netdata/collectors/ebpf.plugin/ebpf_swap.c

// SPDX-License-Identifier: GPL-3.0-or-later

#include "ebpf.h"
#include "ebpf_swap.h"

static char *swap_dimension_name[NETDATA_SWAP_END] = { "read", "write" };
static netdata_syscall_stat_t swap_aggregated_data[NETDATA_SWAP_END];
static netdata_publish_syscall_t swap_publish_aggregated[NETDATA_SWAP_END];

static int read_thread_closed = 1;
netdata_publish_swap_t *swap_vector = NULL;

static netdata_idx_t swap_hash_values[NETDATA_SWAP_END];
static netdata_idx_t *swap_values = NULL;

netdata_publish_swap_t **swap_pid = NULL;

struct config swap_config = { .first_section = NULL,
    .last_section = NULL,
    .mutex = NETDATA_MUTEX_INITIALIZER,
    .index = { .avl_tree = { .root = NULL, .compar = appconfig_section_compare },
        .rwlock = AVL_LOCK_INITIALIZER } };

static ebpf_local_maps_t swap_maps[] = {{.name = "tbl_pid_swap", .internal_input = ND_EBPF_DEFAULT_PID_SIZE,
                                         .user_input = 0,
                                         .type = NETDATA_EBPF_MAP_RESIZABLE | NETDATA_EBPF_MAP_PID,
                                         .map_fd = ND_EBPF_MAP_FD_NOT_INITIALIZED},
                                        {.name = "swap_ctrl", .internal_input = NETDATA_CONTROLLER_END,
                                         .user_input = 0,
                                         .type = NETDATA_EBPF_MAP_CONTROLLER,
                                         .map_fd = ND_EBPF_MAP_FD_NOT_INITIALIZED},
                                        {.name = "tbl_swap", .internal_input = NETDATA_SWAP_END,
                                         .user_input = 0,
                                         .type = NETDATA_EBPF_MAP_STATIC,
                                         .map_fd = ND_EBPF_MAP_FD_NOT_INITIALIZED},
                                        {.name = NULL, .internal_input = 0, .user_input = 0}};

static struct bpf_link **probe_links = NULL;
static struct bpf_object *objects = NULL;

struct netdata_static_thread swap_threads = {"SWAP KERNEL", NULL, NULL, 1,
                                             NULL, NULL,  NULL};

/*****************************************************************
 *
 *  FUNCTIONS TO CLOSE THE THREAD
 *
 *****************************************************************/

/**
 * Clean swap structure
 */
void clean_swap_pid_structures() {
    struct pid_stat *pids = root_of_pids;
    while (pids) {
        freez(swap_pid[pids->pid]);

        pids = pids->next;
    }
}

/**
 * Clean up the main thread.
 *
 * @param ptr thread data.
 */
static void ebpf_swap_cleanup(void *ptr)
{
    ebpf_module_t *em = (ebpf_module_t *)ptr;
    if (!em->enabled)
        return;

    heartbeat_t hb;
    heartbeat_init(&hb);
    uint32_t tick = 2 * USEC_PER_MS;
    while (!read_thread_closed) {
        usec_t dt = heartbeat_next(&hb, tick);
        UNUSED(dt);
    }

    ebpf_cleanup_publish_syscall(swap_publish_aggregated);

    freez(swap_vector);
    freez(swap_values);

    if (probe_links) {
        struct bpf_program *prog;
        size_t i = 0 ;
        bpf_object__for_each_program(prog, objects) {
            bpf_link__destroy(probe_links[i]);
            i++;
        }
        bpf_object__close(objects);
    }
}

/*****************************************************************
 *
 *  COLLECTOR THREAD
 *
 *****************************************************************/

/**
 * Apps Accumulator
 *
 * Sum all values read from kernel and store in the first address.
 *
 * @param out the vector with read values.
 */
static void swap_apps_accumulator(netdata_publish_swap_t *out)
{
    int i, end = (running_on_kernel >= NETDATA_KERNEL_V4_15) ? ebpf_nprocs : 1;
    netdata_publish_swap_t *total = &out[0];
    for (i = 1; i < end; i++) {
        netdata_publish_swap_t *w = &out[i];
        total->write += w->write;
        total->read += w->read;
    }
}

