/* SPDX-License-Identifier: GPL-2.0 */
#include <stdbool.h>
#include <linux/limits.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>

#include "kselftest.h"
#include "cgroup_util.h"

#define DEBUG
#ifdef DEBUG
#define debug(args...) fprintf(stderr, args)
#else
#define debug(args...)
#endif

/*
 * Check if the cgroup is frozen by looking at the cgroup.events::frozen value.
 */
static int cg_check_frozen(const char *cgroup, bool frozen)
{
        if (frozen) {
                if (cg_read_strstr(cgroup, "cgroup.events", "frozen 1") != 0) {
                        debug("Cgroup %s isn't frozen\n", cgroup);
                        return -1;
                }
        } else {
                /*
                 * Check the cgroup.events::frozen value.
                 */
                if (cg_read_strstr(cgroup, "cgroup.events", "frozen 0") != 0) {
                        debug("Cgroup %s is frozen\n", cgroup);
                        return -1;
                }
        }

        return 0;
}

/*
 * Freeze the given cgroup.
 */
static int cg_freeze_nowait(const char *cgroup, bool freeze)
{
        return cg_write(cgroup, "cgroup.freeze", freeze ? "1" : "0");
}

/*
 * Attach a task to the given cgroup and wait for a cgroup frozen event.
 * All transient events (e.g. populated) are ignored.
 */
static int cg_enter_and_wait_for_frozen(const char *cgroup, int pid,
                                        bool frozen)
{
        int fd, ret = -1;
        int attempts;

        fd = cg_prepare_for_wait(cgroup);
        if (fd < 0)
                return fd;

        ret = cg_enter(cgroup, pid);
        if (ret)
                goto out;

        for (attempts = 0; attempts < 10; attempts++) {
                ret = cg_wait_for(fd);
                if (ret)
                        break;

                ret = cg_check_frozen(cgroup, frozen);
                if (ret)
                        continue;
        }

out:
        close(fd);
        return ret;
}

/*
 * Freeze the given cgroup and wait for the inotify signal.
 * If there are no events in 10 seconds, treat this as an error.
 * Then check that the cgroup is in the desired state.
 */
static int cg_freeze_wait(const char *cgroup, bool freeze)
{
        int fd, ret = -1;

        fd = cg_prepare_for_wait(cgroup);
        if (fd < 0)
                return fd;

        ret = cg_freeze_nowait(cgroup, freeze);
        if (ret) {
                debug("Error: cg_freeze_nowait() failed\n");
                goto out;
        }

        ret = cg_wait_for(fd);
        if (ret)
                goto out;

        ret = cg_check_frozen(cgroup, freeze);
out:
        close(fd);
        return ret;
}

/*
 * A simple process running in a sleep loop until being
 * re-parented.
 */
static int child_fn(const char *cgroup, void *arg)
{
        int ppid = getppid();

        while (getppid() == ppid)
                usleep(1000);

        return getppid() == ppid;
}

/*
 * A simple test for the cgroup freezer: populated the cgroup with 100
 * running processes and freeze it. Then unfreeze it. Then it kills all
 * processes and destroys the cgroup.
 */
static int test_cgfreezer_simple(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;
        int i;

        cgroup = cg_name(root, "cg_test_simple");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        for (i = 0; i < 100; i++)
                cg_run_nowait(cgroup, child_fn, NULL);

        if (cg_wait_for_proc_count(cgroup, 100))
                goto cleanup;

        if (cg_check_frozen(cgroup, false))
                goto cleanup;

        if (cg_freeze_wait(cgroup, true))
                goto cleanup;

        if (cg_freeze_wait(cgroup, false))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * The test creates the following hierarchy:
 *       A
 *    / / \ \
 *   B  E  I K
 *  /\  |
 * C  D F
 *      |
 *      G
 *      |
 *      H
 *
 * with a process in C, H and 3 processes in K.
 * Then it tries to freeze and unfreeze the whole tree.
 */
static int test_cgfreezer_tree(const char *root)
{
        char *cgroup[10] = {0};
        int ret = KSFT_FAIL;
        int i;

        cgroup[0] = cg_name(root, "cg_test_tree_A");
        if (!cgroup[0])
                goto cleanup;

        cgroup[1] = cg_name(cgroup[0], "B");
        if (!cgroup[1])
                goto cleanup;

        cgroup[2] = cg_name(cgroup[1], "C");
        if (!cgroup[2])
                goto cleanup;

        cgroup[3] = cg_name(cgroup[1], "D");
        if (!cgroup[3])
                goto cleanup;

