// SPDX-License-Identifier: GPL-2.0-only
/*
 * iteration_check.c: test races having to do with xarray iteration
 * Copyright (c) 2016 Intel Corporation
 * Author: Ross Zwisler <ross.zwisler@linux.intel.com>
 */
#include <pthread.h>
#include "test.h"

#define NUM_THREADS     5
#define MAX_IDX         100
#define TAG             XA_MARK_0
#define NEW_TAG         XA_MARK_1

static pthread_t threads[NUM_THREADS];
static unsigned int seeds[3];
static DEFINE_XARRAY(array);
static bool test_complete;
static int max_order;

void my_item_insert(struct xarray *xa, unsigned long index)
{
        XA_STATE(xas, xa, index);
        struct item *item = item_create(index, 0);
        int order;

retry:
        xas_lock(&xas);
        for (order = max_order; order >= 0; order--) {
                xas_set_order(&xas, index, order);
                item->order = order;
                if (xas_find_conflict(&xas))
                        continue;
                xas_store(&xas, item);
                xas_set_mark(&xas, TAG);
                break;
        }
        xas_unlock(&xas);
        if (xas_nomem(&xas, GFP_KERNEL))
                goto retry;
        if (order < 0)
                free(item);
}

/* relentlessly fill the array with tagged entries */
static void *add_entries_fn(void *arg)
{
        rcu_register_thread();

        while (!test_complete) {
                unsigned long pgoff;

                for (pgoff = 0; pgoff < MAX_IDX; pgoff++) {
                        my_item_insert(&array, pgoff);
                }
        }

        rcu_unregister_thread();

        return NULL;
}

/*
 * Iterate over tagged entries, retrying when we find ourselves in a deleted
 * node and randomly pausing the iteration.
 */
static void *tagged_iteration_fn(void *arg)
{
        XA_STATE(xas, &array, 0);
        void *entry;

        rcu_register_thread();

        while (!test_complete) {
                xas_set(&xas, 0);
                rcu_read_lock();
                xas_for_each_marked(&xas, entry, ULONG_MAX, TAG) {
                        if (xas_retry(&xas, entry))
                                continue;

                        if (rand_r(&seeds[0]) % 50 == 0) {
                                xas_pause(&xas);
                                rcu_read_unlock();
                                rcu_barrier();
                                rcu_read_lock();
                        }
                }
                rcu_read_unlock();
        }

        rcu_unregister_thread();

        return NULL;
}

/*
 * Iterate over the entries, retrying when we find ourselves in a deleted
 * node and randomly pausing the iteration.
 */
static void *untagged_iteration_fn(void *arg)
{
        XA_STATE(xas, &array, 0);
        void *entry;

        rcu_register_thread();

        while (!test_complete) {
                xas_set(&xas, 0);
                rcu_read_lock();
                xas_for_each(&xas, entry, ULONG_MAX) {
                        if (xas_retry(&xas, entry))
                                continue;

                        if (rand_r(&seeds[1]) % 50 == 0) {
                                xas_pause(&xas);
                                rcu_read_unlock();
                                rcu_barrier();
                                rcu_read_lock();
                        }
                }
                rcu_read_unlock();
        }

        rcu_unregister_thread();

        return NULL;
}

/*
 * Randomly remove entries to help induce retries in the
 * two iteration functions.
 */
static void *remove_entries_fn(void *arg)
{
        rcu_register_thread();

        while (!test_complete) {
                int pgoff;
                struct item *item;

                pgoff = rand_r(&seeds[2]) % MAX_IDX;

                item = xa_erase(&array, pgoff);
                if (item)
                        item_free(item, pgoff);
        }

        rcu_unregister_thread();

        return NULL;
}

static void *tag_entries_fn(void *arg)
{
        rcu_register_thread();

        while (!test_complete) {
                tag_tagged_items(&array, 0, MAX_IDX, 10, TAG, NEW_TAG);
        }
        rcu_unregister_thread();
        return NULL;
}

/* This is a unit test for a bug found by the syzkaller tester */
void iteration_test(unsigned order, unsigned test_duration)
{
        int i;

        printv(1, "Running %siteration tests for %d seconds\n",
                        order > 0 ? "multiorder " : "", test_duration);

        max_order = order;
        test_complete = false;

        for (i = 0; i < 3; i++)
                seeds[i] = rand();

        if (pthread_create(&threads[0], NULL, tagged_iteration_fn, NULL)) {
                perror("create tagged iteration thread");
                exit(1);
        }
        if (pthread_create(&threads[1], NULL, untagged_iteration_fn, NULL)) {
                perror("create untagged iteration thread");
                exit(1);
        }
        if (pthread_create(&threads[2], NULL, add_entries_fn, NULL)) {
                perror("create add entry thread");
                exit(1);
        }
        if (pthread_create(&threads[3], NULL, remove_entries_fn, NULL)) {
                perror("create remove entry thread");
                exit(1);
        }
        if (pthread_create(&threads[4], NULL, tag_entries_fn, NULL)) {
                perror("create tag entry thread");
                exit(1);
        }

        sleep(test_duration);
        test_complete = true;

        for (i = 0; i < NUM_THREADS; i++) {
                if (pthread_join(threads[i], NULL)) {
                        perror("pthread_join");
                        exit(1);
                }
        }

        item_kill_tree(&array);
}