/**
 * Fill PID
 *
 * Fill PID structures
 *
 * @param current_pid pid that we are collecting data
 * @param out         values read from hash tables;
 */
static void swap_fill_pid(uint32_t current_pid, netdata_publish_swap_t *publish)
{
    netdata_publish_swap_t *curr = swap_pid[current_pid];
    if (!curr) {
        curr = callocz(1, sizeof(netdata_publish_swap_t));
        swap_pid[current_pid] = curr;
    }

    memcpy(curr, publish, sizeof(netdata_publish_swap_t));
}

/**
 * Update cgroup
 *
 * Update cgroup data based in
 */
static void ebpf_update_swap_cgroup()
{
    ebpf_cgroup_target_t *ect ;
    netdata_publish_swap_t *cv = swap_vector;
    int fd = swap_maps[NETDATA_PID_SWAP_TABLE].map_fd;
    size_t length = sizeof(netdata_publish_swap_t)*ebpf_nprocs;
    pthread_mutex_lock(&mutex_cgroup_shm);
    for (ect = ebpf_cgroup_pids; ect; ect = ect->next) {
        struct pid_on_target2 *pids;
        for (pids = ect->pids; pids; pids = pids->next) {
            int pid = pids->pid;
            netdata_publish_swap_t *out = &pids->swap;
            if (likely(swap_pid) && swap_pid[pid]) {
                netdata_publish_swap_t *in = swap_pid[pid];

                memcpy(out, in, sizeof(netdata_publish_swap_t));
            } else {
                memset(cv, 0, length);
                if (!bpf_map_lookup_elem(fd, &pid, cv)) {
                    swap_apps_accumulator(cv);

                    memcpy(out, cv, sizeof(netdata_publish_swap_t));
                }
            }
        }
    }
    pthread_mutex_unlock(&mutex_cgroup_shm);
}

/**
 * Read APPS table
 *
 * Read the apps table and store data inside the structure.
 */
static void read_apps_table()
{
    netdata_publish_swap_t *cv = swap_vector;
    uint32_t key;
    struct pid_stat *pids = root_of_pids;
    int fd = swap_maps[NETDATA_PID_SWAP_TABLE].map_fd;
    size_t length = sizeof(netdata_publish_swap_t)*ebpf_nprocs;
    while (pids) {
        key = pids->pid;

        if (bpf_map_lookup_elem(fd, &key, cv)) {
            pids = pids->next;
            continue;
        }

        swap_apps_accumulator(cv);

        swap_fill_pid(key, cv);

        // We are cleaning to avoid passing data read from one process to other.
        memset(cv, 0, length);

        pids = pids->next;
    }
}

/**
* Send global
*
* Send global charts to Netdata
*/
static void swap_send_global()
{
    write_io_chart(NETDATA_MEM_SWAP_CHART, NETDATA_EBPF_SYSTEM_GROUP,
                   swap_publish_aggregated[NETDATA_KEY_SWAP_WRITEPAGE_CALL].dimension,
                   (long long) swap_hash_values[NETDATA_KEY_SWAP_WRITEPAGE_CALL],
                   swap_publish_aggregated[NETDATA_KEY_SWAP_READPAGE_CALL].dimension,
                   (long long) swap_hash_values[NETDATA_KEY_SWAP_READPAGE_CALL]);
}

/**
 * Read global counter
 *
 * Read the table with number of calls to all functions
 */
static void read_global_table()
{
    netdata_idx_t *stored = swap_values;
    netdata_idx_t *val = swap_hash_values;
    int fd = swap_maps[NETDATA_SWAP_GLOBAL_TABLE].map_fd;

    uint32_t i, end = NETDATA_SWAP_END;
    for (i = NETDATA_KEY_SWAP_READPAGE_CALL; i < end; i++) {
        if (!bpf_map_lookup_elem(fd, &i, stored)) {
            int j;
            int last = ebpf_nprocs;
            netdata_idx_t total = 0;
            for (j = 0; j < last; j++)
                total += stored[j];

            val[i] = total;
        }
    }
}

/**
 * Swap read hash
 *
 * This is the thread callback.
 *
 * @param ptr It is a NULL value for this thread.
 *
 * @return It always returns NULL.
 */
void *ebpf_swap_read_hash(void *ptr)
{
    read_thread_closed = 0;

