/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
 * Copyright (c) 2023 David Vernet <dvernet@meta.com>
 * Copyright (c) 2023 Tejun Heo <tj@kernel.org>
 */
#include <bpf/bpf.h>
#include <scx/common.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
#include "select_cpu_dfl.bpf.skel.h"
#include "scx_test.h"

#define NUM_CHILDREN 1028

struct select_cpu_dfl_ctx {
        struct select_cpu_dfl   *skel;
        struct bpf_link         *link;
};

static enum scx_test_status setup(void **ctx)
{
        struct select_cpu_dfl_ctx *tctx;

        tctx = malloc(sizeof(*tctx));
        SCX_FAIL_IF(!tctx, "Failed to allocate test context");
        tctx->link = NULL;

        tctx->skel = select_cpu_dfl__open();
        if (!tctx->skel) {
                free(tctx);
                SCX_FAIL("Failed to open");
        }
        SCX_ENUM_INIT(tctx->skel);
        if (select_cpu_dfl__load(tctx->skel)) {
                select_cpu_dfl__destroy(tctx->skel);
                free(tctx);
                SCX_FAIL("Failed to load skel");
        }

        *ctx = tctx;

        return SCX_TEST_PASS;
}

static enum scx_test_status run(void *ctx)
{
        struct select_cpu_dfl_ctx *tctx = ctx;
        pid_t pids[NUM_CHILDREN];
        int i, status, nforked = 0;

        tctx->link = bpf_map__attach_struct_ops(tctx->skel->maps.select_cpu_dfl_ops);
        SCX_FAIL_IF(!tctx->link, "Failed to attach scheduler");

        for (i = 0; i < NUM_CHILDREN; i++) {
                pids[i] = fork();
                if (pids[i] == 0) {
                        sleep(1);
                        exit(0);
                }
                if (pids[i] > 0)
                        nforked++;
        }

        for (i = 0; i < NUM_CHILDREN; i++) {
                if (pids[i] <= 0)
                        continue;
                SCX_EQ(waitpid(pids[i], &status, 0), pids[i]);
                SCX_EQ(status, 0);
        }

        SCX_GT(nforked, 0);
        SCX_ASSERT(!tctx->skel->bss->saw_local);

        return SCX_TEST_PASS;
}

static void cleanup(void *ctx)
{
        struct select_cpu_dfl_ctx *tctx = ctx;

        if (tctx->link)
                bpf_link__destroy(tctx->link);
        select_cpu_dfl__destroy(tctx->skel);
        free(tctx);
}

struct scx_test select_cpu_dfl = {
        .name = "select_cpu_dfl",
        .description = "Verify the default ops.select_cpu() dispatches tasks "
                       "when idles cores are found, and skips ops.enqueue()",
        .setup = setup,
        .run = run,
        .cleanup = cleanup,
};
REGISTER_SCX_TEST(&select_cpu_dfl)