN_DOWN(info->start_addr);
+ end_pfn = PFN_UP(info->start_addr + info->length-1);
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ section_nr = pfn_to_section_nr(pfn);
+
+ if (!present_section_nr(section_nr))
+ continue;
+
+ mem_sect = __nr_to_section(section_nr);
+
+ /* skip if the same memblock */
+ if (mem_blk)
+ if ((section_nr >= mem_blk->start_section_nr) &&
+ (section_nr <= mem_blk->end_section_nr))
+ continue;
+
+ mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
+ if (!mem_blk)
+ continue;
+
+ if (add_links) {
+ ret = sysfs_create_link_nowarn(
+ &mem_device->device->dev.kobj,
+ &mem_blk->dev.kobj,
+ kobject_name(&mem_blk->dev.kobj));
+ if (ret && ret != -EEXIST)
+ dev_err(&mem_device->device->dev,
+ "Failed to create sysfs link %s\n",
+ kobject_name(&mem_blk->dev.kobj));
+ } else {
+ sysfs_remove_link(&mem_device->device->dev.kobj,
+ kobject_name(&mem_blk->dev.kobj));
+ }
+ }
+
+ if (mem_blk)
+ kobject_put(&mem_blk->dev.kobj);
+}
+
static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
{
int result, num_enabled = 0;
@@ -207,6 +257,9 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
continue;
}

+ /* Create sysfs links to its mem_blk devices */
+ acpi_setup_mem_blk_links(mem_device, info, true);
+
if (!result)
info->enabled = 1;
/*
@@ -241,6 +294,9 @@ static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
/* The kernel does not use this memory block */
continue;

+ /* Remove sysfs links to its mem_blk devices */
+ acpi_setup_mem_blk_links(mem_device, info, false);
+
if (!info->enabled)
/*
* The kernel uses this memory block, but it may be not