linux-stable/drivers/base/memory.c
David Hildenbrand e9a2e48e87 drivers/base/memory: don't store phys_device in memory blocks
No need to store the value for each and every memory block, as we can
easily query the value at runtime.  Reshuffle the members to optimize the
memory layout.  Also, let's clarify what the interface once was used for
and why it's legacy nowadays.

"phys_device" was used on s390x in older versions of lsmem[2]/chmem[3],
back when they were still part of s390x-tools.  They were later replaced
by the variants in linux-utils.  For example, RHEL6 and RHEL7 contain
lsmem/chmem from s390-utils.  RHEL8 switched to versions from util-linux
on s390x [4].

"phys_device" was added with sysfs support for memory hotplug in commit
3947be1969 ("[PATCH] memory hotplug: sysfs and add/remove functions") in
2005.  It always returned 0.

s390x started returning something != 0 on some setups (if sclp.rzm is set
by HW) in 2010 via commit 57b552ba0b ("memory hotplug/s390: set
phys_device").

For s390x, it allowed for identifying which memory block devices belong to
the same storage increment (RZM).  Only if all memory block devices
comprising a single storage increment were offline, the memory could
actually be removed in the hypervisor.

Since commit e5d709bb5f ("s390/memory hotplug: provide
memory_block_size_bytes() function") in 2013 a memory block device spans
at least one storage increment - which is why the interface isn't really
helpful/used anymore (except by old lsmem/chmem tools).

There were once RFC patches to make use of "phys_device" in ACPI context;
however, the underlying problem could be solved using different interfaces
[1].

[1] https://patchwork.kernel.org/patch/2163871/
[2] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/lsmem
[3] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/chmem
[4] https://bugzilla.redhat.com/show_bug.cgi?id=1504134

Link: https://lkml.kernel.org/r/20210201181347.13262-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-26 09:41:00 -08:00

