// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/interval_tree.h>
#include <linux/prandom.h>
#include <linux/slab.h>
#include <asm/timex.h>
#include <linux/bitmap.h>
#include <linux/maple_tree.h>

#define __param(type, name, init, msg)          \
        static type name = init;                \
        module_param(name, type, 0444);         \
        MODULE_PARM_DESC(name, msg);

__param(int, nnodes, 100, "Number of nodes in the interval tree");
__param(int, perf_loops, 1000, "Number of iterations modifying the tree");

__param(int, nsearches, 100, "Number of searches to the interval tree");
__param(int, search_loops, 1000, "Number of iterations searching the tree");
__param(bool, search_all, false, "Searches will iterate all nodes in the tree");

__param(uint, max_endpoint, ~0, "Largest value for the interval's endpoint");
__param(ullong, seed, 3141592653589793238ULL, "Random seed");

static struct rb_root_cached root = RB_ROOT_CACHED;
static struct interval_tree_node *nodes = NULL;
static u32 *queries = NULL;

static struct rnd_state rnd;

static inline unsigned long
search(struct rb_root_cached *root, unsigned long start, unsigned long last)
{
        struct interval_tree_node *node;
        unsigned long results = 0;

        for (node = interval_tree_iter_first(root, start, last); node;
             node = interval_tree_iter_next(node, start, last))
                results++;
        return results;
}

static void init(void)
{
        int i;

        for (i = 0; i < nnodes; i++) {
                u32 b = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
                u32 a = (prandom_u32_state(&rnd) >> 4) % b;

                nodes[i].start = a;
                nodes[i].last = b;
        }

        /*
         * Limit the search scope to what the user defined.
         * Otherwise we are merely measuring empty walks,
         * which is pointless.
         */
        for (i = 0; i < nsearches; i++)
                queries[i] = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
}

static int basic_check(void)
{
        int i, j;
        cycles_t time1, time2, time;

        printk(KERN_ALERT "interval tree insert/remove");

        init();

        time1 = get_cycles();

        for (i = 0; i < perf_loops; i++) {
                for (j = 0; j < nnodes; j++)
                        interval_tree_insert(nodes + j, &root);
                for (j = 0; j < nnodes; j++)
                        interval_tree_remove(nodes + j, &root);
        }

        time2 = get_cycles();
        time = time2 - time1;

        time = div_u64(time, perf_loops);
        printk(" -> %llu cycles\n", (unsigned long long)time);

        return 0;
}

static int search_check(void)
{
        int i, j;
        unsigned long results;
        cycles_t time1, time2, time;

        printk(KERN_ALERT "interval tree search");

        init();

        for (j = 0; j < nnodes; j++)
                interval_tree_insert(nodes + j, &root);

        time1 = get_cycles();

        results = 0;
        for (i = 0; i < search_loops; i++)
                for (j = 0; j < nsearches; j++) {
                        unsigned long start = search_all ? 0 : queries[j];
                        unsigned long last = search_all ? max_endpoint : queries[j];

                        results += search(&root, start, last);
                }

        time2 = get_cycles();
        time = time2 - time1;

        time = div_u64(time, search_loops);
        results = div_u64(results, search_loops);
        printk(" -> %llu cycles (%lu results)\n",
               (unsigned long long)time, results);

        for (j = 0; j < nnodes; j++)
                interval_tree_remove(nodes + j, &root);

        return 0;
}

static int intersection_range_check(void)
{
        int i, j, k;
        unsigned long start, last;
        struct interval_tree_node *node;
        unsigned long *intxn1;
        unsigned long *intxn2;

        printk(KERN_ALERT "interval tree iteration\n");

        intxn1 = bitmap_alloc(nnodes, GFP_KERNEL);
        if (!intxn1) {
                WARN_ON_ONCE("Failed to allocate intxn1\n");
                return -ENOMEM;
        }

        intxn2 = bitmap_alloc(nnodes, GFP_KERNEL);
        if (!intxn2) {
                WARN_ON_ONCE("Failed to allocate intxn2\n");
                bitmap_free(intxn1);
                return -ENOMEM;
        }

        for (i = 0; i < search_loops; i++) {
                /* Initialize interval tree for each round */
                init();
                for (j = 0; j < nnodes; j++)
                        interval_tree_insert(nodes + j, &root);

                /* Let's try nsearches different ranges */
                for (k = 0; k < nsearches; k++) {
                        /* Try whole range once */
                        if (!k) {
                                start = 0UL;
                                last = ULONG_MAX;
                        } else {
                                last = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
                                start = (prandom_u32_state(&rnd) >> 4) % last;
                        }

                        /* Walk nodes to mark intersection nodes */
                        bitmap_zero(intxn1, nnodes);
                        for (j = 0; j < nnodes; j++) {
                                node = nodes + j;

                                if (start <= node->last && last >= node->start)
                                        bitmap_set(intxn1, j, 1);
                        }