    heartbeat_t hb;
    heartbeat_init(&hb);

    ebpf_module_t *em = (ebpf_module_t *)ptr;
    usec_t step = NETDATA_SWAP_SLEEP_MS * em->update_every;
    while (!close_ebpf_plugin) {
        usec_t dt = heartbeat_next(&hb, step);
        (void)dt;

        read_global_table();
    }

    read_thread_closed = 1;
    return NULL;
}

/**
 * Sum PIDs
 *
 * Sum values for all targets.
 *
 * @param swap
 * @param root
 */
static void ebpf_swap_sum_pids(netdata_publish_swap_t *swap, struct pid_on_target *root)
{
    uint64_t local_read = 0;
    uint64_t local_write = 0;

    while (root) {
        int32_t pid = root->pid;
        netdata_publish_swap_t *w = swap_pid[pid];
        if (w) {
            local_write += w->write;
            local_read += w->read;
        }
        root = root->next;
    }

    // These conditions were added, because we are using incremental algorithm
    swap->write = (local_write >= swap->write) ? local_write : swap->write;
    swap->read = (local_read >= swap->read) ? local_read : swap->read;
}

/**
 * Send data to Netdata calling auxiliary functions.
 *
 * @param root the target list.
*/
void ebpf_swap_send_apps_data(struct target *root)
{
    struct target *w;
    for (w = root; w; w = w->next) {
        if (unlikely(w->exposed && w->processes)) {
            ebpf_swap_sum_pids(&w->swap, w->root_pid);
        }
    }

    write_begin_chart(NETDATA_APPS_FAMILY, NETDATA_MEM_SWAP_READ_CHART);
    for (w = root; w; w = w->next) {
        if (unlikely(w->exposed && w->processes)) {
            write_chart_dimension(w->name, (long long) w->swap.read);
        }
    }
    write_end_chart();

    write_begin_chart(NETDATA_APPS_FAMILY, NETDATA_MEM_SWAP_WRITE_CHART);
    for (w = root; w; w = w->next) {
        if (unlikely(w->exposed && w->processes)) {
            write_chart_dimension(w->name, (long long) w->swap.write);
        }
    }
    write_end_chart();
}

/**
 * Sum PIDs
 *
 * Sum values for all targets.
 *
 * @param swap
 * @param root
 */
static void ebpf_swap_sum_cgroup_pids(netdata_publish_swap_t *swap, struct pid_on_target2 *pids)
{
    uint64_t local_read = 0;
    uint64_t local_write = 0;

    while (pids) {
        netdata_publish_swap_t *w = &pids->swap;
        local_write += w->write;
        local_read += w->read;

        pids = pids->next;
    }

    // These conditions were added, because we are using incremental algorithm
    swap->write = (local_write >= swap->write) ? local_write : swap->write;
    swap->read = (local_read >= swap->read) ? local_read : swap->read;
}

/**
 * Send Systemd charts
 *
 * Send collected data to Netdata.
 *
 * @return It returns the status for chart creation, if it is necessary to remove a specific dimension, zero is returned
 *         otherwise function returns 1 to avoid chart recreation
 */
static int ebpf_send_systemd_swap_charts()
{
    int ret = 1;
    ebpf_cgroup_target_t *ect;
    write_begin_chart(NETDATA_SERVICE_FAMILY, NETDATA_MEM_SWAP_READ_CHART);
    for (ect = ebpf_cgroup_pids; ect ; ect = ect->next) {
        if (unlikely(ect->systemd) && unlikely(ect->updated)) {
            write_chart_dimension(ect->name, (long long) ect->publish_systemd_swap.read);
        } else
            ret = 0;
    }
    write_end_chart();

    write_begin_chart(NETDATA_SERVICE_FAMILY, NETDATA_MEM_SWAP_WRITE_CHART);
    for (ect = ebpf_cgroup_pids; ect ; ect = ect->next) {
        if (unlikely(ect->systemd) && unlikely(ect->updated)) {
            write_chart_dimension(ect->name, (long long) ect->publish_systemd_swap.write);
        }
    }
    write_end_chart();