824 lines
20 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Memory subsystem support
*
* Written by Matt Tolentino <matthew.e.tolentino@intel.com>
* Dave Hansen <haveblue@us.ibm.com>
*
* This file provides the necessary infrastructure to represent
* a SPARSEMEM-memory-model system's physical memory in /sysfs.
* All arch-independent code that assumes MEMORY_HOTPLUG requires
* SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/topology.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/xarray.h>
#include <linux/atomic.h>
#include <linux/uaccess.h>
#define MEMORY_CLASS_NAME "memory"
static const char *const online_type_to_str[] = {
[MMOP_OFFLINE] = "offline",
[MMOP_ONLINE] = "online",
[MMOP_ONLINE_KERNEL] = "online_kernel",
[MMOP_ONLINE_MOVABLE] = "online_movable",
};
int mhp_online_type_from_str(const char *str)
{
int i;
for (i = 0; i < ARRAY_SIZE(online_type_to_str); i++) {
if (sysfs_streq(str, online_type_to_str[i]))
return i;
}
return -EINVAL;
}
#define to_memory_block(dev) container_of(dev, struct memory_block, dev)
static int sections_per_block;
static inline unsigned long memory_block_id(unsigned long section_nr)
{
return section_nr / sections_per_block;
}
static inline unsigned long pfn_to_block_id(unsigned long pfn)
{
return memory_block_id(pfn_to_section_nr(pfn));
}
static inline unsigned long phys_to_block_id(unsigned long phys)
{
return pfn_to_block_id(PFN_DOWN(phys));
}
static int memory_subsys_online(struct device *dev);
static int memory_subsys_offline(struct device *dev);
static struct bus_type memory_subsys = {
.name = MEMORY_CLASS_NAME,
.dev_name = MEMORY_CLASS_NAME,
.online = memory_subsys_online,
.offline = memory_subsys_offline,
};
/*
* Memory blocks are cached in a local radix tree to avoid
* a costly linear search for the corresponding device on
* the subsystem bus.
*/
static DEFINE_XARRAY(memory_blocks);
static BLOCKING_NOTIFIER_HEAD(memory_chain);
int register_memory_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&memory_chain, nb);
}
EXPORT_SYMBOL(register_memory_notifier);
void unregister_memory_notifier(struct notifier_block *nb)
{
blocking_notifier_chain_unregister(&memory_chain, nb);
}
EXPORT_SYMBOL(unregister_memory_notifier);
static void memory_block_release(struct device *dev)
{
struct memory_block *mem = to_memory_block(dev);
kfree(mem);
}
unsigned long __weak memory_block_size_bytes(void)
{
return MIN_MEMORY_BLOCK_SIZE;
}
EXPORT_SYMBOL_GPL(memory_block_size_bytes);
/*
* Show the first physical section index (number) of this memory block.
*/
static ssize_t phys_index_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem = to_memory_block(dev);
unsigned long phys_index;
phys_index = mem->start_section_nr / sections_per_block;
return sysfs_emit(buf, "%08lx\n", phys_index);
}
/*
* Legacy interface that we cannot remove. Always indicate "removable"
* with CONFIG_MEMORY_HOTREMOVE - bad heuristic.
*/
static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
return sysfs_emit(buf, "%d\n", (int)IS_ENABLED(CONFIG_MEMORY_HOTREMOVE));
}
/*
* online, offline, going offline, etc.
*/
static ssize_t state_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct memory_block *mem = to_memory_block(dev);
const char *output;
/*
* We can probably put these states in a nice little array
* so that they're not open-coded
*/
switch (mem->state) {
case MEM_ONLINE:
output = "online";
break;
case MEM_OFFLINE:
output = "offline";
break;
case MEM_GOING_OFFLINE:
output = "going-offline";
break;
default:
WARN_ON(1);
return sysfs_emit(buf, "ERROR-UNKNOWN-%ld\n", mem->state);
}
return sysfs_emit(buf, "%s\n", output);
}
int memory_notify(unsigned long val, void *v)
{
return blocking_notifier_call_chain(&memory_chain, val, v);
}
/*
* MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
* OK to have direct references to sparsemem variables in here.
*/
static int
memory_block_action(unsigned long start_section_nr, unsigned long action,
int online_type, int nid)
{
unsigned long start_pfn;
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
int ret;
start_pfn = section_nr_to_pfn(start_section_nr);
switch (action) {
case MEM_ONLINE:
ret = online_pages(start_pfn, nr_pages, online_type, nid);
break;
case MEM_OFFLINE:
ret = offline_pages(start_pfn, nr_pages);
break;
default:
WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
"%ld\n", __func__, start_section_nr, action, action);
ret = -EINVAL;
}
return ret;
}
static int memory_block_change_state(struct memory_block *mem,
unsigned long to_state, unsigned long from_state_req)
{
int ret = 0;
if (mem->state != from_state_req)
return -EINVAL;
if (to_state == MEM_OFFLINE)
mem->state = MEM_GOING_OFFLINE;