                        /* Iterate tree to clear intersection nodes */
                        bitmap_zero(intxn2, nnodes);
                        for (node = interval_tree_iter_first(&root, start, last); node;
                             node = interval_tree_iter_next(node, start, last))
                                bitmap_set(intxn2, node - nodes, 1);

                        WARN_ON_ONCE(!bitmap_equal(intxn1, intxn2, nnodes));
                }

                for (j = 0; j < nnodes; j++)
                        interval_tree_remove(nodes + j, &root);
        }

        bitmap_free(intxn1);
        bitmap_free(intxn2);
        return 0;
}

#ifdef CONFIG_INTERVAL_TREE_SPAN_ITER
/*
 * Helper function to get span of current position from maple tree point of
 * view.
 */
static void mas_cur_span(struct ma_state *mas, struct interval_tree_span_iter *state)
{
        unsigned long cur_start;
        unsigned long cur_last;
        int is_hole;

        if (mas->status == ma_overflow)
                return;

        /* walk to current position */
        state->is_hole = mas_walk(mas) ? 0 : 1;

        cur_start = mas->index < state->first_index ?
                        state->first_index : mas->index;

        /* whether we have followers */
        do {

                cur_last = mas->last > state->last_index ?
                                state->last_index : mas->last;

                is_hole = mas_next_range(mas, state->last_index) ? 0 : 1;

        } while (mas->status != ma_overflow && is_hole == state->is_hole);

        if (state->is_hole) {
                state->start_hole = cur_start;
                state->last_hole = cur_last;
        } else {
                state->start_used = cur_start;
                state->last_used = cur_last;
        }

        /* advance position for next round */
        if (mas->status != ma_overflow)
                mas_set(mas, cur_last + 1);
}

static int span_iteration_check(void)
{
        int i, j, k;
        unsigned long start, last;
        struct interval_tree_span_iter span, mas_span;

        DEFINE_MTREE(tree);

        MA_STATE(mas, &tree, 0, 0);

        printk(KERN_ALERT "interval tree span iteration\n");

        for (i = 0; i < search_loops; i++) {
                /* Initialize interval tree for each round */
                init();
                for (j = 0; j < nnodes; j++)
                        interval_tree_insert(nodes + j, &root);

                /* Put all the range into maple tree */
                mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
                mt_set_in_rcu(&tree);

                for (j = 0; j < nnodes; j++)
                        WARN_ON_ONCE(mtree_store_range(&tree, nodes[j].start,
                                        nodes[j].last, nodes + j, GFP_KERNEL));

                /* Let's try nsearches different ranges */
                for (k = 0; k < nsearches; k++) {
                        /* Try whole range once */
                        if (!k) {
                                start = 0UL;
                                last = ULONG_MAX;
                        } else {
                                last = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
                                start = (prandom_u32_state(&rnd) >> 4) % last;
                        }

                        mas_span.first_index = start;
                        mas_span.last_index = last;
                        mas_span.is_hole = -1;
                        mas_set(&mas, start);

                        interval_tree_for_each_span(&span, &root, start, last) {
                                mas_cur_span(&mas, &mas_span);

                                WARN_ON_ONCE(span.is_hole != mas_span.is_hole);

                                if (span.is_hole) {
                                        WARN_ON_ONCE(span.start_hole != mas_span.start_hole);
                                        WARN_ON_ONCE(span.last_hole != mas_span.last_hole);
                                } else {
                                        WARN_ON_ONCE(span.start_used != mas_span.start_used);
                                        WARN_ON_ONCE(span.last_used != mas_span.last_used);
                                }
                        }

                }

                WARN_ON_ONCE(mas.status != ma_overflow);

                /* Cleanup maple tree for each round */
                mtree_destroy(&tree);
                /* Cleanup interval tree for each round */
                for (j = 0; j < nnodes; j++)
                        interval_tree_remove(nodes + j, &root);
        }
        return 0;
}
#else
static inline int span_iteration_check(void) {return 0; }
#endif

static int interval_tree_test_init(void)
{
        nodes = kmalloc_objs(struct interval_tree_node, nnodes);
        if (!nodes)
                return -ENOMEM;

        queries = kmalloc_array(nsearches, sizeof(int), GFP_KERNEL);
        if (!queries) {
                kfree(nodes);
                return -ENOMEM;
        }

        prandom_seed_state(&rnd, seed);

        basic_check();
        search_check();
        intersection_range_check();
        span_iteration_check();

        kfree(queries);
        kfree(nodes);

        return -EAGAIN; /* Fail will directly unload the module */
}

static void interval_tree_test_exit(void)
{
        printk(KERN_ALERT "test exit\n");
}

module_init(interval_tree_test_init)
module_exit(interval_tree_test_exit)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michel Lespinasse");
MODULE_DESCRIPTION("Interval Tree test");