// SPDX-License-Identifier: GPL-2.0
/*
 * Basic Node interface support
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/memory.h>
#include <linux/mempolicy.h>
#include <linux/vmstat.h>
#include <linux/notifier.h>
#include <linux/node.h>
#include <linux/hugetlb.h>
#include <linux/compaction.h>
#include <linux/cpumask.h>
#include <linux/topology.h>
#include <linux/nodemask.h>
#include <linux/cpu.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/memblock.h>

static const struct bus_type node_subsys = {
        .name = "node",
        .dev_name = "node",
};

static inline ssize_t cpumap_read(struct file *file, struct kobject *kobj,
                                  const struct bin_attribute *attr, char *buf,
                                  loff_t off, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct node *node_dev = to_node(dev);
        cpumask_var_t mask;
        ssize_t n;

        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
                return 0;

        cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
        n = cpumap_print_bitmask_to_buf(buf, mask, off, count);
        free_cpumask_var(mask);

        return n;
}

static const BIN_ATTR_RO(cpumap, CPUMAP_FILE_MAX_BYTES);

static inline ssize_t cpulist_read(struct file *file, struct kobject *kobj,
                                   const struct bin_attribute *attr, char *buf,
                                   loff_t off, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct node *node_dev = to_node(dev);
        cpumask_var_t mask;
        ssize_t n;

        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
                return 0;

        cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
        n = cpumap_print_list_to_buf(buf, mask, off, count);
        free_cpumask_var(mask);

        return n;
}

static const BIN_ATTR_RO(cpulist, CPULIST_FILE_MAX_BYTES);

/**
 * struct node_access_nodes - Access class device to hold user visible
 *                            relationships to other nodes.
 * @dev:        Device for this memory access class
 * @list_node:  List element in the node's access list
 * @access:     The access class rank
 * @coord:      Heterogeneous memory performance coordinates
 */
struct node_access_nodes {
        struct device           dev;
        struct list_head        list_node;
        unsigned int            access;
#ifdef CONFIG_HMEM_REPORTING
        struct access_coordinate        coord;
#endif
};
#define to_access_nodes(dev) container_of(dev, struct node_access_nodes, dev)

static struct attribute *node_init_access_node_attrs[] = {
        NULL,
};

static struct attribute *node_targ_access_node_attrs[] = {
        NULL,
};

static const struct attribute_group initiators = {
        .name   = "initiators",
        .attrs  = node_init_access_node_attrs,
};

static const struct attribute_group targets = {
        .name   = "targets",
        .attrs  = node_targ_access_node_attrs,
};

static const struct attribute_group *node_access_node_groups[] = {
        &initiators,
        &targets,
        NULL,
};

#ifdef CONFIG_MEMORY_HOTPLUG
static BLOCKING_NOTIFIER_HEAD(node_chain);

int register_node_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&node_chain, nb);
}
EXPORT_SYMBOL(register_node_notifier);

void unregister_node_notifier(struct notifier_block *nb)
{
        blocking_notifier_chain_unregister(&node_chain, nb);
}
EXPORT_SYMBOL(unregister_node_notifier);

int node_notify(unsigned long val, void *v)
{
        return blocking_notifier_call_chain(&node_chain, val, v);
}
#endif

static void node_remove_accesses(struct node *node)
{
        struct node_access_nodes *c, *cnext;

        list_for_each_entry_safe(c, cnext, &node->access_list, list_node) {
                list_del(&c->list_node);
                device_unregister(&c->dev);
        }
}

static void node_access_release(struct device *dev)
{
        kfree(to_access_nodes(dev));
}

static struct node_access_nodes *node_init_node_access(struct node *node,
                                                       enum access_coordinate_class access)
{
        struct node_access_nodes *access_node;
        struct device *dev;

        list_for_each_entry(access_node, &node->access_list, list_node)
                if (access_node->access == access)
                        return access_node;