ret = memory_block_action(mem->start_section_nr, to_state,
mem->online_type, mem->nid);
mem->state = ret ? from_state_req : to_state;
return ret;
}
/* The device lock serializes operations on memory_subsys_[online|offline] */
static int memory_subsys_online(struct device *dev)
{
struct memory_block *mem = to_memory_block(dev);
int ret;
if (mem->state == MEM_ONLINE)
return 0;
/*
* When called via device_online() without configuring the online_type,
* we want to default to MMOP_ONLINE.
*/
if (mem->online_type == MMOP_OFFLINE)
mem->online_type = MMOP_ONLINE;
ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
mem->online_type = MMOP_OFFLINE;
return ret;
}
static int memory_subsys_offline(struct device *dev)
{
struct memory_block *mem = to_memory_block(dev);
if (mem->state == MEM_OFFLINE)
return 0;
return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
}
static ssize_t state_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
const int online_type = mhp_online_type_from_str(buf);
struct memory_block *mem = to_memory_block(dev);
int ret;
if (online_type < 0)
return -EINVAL;
ret = lock_device_hotplug_sysfs();
if (ret)
return ret;
switch (online_type) {
case MMOP_ONLINE_KERNEL:
case MMOP_ONLINE_MOVABLE:
case MMOP_ONLINE:
/* mem->online_type is protected by device_hotplug_lock */
mem->online_type = online_type;
ret = device_online(&mem->dev);
break;
case MMOP_OFFLINE:
ret = device_offline(&mem->dev);
break;
default:
ret = -EINVAL; /* should never happen */
}
unlock_device_hotplug();
if (ret < 0)
return ret;
if (ret)
return -EINVAL;
return count;
}
/*
* Legacy interface that we cannot remove: s390x exposes the storage increment
* covered by a memory block, allowing for identifying which memory blocks
* comprise a storage increment. Since a memory block spans complete
* storage increments nowadays, this interface is basically unused. Other
* archs never exposed != 0.
*/
static ssize_t phys_device_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem = to_memory_block(dev);
unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
return sysfs_emit(buf, "%d\n",
arch_get_memory_phys_device(start_pfn));
}
#ifdef CONFIG_MEMORY_HOTREMOVE
static int print_allowed_zone(char *buf, int len, int nid,
unsigned long start_pfn, unsigned long nr_pages,
int online_type, struct zone *default_zone)
{
struct zone *zone;
zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
if (zone == default_zone)
return 0;
return sysfs_emit_at(buf, len, " %s", zone->name);
}
static ssize_t valid_zones_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem = to_memory_block(dev);
unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
struct zone *default_zone;
int len = 0;
int nid;
/*
* Check the existing zone. Make sure that we do that only on the
* online nodes otherwise the page_zone is not reliable
*/
if (mem->state == MEM_ONLINE) {
/*
* The block contains more than one zone can not be offlined.
* This can happen e.g. for ZONE_DMA and ZONE_DMA32
*/
default_zone = test_pages_in_a_zone(start_pfn,
start_pfn + nr_pages);
if (!default_zone)
return sysfs_emit(buf, "%s\n", "none");
len += sysfs_emit_at(buf, len, "%s", default_zone->name);
goto out;
}
nid = mem->nid;
default_zone = zone_for_pfn_range(MMOP_ONLINE, nid, start_pfn,
nr_pages);
len += sysfs_emit_at(buf, len, "%s", default_zone->name);
len += print_allowed_zone(buf, len, nid, start_pfn, nr_pages,
MMOP_ONLINE_KERNEL, default_zone);
len += print_allowed_zone(buf, len, nid, start_pfn, nr_pages,
MMOP_ONLINE_MOVABLE, default_zone);
out:
len += sysfs_emit_at(buf, len, "\n");
return len;
}
static DEVICE_ATTR_RO(valid_zones);
#endif
static DEVICE_ATTR_RO(phys_index);
static DEVICE_ATTR_RW(state);
static DEVICE_ATTR_RO(phys_device);
static DEVICE_ATTR_RO(removable);
/*
* Show the memory block size (shared by all memory blocks).
*/
static ssize_t block_size_bytes_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sysfs_emit(buf, "%lx\n", memory_block_size_bytes());
}
static DEVICE_ATTR_RO(block_size_bytes);
/*
* Memory auto online policy.
*/
static ssize_t auto_online_blocks_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sysfs_emit(buf, "%s\n",
online_type_to_str[mhp_default_online_type]);
}
static ssize_t auto_online_blocks_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
const int online_type = mhp_online_type_from_str(buf);
if (online_type < 0)
return -EINVAL;
mhp_default_online_type = online_type;
return count;
}
static DEVICE_ATTR_RW(auto_online_blocks);
/*
* Some architectures will have custom drivers to do this, and
* will not need to do it from userspace. The fake hot-add code
* as well as ppc64 will do all of their discovery in userspace
* and will require this interface.