        cgroup[4] = cg_name(cgroup[0], "E");
        if (!cgroup[4])
                goto cleanup;

        cgroup[5] = cg_name(cgroup[4], "F");
        if (!cgroup[5])
                goto cleanup;

        cgroup[6] = cg_name(cgroup[5], "G");
        if (!cgroup[6])
                goto cleanup;

        cgroup[7] = cg_name(cgroup[6], "H");
        if (!cgroup[7])
                goto cleanup;

        cgroup[8] = cg_name(cgroup[0], "I");
        if (!cgroup[8])
                goto cleanup;

        cgroup[9] = cg_name(cgroup[0], "K");
        if (!cgroup[9])
                goto cleanup;

        for (i = 0; i < 10; i++)
                if (cg_create(cgroup[i]))
                        goto cleanup;

        cg_run_nowait(cgroup[2], child_fn, NULL);
        cg_run_nowait(cgroup[7], child_fn, NULL);
        cg_run_nowait(cgroup[9], child_fn, NULL);
        cg_run_nowait(cgroup[9], child_fn, NULL);
        cg_run_nowait(cgroup[9], child_fn, NULL);

        /*
         * Wait until all child processes will enter
         * corresponding cgroups.
         */

        if (cg_wait_for_proc_count(cgroup[2], 1) ||
            cg_wait_for_proc_count(cgroup[7], 1) ||
            cg_wait_for_proc_count(cgroup[9], 3))
                goto cleanup;

        /*
         * Freeze B.
         */
        if (cg_freeze_wait(cgroup[1], true))
                goto cleanup;

        /*
         * Freeze F.
         */
        if (cg_freeze_wait(cgroup[5], true))
                goto cleanup;

        /*
         * Freeze G.
         */
        if (cg_freeze_wait(cgroup[6], true))
                goto cleanup;

        /*
         * Check that A and E are not frozen.
         */
        if (cg_check_frozen(cgroup[0], false))
                goto cleanup;

        if (cg_check_frozen(cgroup[4], false))
                goto cleanup;

        /*
         * Freeze A. Check that A, B and E are frozen.
         */
        if (cg_freeze_wait(cgroup[0], true))
                goto cleanup;

        if (cg_check_frozen(cgroup[1], true))
                goto cleanup;

        if (cg_check_frozen(cgroup[4], true))
                goto cleanup;

        /*
         * Unfreeze B, F and G
         */
        if (cg_freeze_nowait(cgroup[1], false))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[5], false))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[6], false))
                goto cleanup;

        /*
         * Check that C and H are still frozen.
         */
        if (cg_check_frozen(cgroup[2], true))
                goto cleanup;

        if (cg_check_frozen(cgroup[7], true))
                goto cleanup;

        /*
         * Unfreeze A. Check that A, C and K are not frozen.
         */
        if (cg_freeze_wait(cgroup[0], false))
                goto cleanup;

        if (cg_check_frozen(cgroup[2], false))
                goto cleanup;

        if (cg_check_frozen(cgroup[9], false))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        for (i = 9; i >= 0 && cgroup[i]; i--) {
                cg_destroy(cgroup[i]);
                free(cgroup[i]);
        }

        return ret;
}

/*
 * A fork bomb emulator.
 */
static int forkbomb_fn(const char *cgroup, void *arg)
{
        int ppid;

        fork();
        fork();

        ppid = getppid();

        while (getppid() == ppid)
                usleep(1000);

        return getppid() == ppid;
}

/*
 * The test runs a fork bomb in a cgroup and tries to freeze it.
 * Then it kills all processes and checks that cgroup isn't populated
 * anymore.
 */
static int test_cgfreezer_forkbomb(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;

        cgroup = cg_name(root, "cg_forkbomb_test");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        cg_run_nowait(cgroup, forkbomb_fn, NULL);

        usleep(100000);

        if (cg_freeze_wait(cgroup, true))
                goto cleanup;

        if (cg_killall(cgroup))
                goto cleanup;

        if (cg_wait_for_proc_count(cgroup, 0))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * The test creates a cgroups and freezes it. Then it creates a child cgroup
 * and populates it with a task. After that it checks that the child cgroup
 * is frozen and the parent cgroup remains frozen too.
 */
static int test_cgfreezer_mkdir(const char *root)
{
        int ret = KSFT_FAIL;
        char *parent, *child = NULL;
        int pid;

        parent = cg_name(root, "cg_test_mkdir_A");
        if (!parent)
                goto cleanup;

        child = cg_name(parent, "cg_test_mkdir_B");
        if (!child)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_freeze_wait(parent, true))
                goto cleanup;

        if (cg_create(child))
                goto cleanup;

        pid = cg_run_nowait(child, child_fn, NULL);
        if (pid < 0)
                goto cleanup;

        if (cg_wait_for_proc_count(child, 1))
                goto cleanup;

        if (cg_check_frozen(child, true))
                goto cleanup;

        if (cg_check_frozen(parent, true))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (child)
                cg_destroy(child);
        free(child);
        if (parent)
                cg_destroy(parent);
        free(parent);
        return ret;
}