        access_node = kzalloc_obj(*access_node);
        if (!access_node)
                return NULL;

        access_node->access = access;
        dev = &access_node->dev;
        dev->parent = &node->dev;
        dev->release = node_access_release;
        dev->groups = node_access_node_groups;
        if (dev_set_name(dev, "access%u", access))
                goto free;

        if (device_register(dev))
                goto free_name;

        pm_runtime_no_callbacks(dev);
        list_add_tail(&access_node->list_node, &node->access_list);
        return access_node;
free_name:
        kfree_const(dev->kobj.name);
free:
        kfree(access_node);
        return NULL;
}

#ifdef CONFIG_HMEM_REPORTING
#define ACCESS_ATTR(property)                                           \
static ssize_t property##_show(struct device *dev,                      \
                           struct device_attribute *attr,               \
                           char *buf)                                   \
{                                                                       \
        return sysfs_emit(buf, "%u\n",                                  \
                          to_access_nodes(dev)->coord.property);        \
}                                                                       \
static DEVICE_ATTR_RO(property)

ACCESS_ATTR(read_bandwidth);
ACCESS_ATTR(read_latency);
ACCESS_ATTR(write_bandwidth);
ACCESS_ATTR(write_latency);

static struct attribute *access_attrs[] = {
        &dev_attr_read_bandwidth.attr,
        &dev_attr_read_latency.attr,
        &dev_attr_write_bandwidth.attr,
        &dev_attr_write_latency.attr,
        NULL,
};

/**
 * node_set_perf_attrs - Set the performance values for given access class
 * @nid: Node identifier to be set
 * @coord: Heterogeneous memory performance coordinates
 * @access: The access class the for the given attributes
 */
void node_set_perf_attrs(unsigned int nid, struct access_coordinate *coord,
                         enum access_coordinate_class access)
{
        struct node_access_nodes *c;
        struct node *node;
        int i;

        if (WARN_ON_ONCE(!node_online(nid)))
                return;

        node = node_devices[nid];
        c = node_init_node_access(node, access);
        if (!c)
                return;

        c->coord = *coord;
        for (i = 0; access_attrs[i] != NULL; i++) {
                if (sysfs_add_file_to_group(&c->dev.kobj, access_attrs[i],
                                            "initiators")) {
                        pr_info("failed to add performance attribute to node %d\n",
                                nid);
                        break;
                }
        }

        /* When setting CPU access coordinates, update mempolicy */
        if (access == ACCESS_COORDINATE_CPU) {
                if (mempolicy_set_node_perf(nid, coord)) {
                        pr_info("failed to set mempolicy attrs for node %d\n",
                                nid);
                }
        }
}
EXPORT_SYMBOL_GPL(node_set_perf_attrs);

/**
 * node_update_perf_attrs - Update the performance values for given access class
 * @nid: Node identifier to be updated
 * @coord: Heterogeneous memory performance coordinates
 * @access: The access class for the given attributes
 */
void node_update_perf_attrs(unsigned int nid, struct access_coordinate *coord,
                            enum access_coordinate_class access)
{
        struct node_access_nodes *access_node;
        struct node *node;
        int i;

        if (WARN_ON_ONCE(!node_online(nid)))
                return;

        node = node_devices[nid];
        list_for_each_entry(access_node, &node->access_list, list_node) {
                if (access_node->access != access)
                        continue;

                access_node->coord = *coord;
                for (i = 0; access_attrs[i]; i++) {
                        sysfs_notify(&access_node->dev.kobj,
                                     NULL, access_attrs[i]->name);
                }
                break;
        }

        /* When setting CPU access coordinates, update mempolicy */
        if (access != ACCESS_COORDINATE_CPU)
                return;

        if (mempolicy_set_node_perf(nid, coord))
                pr_info("failed to set mempolicy attrs for node %d\n", nid);
}
EXPORT_SYMBOL_GPL(node_update_perf_attrs);