    return ret;
}

/**
 * Create specific swap charts
 *
 * Create charts for cgroup/application.
 *
 * @param type the chart type.
 * @param update_every value to overwrite the update frequency set by the server.
 */
static void ebpf_create_specific_swap_charts(char *type, int update_every)
{
    ebpf_create_chart(type, NETDATA_MEM_SWAP_READ_CHART,
                      "Calls to function <code>swap_readpage</code>.",
                      EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_CGROUP_SWAP_SUBMENU,
                      NETDATA_CGROUP_SWAP_READ_CONTEXT, NETDATA_EBPF_CHART_TYPE_LINE,
                      NETDATA_CHART_PRIO_CGROUPS_CONTAINERS + 5100,
                      ebpf_create_global_dimension,
                      swap_publish_aggregated, 1, update_every, NETDATA_EBPF_MODULE_NAME_SWAP);

    ebpf_create_chart(type, NETDATA_MEM_SWAP_WRITE_CHART,
                      "Calls to function <code>swap_writepage</code>.",
                      EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_CGROUP_SWAP_SUBMENU,
                      NETDATA_CGROUP_SWAP_WRITE_CONTEXT, NETDATA_EBPF_CHART_TYPE_LINE,
                      NETDATA_CHART_PRIO_CGROUPS_CONTAINERS + 5101,
                      ebpf_create_global_dimension,
                      &swap_publish_aggregated[NETDATA_KEY_SWAP_WRITEPAGE_CALL], 1,
                      update_every, NETDATA_EBPF_MODULE_NAME_SWAP);
}

/**
 * Create specific swap charts
 *
 * Create charts for cgroup/application.
 *
 * @param type the chart type.
 * @param update_every value to overwrite the update frequency set by the server.
 */
static void ebpf_obsolete_specific_swap_charts(char *type, int update_every)
{
    ebpf_write_chart_obsolete(type, NETDATA_MEM_SWAP_READ_CHART,"Calls to function <code>swap_readpage</code>.",
                              EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_CGROUP_SWAP_SUBMENU,
                              NETDATA_EBPF_CHART_TYPE_LINE, NETDATA_CGROUP_SWAP_READ_CONTEXT,
                              NETDATA_CHART_PRIO_CGROUPS_CONTAINERS + 5100, update_every);

    ebpf_write_chart_obsolete(type, NETDATA_MEM_SWAP_WRITE_CHART, "Calls to function <code>swap_writepage</code>.",
                              EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_CGROUP_SWAP_SUBMENU,
                              NETDATA_EBPF_CHART_TYPE_LINE, NETDATA_CGROUP_SWAP_WRITE_CONTEXT,
                              NETDATA_CHART_PRIO_CGROUPS_CONTAINERS + 5101, update_every);
}

/*
 * Send Specific Swap data
 *
 * Send data for specific cgroup/apps.
 *
 * @param type   chart type
 * @param values structure with values that will be sent to netdata
 */
static void ebpf_send_specific_swap_data(char *type, netdata_publish_swap_t *values)
{
    write_begin_chart(type, NETDATA_MEM_SWAP_READ_CHART);
    write_chart_dimension(swap_publish_aggregated[NETDATA_KEY_SWAP_READPAGE_CALL].name, (long long) values->read);
    write_end_chart();

    write_begin_chart(type, NETDATA_MEM_SWAP_WRITE_CHART);
    write_chart_dimension(swap_publish_aggregated[NETDATA_KEY_SWAP_WRITEPAGE_CALL].name, (long long) values->write);
    write_end_chart();
}

/**
 *  Create Systemd Swap Charts
 *
 *  Create charts when systemd is enabled
 *
 *  @param update_every value to overwrite the update frequency set by the server.
 **/
static void ebpf_create_systemd_swap_charts(int update_every)
{
    ebpf_create_charts_on_systemd(NETDATA_MEM_SWAP_READ_CHART,
                                  "Calls to <code>swap_readpage</code>.",
                                  EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_CGROUP_SWAP_SUBMENU,
                                  NETDATA_EBPF_CHART_TYPE_STACKED, 20191,
                                  ebpf_algorithms[NETDATA_EBPF_INCREMENTAL_IDX], NETDATA_SYSTEMD_SWAP_READ_CONTEXT,
                                  NETDATA_EBPF_MODULE_NAME_SWAP, update_every);