/*
 * The test creates two nested cgroups, freezes the parent
 * and removes the child. Then it checks that the parent cgroup
 * remains frozen and it's possible to create a new child
 * without unfreezing. The new child is frozen too.
 */
static int test_cgfreezer_rmdir(const char *root)
{
        int ret = KSFT_FAIL;
        char *parent, *child = NULL;

        parent = cg_name(root, "cg_test_rmdir_A");
        if (!parent)
                goto cleanup;

        child = cg_name(parent, "cg_test_rmdir_B");
        if (!child)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_create(child))
                goto cleanup;

        if (cg_freeze_wait(parent, true))
                goto cleanup;

        if (cg_destroy(child))
                goto cleanup;

        if (cg_check_frozen(parent, true))
                goto cleanup;

        if (cg_create(child))
                goto cleanup;

        if (cg_check_frozen(child, true))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (child)
                cg_destroy(child);
        free(child);
        if (parent)
                cg_destroy(parent);
        free(parent);
        return ret;
}

/*
 * The test creates two cgroups: A and B, runs a process in A
 * and performs several migrations:
 * 1) A (running) -> B (frozen)
 * 2) B (frozen) -> A (running)
 * 3) A (frozen) -> B (frozen)
 *
 * On each step it checks the actual state of both cgroups.
 */
static int test_cgfreezer_migrate(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup[2] = {0};
        int pid;

        cgroup[0] = cg_name(root, "cg_test_migrate_A");
        if (!cgroup[0])
                goto cleanup;

        cgroup[1] = cg_name(root, "cg_test_migrate_B");
        if (!cgroup[1])
                goto cleanup;

        if (cg_create(cgroup[0]))
                goto cleanup;

        if (cg_create(cgroup[1]))
                goto cleanup;

        pid = cg_run_nowait(cgroup[0], child_fn, NULL);
        if (pid < 0)
                goto cleanup;

        if (cg_wait_for_proc_count(cgroup[0], 1))
                goto cleanup;

        /*
         * Migrate from A (running) to B (frozen)
         */
        if (cg_freeze_wait(cgroup[1], true))
                goto cleanup;

        if (cg_enter_and_wait_for_frozen(cgroup[1], pid, true))
                goto cleanup;

        if (cg_check_frozen(cgroup[0], false))
                goto cleanup;

        /*
         * Migrate from B (frozen) to A (running)
         */
        if (cg_enter_and_wait_for_frozen(cgroup[0], pid, false))
                goto cleanup;

        if (cg_check_frozen(cgroup[1], true))
                goto cleanup;

        /*
         * Migrate from A (frozen) to B (frozen)
         */
        if (cg_freeze_wait(cgroup[0], true))
                goto cleanup;

        if (cg_enter_and_wait_for_frozen(cgroup[1], pid, true))
                goto cleanup;

        if (cg_check_frozen(cgroup[0], true))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup[0])
                cg_destroy(cgroup[0]);
        free(cgroup[0]);
        if (cgroup[1])
                cg_destroy(cgroup[1]);
        free(cgroup[1]);
        return ret;
}

/*
 * The test checks that ptrace works with a tracing process in a frozen cgroup.
 */
static int test_cgfreezer_ptrace(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;
        siginfo_t siginfo;
        int pid;

        cgroup = cg_name(root, "cg_test_ptrace");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        pid = cg_run_nowait(cgroup, child_fn, NULL);
        if (pid < 0)
                goto cleanup;

        if (cg_wait_for_proc_count(cgroup, 1))
                goto cleanup;

        if (cg_freeze_wait(cgroup, true))
                goto cleanup;

        if (ptrace(PTRACE_SEIZE, pid, NULL, NULL))
                goto cleanup;

        if (ptrace(PTRACE_INTERRUPT, pid, NULL, NULL))
                goto cleanup;

        waitpid(pid, NULL, 0);