/**
 * struct node_cache_info - Internal tracking for memory node caches
 * @dev:        Device represeting the cache level
 * @node:       List element for tracking in the node
 * @cache_attrs:Attributes for this cache level
 */
struct node_cache_info {
        struct device dev;
        struct list_head node;
        struct node_cache_attrs cache_attrs;
};
#define to_cache_info(device) container_of(device, struct node_cache_info, dev)

#define CACHE_ATTR(name, fmt)                                           \
static ssize_t name##_show(struct device *dev,                          \
                           struct device_attribute *attr,               \
                           char *buf)                                   \
{                                                                       \
        return sysfs_emit(buf, fmt "\n",                                \
                          to_cache_info(dev)->cache_attrs.name);        \
}                                                                       \
static DEVICE_ATTR_RO(name);

CACHE_ATTR(size, "%llu")
CACHE_ATTR(line_size, "%u")
CACHE_ATTR(indexing, "%u")
CACHE_ATTR(write_policy, "%u")
CACHE_ATTR(address_mode, "%#x")

static struct attribute *cache_attrs[] = {
        &dev_attr_indexing.attr,
        &dev_attr_size.attr,
        &dev_attr_line_size.attr,
        &dev_attr_write_policy.attr,
        &dev_attr_address_mode.attr,
        NULL,
};
ATTRIBUTE_GROUPS(cache);

static void node_cache_release(struct device *dev)
{
        kfree(dev);
}

static void node_cacheinfo_release(struct device *dev)
{
        struct node_cache_info *info = to_cache_info(dev);
        kfree(info);
}

static void node_init_cache_dev(struct node *node)
{
        struct device *dev;

        dev = kzalloc_obj(*dev);
        if (!dev)
                return;

        device_initialize(dev);
        dev->parent = &node->dev;
        dev->release = node_cache_release;
        if (dev_set_name(dev, "memory_side_cache"))
                goto put_device;

        if (device_add(dev))
                goto put_device;

        pm_runtime_no_callbacks(dev);
        node->cache_dev = dev;
        return;
put_device:
        put_device(dev);
}

/**
 * node_add_cache() - add cache attribute to a memory node
 * @nid: Node identifier that has new cache attributes
 * @cache_attrs: Attributes for the cache being added
 */
void node_add_cache(unsigned int nid, struct node_cache_attrs *cache_attrs)
{
        struct node_cache_info *info;
        struct device *dev;
        struct node *node;

        if (!node_online(nid) || !node_devices[nid])
                return;

        node = node_devices[nid];
        list_for_each_entry(info, &node->cache_attrs, node) {
                if (info->cache_attrs.level == cache_attrs->level) {
                        dev_warn(&node->dev,
                                "attempt to add duplicate cache level:%d\n",
                                cache_attrs->level);
                        return;
                }
        }

        if (!node->cache_dev)
                node_init_cache_dev(node);
        if (!node->cache_dev)
                return;

        info = kzalloc_obj(*info);
        if (!info)
                return;

        dev = &info->dev;
        device_initialize(dev);
        dev->parent = node->cache_dev;
        dev->release = node_cacheinfo_release;
        dev->groups = cache_groups;
        if (dev_set_name(dev, "index%d", cache_attrs->level))
                goto put_device;

        info->cache_attrs = *cache_attrs;
        if (device_add(dev)) {
                dev_warn(&node->dev, "failed to add cache level:%d\n",
                         cache_attrs->level);
                goto put_device;
        }
        pm_runtime_no_callbacks(dev);
        list_add_tail(&info->node, &node->cache_attrs);
        return;
put_device:
        put_device(dev);
}

static void node_remove_caches(struct node *node)
{
        struct node_cache_info *info, *next;

        if (!node->cache_dev)
                return;

        list_for_each_entry_safe(info, next, &node->cache_attrs, node) {
                list_del(&info->node);
                device_unregister(&info->dev);
        }
        device_unregister(node->cache_dev);
}

static void node_init_caches(unsigned int nid)
{
        INIT_LIST_HEAD(&node_devices[nid]->cache_attrs);
}
#else
static void node_init_caches(unsigned int nid) { }
static void node_remove_caches(struct node *node) { }
#endif