    ebpf_create_charts_on_systemd(NETDATA_MEM_SWAP_WRITE_CHART,
                                  "Calls to function <code>swap_writepage</code>.",
                                  EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_CGROUP_SWAP_SUBMENU,
                                  NETDATA_EBPF_CHART_TYPE_STACKED, 20192,
                                  ebpf_algorithms[NETDATA_EBPF_INCREMENTAL_IDX], NETDATA_SYSTEMD_SWAP_WRITE_CONTEXT,
                                  NETDATA_EBPF_MODULE_NAME_SWAP, update_every);
}

/**
 * Send data to Netdata calling auxiliary functions.
 *
 * @param update_every value to overwrite the update frequency set by the server.
*/
void ebpf_swap_send_cgroup_data(int update_every)
{
    if (!ebpf_cgroup_pids)
        return;

    pthread_mutex_lock(&mutex_cgroup_shm);
    ebpf_cgroup_target_t *ect;
    for (ect = ebpf_cgroup_pids; ect ; ect = ect->next) {
        ebpf_swap_sum_cgroup_pids(&ect->publish_systemd_swap, ect->pids);
    }

    int has_systemd = shm_ebpf_cgroup.header->systemd_enabled;

    if (has_systemd) {
        static int systemd_charts = 0;
        if (!systemd_charts) {
            ebpf_create_systemd_swap_charts(update_every);
            systemd_charts = 1;
            fflush(stdout);
        }

        systemd_charts = ebpf_send_systemd_swap_charts();
    }

    for (ect = ebpf_cgroup_pids; ect ; ect = ect->next) {
        if (ect->systemd)
            continue;

        if (!(ect->flags & NETDATA_EBPF_CGROUP_HAS_SWAP_CHART) && ect->updated) {
            ebpf_create_specific_swap_charts(ect->name, update_every);
            ect->flags |= NETDATA_EBPF_CGROUP_HAS_SWAP_CHART;
        }

        if (ect->flags & NETDATA_EBPF_CGROUP_HAS_SWAP_CHART) {
            if (ect->updated) {
                ebpf_send_specific_swap_data(ect->name, &ect->publish_systemd_swap);
            } else {
                ebpf_obsolete_specific_swap_charts(ect->name, update_every);
                ect->flags &= ~NETDATA_EBPF_CGROUP_HAS_SWAP_CHART;
            }
        }
    }

    pthread_mutex_unlock(&mutex_cgroup_shm);
}

/**
* Main loop for this collector.
*/
static void swap_collector(ebpf_module_t *em)
{
    swap_threads.thread = mallocz(sizeof(netdata_thread_t));
    swap_threads.start_routine = ebpf_swap_read_hash;

    netdata_thread_create(swap_threads.thread, swap_threads.name, NETDATA_THREAD_OPTION_JOINABLE,
                          ebpf_swap_read_hash, em);

    int apps = em->apps_charts;
    int cgroup = em->cgroup_charts;
    int update_every = em->update_every;
    int counter = update_every - 1;
    while (!close_ebpf_plugin) {
        pthread_mutex_lock(&collect_data_mutex);
        pthread_cond_wait(&collect_data_cond_var, &collect_data_mutex);

        if (++counter == update_every) {
            counter = 0;
            if (apps)
                read_apps_table();

            if (cgroup)
                ebpf_update_swap_cgroup();

            pthread_mutex_lock(&lock);

            swap_send_global();

            if (apps)
                ebpf_swap_send_apps_data(apps_groups_root_target);

            if (cgroup)
                ebpf_swap_send_cgroup_data(update_every);

            pthread_mutex_unlock(&lock);
        }
        pthread_mutex_unlock(&collect_data_mutex);
    }
}

/*****************************************************************
 *
 *  INITIALIZE THREAD
 *
 *****************************************************************/