*/
#ifdef CONFIG_ARCH_MEMORY_PROBE
static ssize_t probe_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
u64 phys_addr;
int nid, ret;
unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
ret = kstrtoull(buf, 0, &phys_addr);
if (ret)
return ret;
if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
return -EINVAL;
ret = lock_device_hotplug_sysfs();
if (ret)
return ret;
nid = memory_add_physaddr_to_nid(phys_addr);
ret = __add_memory(nid, phys_addr,
MIN_MEMORY_BLOCK_SIZE * sections_per_block,
MHP_NONE);
if (ret)
goto out;
ret = count;
out:
unlock_device_hotplug();
return ret;
}
static DEVICE_ATTR_WO(probe);
#endif
#ifdef CONFIG_MEMORY_FAILURE
/*
* Support for offlining pages of memory
*/
/* Soft offline a page */
static ssize_t soft_offline_page_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int ret;
u64 pfn;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (kstrtoull(buf, 0, &pfn) < 0)
return -EINVAL;
pfn >>= PAGE_SHIFT;
ret = soft_offline_page(pfn, 0);
return ret == 0 ? count : ret;
}
/* Forcibly offline a page, including killing processes. */
static ssize_t hard_offline_page_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int ret;
u64 pfn;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (kstrtoull(buf, 0, &pfn) < 0)
return -EINVAL;
pfn >>= PAGE_SHIFT;
ret = memory_failure(pfn, 0);
return ret ? ret : count;
}
static DEVICE_ATTR_WO(soft_offline_page);
static DEVICE_ATTR_WO(hard_offline_page);
#endif
/* See phys_device_show(). */
int __weak arch_get_memory_phys_device(unsigned long start_pfn)
{
return 0;
}
/*
* A reference for the returned memory block device is acquired.
*
* Called under device_hotplug_lock.
*/
static struct memory_block *find_memory_block_by_id(unsigned long block_id)
{
struct memory_block *mem;
mem = xa_load(&memory_blocks, block_id);
if (mem)
get_device(&mem->dev);
return mem;
}
/*
* Called under device_hotplug_lock.
*/
struct memory_block *find_memory_block(struct mem_section *section)
{
unsigned long block_id = memory_block_id(__section_nr(section));
return find_memory_block_by_id(block_id);
}
static struct attribute *memory_memblk_attrs[] = {
&dev_attr_phys_index.attr,
&dev_attr_state.attr,
&dev_attr_phys_device.attr,
&dev_attr_removable.attr,
#ifdef CONFIG_MEMORY_HOTREMOVE
&dev_attr_valid_zones.attr,
#endif
NULL
};
static struct attribute_group memory_memblk_attr_group = {
.attrs = memory_memblk_attrs,
};
static const struct attribute_group *memory_memblk_attr_groups[] = {
&memory_memblk_attr_group,
NULL,
};
/*
* register_memory - Setup a sysfs device for a memory block
*/
static
int register_memory(struct memory_block *memory)
{
int ret;
memory->dev.bus = &memory_subsys;
memory->dev.id = memory->start_section_nr / sections_per_block;
memory->dev.release = memory_block_release;
memory->dev.groups = memory_memblk_attr_groups;
memory->dev.offline = memory->state == MEM_OFFLINE;
ret = device_register(&memory->dev);
if (ret) {
put_device(&memory->dev);
return ret;
}
ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory,
GFP_KERNEL));
if (ret) {
put_device(&memory->dev);
device_unregister(&memory->dev);
}
return ret;
}
static int init_memory_block(unsigned long block_id, unsigned long state)
{
struct memory_block *mem;
int ret = 0;
mem = find_memory_block_by_id(block_id);
if (mem) {
put_device(&mem->dev);
return -EEXIST;
}
mem = kzalloc(sizeof(*mem), GFP_KERNEL);
if (!mem)
return -ENOMEM;
mem->start_section_nr = block_id * sections_per_block;
mem->state = state;
mem->nid = NUMA_NO_NODE;
ret = register_memory(mem);
return ret;
}
static int add_memory_block(unsigned long base_section_nr)
{
int section_count = 0;
unsigned long nr;
for (nr = base_section_nr; nr < base_section_nr + sections_per_block;
nr++)
if (present_section_nr(nr))
section_count++;
if (section_count == 0)
return 0;
return init_memory_block(memory_block_id(base_section_nr),
MEM_ONLINE);
}
static void unregister_memory(struct memory_block *memory)
{
if (WARN_ON_ONCE(memory->dev.bus != &memory_subsys))
return;
WARN_ON(xa_erase(&memory_blocks, memory->dev.id) == NULL);
/* drop the ref. we got via find_memory_block() */
put_device(&memory->dev);
device_unregister(&memory->dev);
}
/*
* Create memory block devices for the given memory area. Start and size
* have to be aligned to memory block granularity. Memory block devices
* will be initialized as offline.
*
* Called under device_hotplug_lock.
*/
int create_memory_block_devices(unsigned long start, unsigned long size)
{
const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
struct memory_block *mem;
unsigned long block_id;
int ret = 0;
if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