#define K(x) ((x) << (PAGE_SHIFT - 10))
static ssize_t node_read_meminfo(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        int len = 0;
        int nid = dev->id;
        struct pglist_data *pgdat = NODE_DATA(nid);
        struct sysinfo i;
        unsigned long sreclaimable, sunreclaimable;
        unsigned long swapcached = 0;

        si_meminfo_node(&i, nid);
        sreclaimable = node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B);
        sunreclaimable = node_page_state_pages(pgdat, NR_SLAB_UNRECLAIMABLE_B);
#ifdef CONFIG_SWAP
        swapcached = node_page_state_pages(pgdat, NR_SWAPCACHE);
#endif
        len = sysfs_emit_at(buf, len,
                            "Node %d MemTotal:       %8lu kB\n"
                            "Node %d MemFree:        %8lu kB\n"
                            "Node %d MemUsed:        %8lu kB\n"
                            "Node %d SwapCached:     %8lu kB\n"
                            "Node %d Active:         %8lu kB\n"
                            "Node %d Inactive:       %8lu kB\n"
                            "Node %d Active(anon):   %8lu kB\n"
                            "Node %d Inactive(anon): %8lu kB\n"
                            "Node %d Active(file):   %8lu kB\n"
                            "Node %d Inactive(file): %8lu kB\n"
                            "Node %d Unevictable:    %8lu kB\n"
                            "Node %d Mlocked:        %8lu kB\n",
                            nid, K(i.totalram),
                            nid, K(i.freeram),
                            nid, K(i.totalram - i.freeram),
                            nid, K(swapcached),
                            nid, K(node_page_state(pgdat, NR_ACTIVE_ANON) +
                                   node_page_state(pgdat, NR_ACTIVE_FILE)),
                            nid, K(node_page_state(pgdat, NR_INACTIVE_ANON) +
                                   node_page_state(pgdat, NR_INACTIVE_FILE)),
                            nid, K(node_page_state(pgdat, NR_ACTIVE_ANON)),
                            nid, K(node_page_state(pgdat, NR_INACTIVE_ANON)),
                            nid, K(node_page_state(pgdat, NR_ACTIVE_FILE)),
                            nid, K(node_page_state(pgdat, NR_INACTIVE_FILE)),
                            nid, K(node_page_state(pgdat, NR_UNEVICTABLE)),
                            nid, K(sum_zone_node_page_state(nid, NR_MLOCK)));