/**
 * Create apps charts
 *
 * Call ebpf_create_chart to create the charts on apps submenu.
 *
 * @param em a pointer to the structure with the default values.
 */
void ebpf_swap_create_apps_charts(struct ebpf_module *em, void *ptr)
{
    struct target *root = ptr;
    ebpf_create_charts_on_apps(NETDATA_MEM_SWAP_READ_CHART,
                               "Calls to function <code>swap_readpage</code>.",
                               EBPF_COMMON_DIMENSION_CALL,
                               NETDATA_SWAP_SUBMENU,
                               NETDATA_EBPF_CHART_TYPE_STACKED,
                               20191,
                               ebpf_algorithms[NETDATA_EBPF_INCREMENTAL_IDX],
                               root, em->update_every, NETDATA_EBPF_MODULE_NAME_SWAP);

    ebpf_create_charts_on_apps(NETDATA_MEM_SWAP_WRITE_CHART,
                               "Calls to function <code>swap_writepage</code>.",
                               EBPF_COMMON_DIMENSION_CALL,
                               NETDATA_SWAP_SUBMENU,
                               NETDATA_EBPF_CHART_TYPE_STACKED,
                               20192,
                               ebpf_algorithms[NETDATA_EBPF_INCREMENTAL_IDX],
                               root, em->update_every, NETDATA_EBPF_MODULE_NAME_SWAP);
}

/**
 * Allocate vectors used with this thread.
 *
 * We are not testing the return, because callocz does this and shutdown the software
 * case it was not possible to allocate.
 *
 * @param apps is apps enabled?
 */
static void ebpf_swap_allocate_global_vectors(int apps)
{
    if (apps)
        swap_pid = callocz((size_t)pid_max, sizeof(netdata_publish_swap_t *));

    swap_vector = callocz((size_t)ebpf_nprocs, sizeof(netdata_publish_swap_t));

    swap_values = callocz((size_t)ebpf_nprocs, sizeof(netdata_idx_t));

    memset(swap_hash_values, 0, sizeof(swap_hash_values));
}

/*****************************************************************
 *
 *  MAIN THREAD
 *
 *****************************************************************/

/**
 * Create global charts
 *
 * Call ebpf_create_chart to create the charts for the collector.
 *
 * @param update_every value to overwrite the update frequency set by the server.
 */
static void ebpf_create_swap_charts(int update_every)
{
    ebpf_create_chart(NETDATA_EBPF_SYSTEM_GROUP, NETDATA_MEM_SWAP_CHART,
                      "Calls to access swap memory",
                      EBPF_COMMON_DIMENSION_CALL, NETDATA_SYSTEM_SWAP_SUBMENU,
                      NULL,
                      NETDATA_EBPF_CHART_TYPE_LINE,
                      202,
                      ebpf_create_global_dimension,
                      swap_publish_aggregated, NETDATA_SWAP_END,
                      update_every, NETDATA_EBPF_MODULE_NAME_SWAP);
}

/**
 * SWAP thread
 *
 * Thread used to make swap thread
 *
 * @param ptr a pointer to `struct ebpf_module`
 *
 * @return It always return NULL
 */
void *ebpf_swap_thread(void *ptr)
{
    netdata_thread_cleanup_push(ebpf_swap_cleanup, ptr);

    ebpf_module_t *em = (ebpf_module_t *)ptr;
    em->maps = swap_maps;

    ebpf_update_pid_table(&swap_maps[NETDATA_PID_SWAP_TABLE], em);

    if (!em->enabled)
        goto endswap;

    probe_links = ebpf_load_program(ebpf_plugin_dir, em, running_on_kernel, isrh, &objects);
    if (!probe_links) {
        em->enabled = CONFIG_BOOLEAN_NO;
        goto endswap;
    }

    ebpf_swap_allocate_global_vectors(em->apps_charts);

    int algorithms[NETDATA_SWAP_END] = { NETDATA_EBPF_INCREMENTAL_IDX, NETDATA_EBPF_INCREMENTAL_IDX };
    ebpf_global_labels(swap_aggregated_data, swap_publish_aggregated, swap_dimension_name, swap_dimension_name,
                       algorithms, NETDATA_SWAP_END);

    pthread_mutex_lock(&lock);
    ebpf_create_swap_charts(em->update_every);
    ebpf_update_stats(&plugin_statistics, em);
    pthread_mutex_unlock(&lock);

    swap_collector(em);

endswap:
    if (!em->enabled)
        ebpf_update_disabled_plugin_stats(em);

    netdata_thread_cleanup_pop(1);
    return NULL;
}