!IS_ALIGNED(size, memory_block_size_bytes())))
return -EINVAL;
for (block_id = start_block_id; block_id != end_block_id; block_id++) {
ret = init_memory_block(block_id, MEM_OFFLINE);
if (ret)
break;
}
if (ret) {
end_block_id = block_id;
for (block_id = start_block_id; block_id != end_block_id;
block_id++) {
mem = find_memory_block_by_id(block_id);
if (WARN_ON_ONCE(!mem))
continue;
unregister_memory(mem);
}
}
return ret;
}
/*
* Remove memory block devices for the given memory area. Start and size
* have to be aligned to memory block granularity. Memory block devices
* have to be offline.
*
* Called under device_hotplug_lock.
*/
void remove_memory_block_devices(unsigned long start, unsigned long size)
{
const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
const unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
struct memory_block *mem;
unsigned long block_id;
if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
!IS_ALIGNED(size, memory_block_size_bytes())))
return;
for (block_id = start_block_id; block_id != end_block_id; block_id++) {
mem = find_memory_block_by_id(block_id);
if (WARN_ON_ONCE(!mem))
continue;
unregister_memory_block_under_nodes(mem);
unregister_memory(mem);
}
}
/* return true if the memory block is offlined, otherwise, return false */
bool is_memblock_offlined(struct memory_block *mem)
{
return mem->state == MEM_OFFLINE;
}
static struct attribute *memory_root_attrs[] = {
#ifdef CONFIG_ARCH_MEMORY_PROBE
&dev_attr_probe.attr,
#endif
#ifdef CONFIG_MEMORY_FAILURE
&dev_attr_soft_offline_page.attr,
&dev_attr_hard_offline_page.attr,
#endif
&dev_attr_block_size_bytes.attr,
&dev_attr_auto_online_blocks.attr,
NULL
};
static struct attribute_group memory_root_attr_group = {
.attrs = memory_root_attrs,
};
static const struct attribute_group *memory_root_attr_groups[] = {
&memory_root_attr_group,
NULL,
};
/*
* Initialize the sysfs support for memory devices. At the time this function
* is called, we cannot have concurrent creation/deletion of memory block
* devices, the device_hotplug_lock is not needed.
*/
void __init memory_dev_init(void)
{
int ret;
unsigned long block_sz, nr;
/* Validate the configured memory block size */
block_sz = memory_block_size_bytes();
if (!is_power_of_2(block_sz) || block_sz < MIN_MEMORY_BLOCK_SIZE)
panic("Memory block size not suitable: 0x%lx\n", block_sz);
sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
if (ret)
panic("%s() failed to register subsystem: %d\n", __func__, ret);
/*
* Create entries for memory sections that were found
* during boot and have been initialized
*/
for (nr = 0; nr <= __highest_present_section_nr;
nr += sections_per_block) {
ret = add_memory_block(nr);
if (ret)
panic("%s() failed to add memory block: %d\n", __func__,
ret);
}
}
/**
* walk_memory_blocks - walk through all present memory blocks overlapped
* by the range [start, start + size)
*
* @start: start address of the memory range
* @size: size of the memory range
* @arg: argument passed to func
* @func: callback for each memory section walked
*
* This function walks through all present memory blocks overlapped by the
* range [start, start + size), calling func on each memory block.
*
* In case func() returns an error, walking is aborted and the error is
* returned.
*
* Called under device_hotplug_lock.
*/
int walk_memory_blocks(unsigned long start, unsigned long size,
void *arg, walk_memory_blocks_func_t func)
{
const unsigned long start_block_id = phys_to_block_id(start);
const unsigned long end_block_id = phys_to_block_id(start + size - 1);
struct memory_block *mem;
unsigned long block_id;
int ret = 0;
if (!size)
return 0;
for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
mem = find_memory_block_by_id(block_id);
if (!mem)
continue;
ret = func(mem, arg);
put_device(&mem->dev);
if (ret)
break;
}
return ret;
}
struct for_each_memory_block_cb_data {
walk_memory_blocks_func_t func;
void *arg;
};
static int for_each_memory_block_cb(struct device *dev, void *data)
{
struct memory_block *mem = to_memory_block(dev);
struct for_each_memory_block_cb_data *cb_data = data;
return cb_data->func(mem, cb_data->arg);
}
/**
* for_each_memory_block - walk through all present memory blocks
*
* @arg: argument passed to func
* @func: callback for each memory block walked
*
* This function walks through all present memory blocks, calling func on
* each memory block.
*
* In case func() returns an error, walking is aborted and the error is
* returned.
*/
int for_each_memory_block(void *arg, walk_memory_blocks_func_t func)
{
struct for_each_memory_block_cb_data cb_data = {
.func = func,
.arg = arg,
};
return bus_for_each_dev(&memory_subsys, NULL, &cb_data,
for_each_memory_block_cb);
}