#ifdef CONFIG_HIGHMEM
        len += sysfs_emit_at(buf, len,
                             "Node %d HighTotal:      %8lu kB\n"
                             "Node %d HighFree:       %8lu kB\n"
                             "Node %d LowTotal:       %8lu kB\n"
                             "Node %d LowFree:        %8lu kB\n",
                             nid, K(i.totalhigh),
                             nid, K(i.freehigh),
                             nid, K(i.totalram - i.totalhigh),
                             nid, K(i.freeram - i.freehigh));
#endif
        len += sysfs_emit_at(buf, len,
                             "Node %d Dirty:          %8lu kB\n"
                             "Node %d Writeback:      %8lu kB\n"
                             "Node %d FilePages:      %8lu kB\n"
                             "Node %d Mapped:         %8lu kB\n"
                             "Node %d AnonPages:      %8lu kB\n"
                             "Node %d Shmem:          %8lu kB\n"
                             "Node %d KernelStack:    %8lu kB\n"
#ifdef CONFIG_SHADOW_CALL_STACK
                             "Node %d ShadowCallStack:%8lu kB\n"
#endif
                             "Node %d PageTables:     %8lu kB\n"
                             "Node %d SecPageTables:  %8lu kB\n"
                             "Node %d NFS_Unstable:   %8lu kB\n"
                             "Node %d Bounce:         %8lu kB\n"
                             "Node %d WritebackTmp:   %8lu kB\n"
                             "Node %d KReclaimable:   %8lu kB\n"
                             "Node %d Slab:           %8lu kB\n"
                             "Node %d SReclaimable:   %8lu kB\n"
                             "Node %d SUnreclaim:     %8lu kB\n"
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
                             "Node %d AnonHugePages:  %8lu kB\n"
                             "Node %d ShmemHugePages: %8lu kB\n"
                             "Node %d ShmemPmdMapped: %8lu kB\n"
                             "Node %d FileHugePages:  %8lu kB\n"
                             "Node %d FilePmdMapped:  %8lu kB\n"
#endif
#ifdef CONFIG_UNACCEPTED_MEMORY
                             "Node %d Unaccepted:     %8lu kB\n"
#endif
                             ,
                             nid, K(node_page_state(pgdat, NR_FILE_DIRTY)),
                             nid, K(node_page_state(pgdat, NR_WRITEBACK)),
                             nid, K(node_page_state(pgdat, NR_FILE_PAGES)),
                             nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
                             nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
                             nid, K(i.sharedram),
                             nid, node_page_state(pgdat, NR_KERNEL_STACK_KB),
#ifdef CONFIG_SHADOW_CALL_STACK
                             nid, node_page_state(pgdat, NR_KERNEL_SCS_KB),
#endif
                             nid, K(node_page_state(pgdat, NR_PAGETABLE)),
                             nid, K(node_page_state(pgdat, NR_SECONDARY_PAGETABLE)),
                             nid, 0UL,
                             nid, 0UL,
                             nid, 0UL,
                             nid, K(sreclaimable +
                                    node_page_state(pgdat, NR_KERNEL_MISC_RECLAIMABLE)),
                             nid, K(sreclaimable + sunreclaimable),
                             nid, K(sreclaimable),
                             nid, K(sunreclaimable)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
                             ,
                             nid, K(node_page_state(pgdat, NR_ANON_THPS)),
                             nid, K(node_page_state(pgdat, NR_SHMEM_THPS)),
                             nid, K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)),
                             nid, K(node_page_state(pgdat, NR_FILE_THPS)),
                             nid, K(node_page_state(pgdat, NR_FILE_PMDMAPPED))
#endif
#ifdef CONFIG_UNACCEPTED_MEMORY
                             ,
                             nid, K(sum_zone_node_page_state(nid, NR_UNACCEPTED))
#endif
                            );
        len += hugetlb_report_node_meminfo(buf, len, nid);
        return len;
}

#undef K
static DEVICE_ATTR(meminfo, 0444, node_read_meminfo, NULL);

static ssize_t node_read_numastat(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        fold_vm_numa_events();
        return sysfs_emit(buf,
                          "numa_hit %lu\n"
                          "numa_miss %lu\n"
                          "numa_foreign %lu\n"
                          "interleave_hit %lu\n"
                          "local_node %lu\n"
                          "other_node %lu\n",
                          sum_zone_numa_event_state(dev->id, NUMA_HIT),
                          sum_zone_numa_event_state(dev->id, NUMA_MISS),
                          sum_zone_numa_event_state(dev->id, NUMA_FOREIGN),
                          sum_zone_numa_event_state(dev->id, NUMA_INTERLEAVE_HIT),
                          sum_zone_numa_event_state(dev->id, NUMA_LOCAL),
                          sum_zone_numa_event_state(dev->id, NUMA_OTHER));
}
static DEVICE_ATTR(numastat, 0444, node_read_numastat, NULL);

static ssize_t node_read_vmstat(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        int nid = dev->id;
        struct pglist_data *pgdat = NODE_DATA(nid);
        int i;
        int len = 0;

        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
                len += sysfs_emit_at(buf, len, "%s %lu\n",
                                     zone_stat_name(i),
                                     sum_zone_node_page_state(nid, i));

#ifdef CONFIG_NUMA
        fold_vm_numa_events();
        for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
                len += sysfs_emit_at(buf, len, "%s %lu\n",
                                     numa_stat_name(i),
                                     sum_zone_numa_event_state(nid, i));

#endif
        for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
                unsigned long pages = node_page_state_pages(pgdat, i);

                if (vmstat_item_print_in_thp(i))
                        pages /= HPAGE_PMD_NR;
                len += sysfs_emit_at(buf, len, "%s %lu\n", node_stat_name(i),
                                     pages);
        }

        return len;
}
static DEVICE_ATTR(vmstat, 0444, node_read_vmstat, NULL);

static ssize_t node_read_distance(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        int nid = dev->id;
        int len = 0;
        int i;

        /*
         * buf is currently PAGE_SIZE in length and each node needs 4 chars
         * at the most (distance + space or newline).
         */
        BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);

        for_each_online_node(i) {
                len += sysfs_emit_at(buf, len, "%s%d",
                                     i ? " " : "", node_distance(nid, i));
        }

        len += sysfs_emit_at(buf, len, "\n");
        return len;
}
static DEVICE_ATTR(distance, 0444, node_read_distance, NULL);

static struct attribute *node_dev_attrs[] = {
        &dev_attr_meminfo.attr,
        &dev_attr_numastat.attr,
        &dev_attr_distance.attr,
        &dev_attr_vmstat.attr,
        NULL
};

static const struct bin_attribute *node_dev_bin_attrs[] = {
        &bin_attr_cpumap,
        &bin_attr_cpulist,
        NULL
};

static const struct attribute_group node_dev_group = {
        .attrs = node_dev_attrs,
        .bin_attrs = node_dev_bin_attrs,
};

static const struct attribute_group *node_dev_groups[] = {
        &node_dev_group,
#ifdef CONFIG_HAVE_ARCH_NODE_DEV_GROUP
        &arch_node_dev_group,
#endif
#ifdef CONFIG_MEMORY_FAILURE
        &memory_failure_attr_group,
#endif
        NULL
};

static void node_device_release(struct device *dev)
{
        kfree(to_node(dev));
}

struct node *node_devices[MAX_NUMNODES];

/*
 * register cpu under node
 */
int register_cpu_under_node(unsigned int cpu, unsigned int nid)
{
        int ret;
        struct device *obj;

        if (!node_online(nid))
                return 0;

        obj = get_cpu_device(cpu);
        if (!obj)
                return 0;

        ret = sysfs_create_link(&node_devices[nid]->dev.kobj,
                                &obj->kobj,
                                kobject_name(&obj->kobj));
        if (ret)
                return ret;

        return sysfs_create_link(&obj->kobj,
                                 &node_devices[nid]->dev.kobj,
                                 kobject_name(&node_devices[nid]->dev.kobj));
}

/**
 * register_memory_node_under_compute_node - link memory node to its compute
 *                                           node for a given access class.
 * @mem_nid:    Memory node number
 * @cpu_nid:    Cpu  node number
 * @access:     Access class to register
 *
 * Description:
 *      For use with platforms that may have separate memory and compute nodes.
 *      This function will export node relationships linking which memory
 *      initiator nodes can access memory targets at a given ranked access
 *      class.
 */
int register_memory_node_under_compute_node(unsigned int mem_nid,
                                            unsigned int cpu_nid,
                                            enum access_coordinate_class access)
{
        struct node *init_node, *targ_node;
        struct node_access_nodes *initiator, *target;
        int ret;

        if (!node_online(cpu_nid) || !node_online(mem_nid))
                return -ENODEV;

        init_node = node_devices[cpu_nid];
        targ_node = node_devices[mem_nid];
        initiator = node_init_node_access(init_node, access);
        target = node_init_node_access(targ_node, access);
        if (!initiator || !target)
                return -ENOMEM;

        ret = sysfs_add_link_to_group(&initiator->dev.kobj, "targets",
                                      &targ_node->dev.kobj,
                                      dev_name(&targ_node->dev));
        if (ret)
                return ret;

        ret = sysfs_add_link_to_group(&target->dev.kobj, "initiators",
                                      &init_node->dev.kobj,
                                      dev_name(&init_node->dev));
        if (ret)
                goto err;

        return 0;
 err:
        sysfs_remove_link_from_group(&initiator->dev.kobj, "targets",
                                     dev_name(&targ_node->dev));
        return ret;
}

int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
{
        struct device *obj;

        if (!node_online(nid))
                return 0;

        obj = get_cpu_device(cpu);
        if (!obj)
                return 0;

        sysfs_remove_link(&node_devices[nid]->dev.kobj,
                          kobject_name(&obj->kobj));
        sysfs_remove_link(&obj->kobj,
                          kobject_name(&node_devices[nid]->dev.kobj));

        return 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void do_register_memory_block_under_node(int nid,
                                                struct memory_block *mem_blk)
{
        int ret;

        ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
                                       &mem_blk->dev.kobj,
                                       kobject_name(&mem_blk->dev.kobj));
        if (ret && ret != -EEXIST)
                dev_err_ratelimited(&node_devices[nid]->dev,
                                    "can't create link to %s in sysfs (%d)\n",
                                    kobject_name(&mem_blk->dev.kobj), ret);

        ret = sysfs_create_link_nowarn(&mem_blk->dev.kobj,
                                &node_devices[nid]->dev.kobj,
                                kobject_name(&node_devices[nid]->dev.kobj));
        if (ret && ret != -EEXIST)
                dev_err_ratelimited(&mem_blk->dev,
                                    "can't create link to %s in sysfs (%d)\n",
                                    kobject_name(&node_devices[nid]->dev.kobj),
                                    ret);
}

/*
 * During hotplug we know that all pages in the memory block belong to the same
 * node.
 */
static int register_mem_block_under_node_hotplug(struct memory_block *mem_blk,
                                                 void *arg)
{
        int nid = *(int *)arg;

        do_register_memory_block_under_node(nid, mem_blk);
        return 0;
}

/*
 * Unregister a memory block device under the node it spans. Memory blocks
 * with multiple nodes cannot be offlined and therefore also never be removed.
 */
void unregister_memory_block_under_nodes(struct memory_block *mem_blk)
{
        if (mem_blk->nid == NUMA_NO_NODE)
                return;

        sysfs_remove_link(&node_devices[mem_blk->nid]->dev.kobj,
                          kobject_name(&mem_blk->dev.kobj));
        sysfs_remove_link(&mem_blk->dev.kobj,
                          kobject_name(&node_devices[mem_blk->nid]->dev.kobj));
}

/* register all memory blocks under the corresponding nodes */
static void register_memory_blocks_under_nodes(void)
{
        struct memblock_region *r;

        for_each_mem_region(r) {
                const unsigned long start_block_id = phys_to_block_id(r->base);
                const unsigned long end_block_id = phys_to_block_id(r->base + r->size - 1);
                const int nid = memblock_get_region_node(r);
                unsigned long block_id;

                if (!node_online(nid))
                        continue;

                for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
                        struct memory_block *mem;

                        mem = find_memory_block_by_id(block_id);
                        if (!mem)
                                continue;

                        memory_block_add_nid_early(mem, nid);
                        do_register_memory_block_under_node(nid, mem);
                        put_device(&mem->dev);
                }

        }
}

void register_memory_blocks_under_node_hotplug(int nid, unsigned long start_pfn,
                                               unsigned long end_pfn)
{
        walk_memory_blocks(PFN_PHYS(start_pfn), PFN_PHYS(end_pfn - start_pfn),
                           (void *)&nid, register_mem_block_under_node_hotplug);
        return;
}
#endif /* CONFIG_MEMORY_HOTPLUG */

/**
 * register_node - Initialize and register the node device.
 * @nid: Node number to use when creating the device.
 *
 * Return: 0 on success, -errno otherwise
 */
int register_node(int nid)
{
        int error;
        int cpu;
        struct node *node;

        node = kzalloc_obj(struct node);
        if (!node)
                return -ENOMEM;

        INIT_LIST_HEAD(&node->access_list);

        node->dev.id = nid;
        node->dev.bus = &node_subsys;
        node->dev.release = node_device_release;
        node->dev.groups = node_dev_groups;

        error = device_register(&node->dev);
        if (error) {
                put_device(&node->dev);
                return error;
        }

        node_devices[nid] = node;
        hugetlb_register_node(node);
        compaction_register_node(node);
        reclaim_register_node(node);

        /* link cpu under this node */
        for_each_present_cpu(cpu) {
                if (cpu_to_node(cpu) == nid)
                        register_cpu_under_node(cpu, nid);
        }

        node_init_caches(nid);

        return error;
}
/**
 * unregister_node - unregister a node device
 * @nid: nid of the node going away
 *
 * Unregisters the node device at node id @nid. All the devices on the
 * node must be unregistered before calling this function.
 */
void unregister_node(int nid)
{
        struct node *node = node_devices[nid];

        if (!node)
                return;

        hugetlb_unregister_node(node);
        compaction_unregister_node(node);
        reclaim_unregister_node(node);
        node_remove_accesses(node);
        node_remove_caches(node);
        device_unregister(&node->dev);
        node_devices[nid] = NULL;
}

/*
 * node states attributes
 */

struct node_attr {
        struct device_attribute attr;
        enum node_states state;
};

static ssize_t show_node_state(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct node_attr *na = container_of(attr, struct node_attr, attr);

        return sysfs_emit(buf, "%*pbl\n",
                          nodemask_pr_args(&node_states[na->state]));
}

#define _NODE_ATTR(name, state) \
        { __ATTR(name, 0444, show_node_state, NULL), state }

static struct node_attr node_state_attr[] = {
        [N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE),
        [N_ONLINE] = _NODE_ATTR(online, N_ONLINE),
        [N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
#ifdef CONFIG_HIGHMEM
        [N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
#endif
        [N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
        [N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
        [N_GENERIC_INITIATOR] = _NODE_ATTR(has_generic_initiator,
                                           N_GENERIC_INITIATOR),
};

static struct attribute *node_state_attrs[] = {
        &node_state_attr[N_POSSIBLE].attr.attr,
        &node_state_attr[N_ONLINE].attr.attr,
        &node_state_attr[N_NORMAL_MEMORY].attr.attr,
#ifdef CONFIG_HIGHMEM
        &node_state_attr[N_HIGH_MEMORY].attr.attr,
#endif
        &node_state_attr[N_MEMORY].attr.attr,
        &node_state_attr[N_CPU].attr.attr,
        &node_state_attr[N_GENERIC_INITIATOR].attr.attr,
        NULL
};

static const struct attribute_group memory_root_attr_group = {
        .attrs = node_state_attrs,
};

static const struct attribute_group *cpu_root_attr_groups[] = {
        &memory_root_attr_group,
        NULL,
};

void __init node_dev_init(void)
{
        int ret, i;

        BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
        BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);

        ret = subsys_system_register(&node_subsys, cpu_root_attr_groups);
        if (ret)
                panic("%s() failed to register subsystem: %d\n", __func__, ret);

        /*
         * Create all node devices, which will properly link the node
         * to already created cpu devices.
         */
        for_each_online_node(i) {
                ret =  register_node(i);
                if (ret)
                        panic("%s() failed to add node: %d\n", __func__, ret);
        }

        register_memory_blocks_under_nodes();
}