        /*
         * Cgroup has to remain frozen, however the test task
         * is in traced state.
         */
        if (cg_check_frozen(cgroup, true))
                goto cleanup;

        if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo))
                goto cleanup;

        if (ptrace(PTRACE_DETACH, pid, NULL, NULL))
                goto cleanup;

        if (cg_check_frozen(cgroup, true))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * Check if the process is stopped.
 */
static int proc_check_stopped(int pid)
{
        char buf[PAGE_SIZE];
        int len;

        len = proc_read_text(pid, 0, "stat", buf, sizeof(buf));
        if (len == -1) {
                debug("Can't get %d stat\n", pid);
                return -1;
        }

        if (strstr(buf, "(test_freezer) T ") == NULL) {
                debug("Process %d in the unexpected state: %s\n", pid, buf);
                return -1;
        }

        return 0;
}

/*
 * Test that it's possible to freeze a cgroup with a stopped process.
 */
static int test_cgfreezer_stopped(const char *root)
{
        int pid, ret = KSFT_FAIL;
        char *cgroup = NULL;

        cgroup = cg_name(root, "cg_test_stopped");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        pid = cg_run_nowait(cgroup, child_fn, NULL);

        if (cg_wait_for_proc_count(cgroup, 1))
                goto cleanup;

        if (kill(pid, SIGSTOP))
                goto cleanup;

        if (cg_check_frozen(cgroup, false))
                goto cleanup;

        if (cg_freeze_wait(cgroup, true))
                goto cleanup;

        if (cg_freeze_wait(cgroup, false))
                goto cleanup;

        if (proc_check_stopped(pid))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * Test that it's possible to freeze a cgroup with a ptraced process.
 */
static int test_cgfreezer_ptraced(const char *root)
{
        int pid, ret = KSFT_FAIL;
        char *cgroup = NULL;
        siginfo_t siginfo;

        cgroup = cg_name(root, "cg_test_ptraced");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        pid = cg_run_nowait(cgroup, child_fn, NULL);

        if (cg_wait_for_proc_count(cgroup, 1))
                goto cleanup;

        if (ptrace(PTRACE_SEIZE, pid, NULL, NULL))
                goto cleanup;

        if (ptrace(PTRACE_INTERRUPT, pid, NULL, NULL))
                goto cleanup;

        waitpid(pid, NULL, 0);

        if (cg_check_frozen(cgroup, false))
                goto cleanup;

        if (cg_freeze_wait(cgroup, true))
                goto cleanup;

        /*
         * cg_check_frozen(cgroup, true) will fail here,
         * because the task is in the TRACEd state.
         */
        if (cg_freeze_wait(cgroup, false))
                goto cleanup;

        if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo))
                goto cleanup;

        if (ptrace(PTRACE_DETACH, pid, NULL, NULL))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

static int vfork_fn(const char *cgroup, void *arg)
{
        int pid = vfork();

        if (pid == 0)
                while (true)
                        sleep(1);

        return pid;
}

/*
 * Test that it's possible to freeze a cgroup with a process,
 * which called vfork() and is waiting for a child.
 */
static int test_cgfreezer_vfork(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;

        cgroup = cg_name(root, "cg_test_vfork");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        cg_run_nowait(cgroup, vfork_fn, NULL);

        if (cg_wait_for_proc_count(cgroup, 2))
                goto cleanup;

        if (cg_freeze_wait(cgroup, true))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * Get the current frozen_usec for the cgroup.
 */
static long cg_check_freezetime(const char *cgroup)
{
        return cg_read_key_long(cgroup, "cgroup.stat.local",
                                "frozen_usec ");
}

/*
 * Test that the freeze time will behave as expected for an empty cgroup.
 */
static int test_cgfreezer_time_empty(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;
        long prev, curr;

        cgroup = cg_name(root, "cg_time_test_empty");
        if (!cgroup)
                goto cleanup;

        /*
         * 1) Create an empty cgroup and check that its freeze time
         *    is 0.
         */
        if (cg_create(cgroup))
                goto cleanup;

        curr = cg_check_freezetime(cgroup);
        if (curr < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }
        if (curr > 0) {
                debug("Expect time (%ld) to be 0\n", curr);
                goto cleanup;
        }

        if (cg_freeze_nowait(cgroup, true))
                goto cleanup;

        /*
         * 2) Sleep for 1000 us. Check that the freeze time is at
         *    least 1000 us.
         */
        usleep(1000);
        curr = cg_check_freezetime(cgroup);
        if (curr < 1000) {
                debug("Expect time (%ld) to be at least 1000 us\n",
                      curr);
                goto cleanup;
        }

        /*
         * 3) Unfreeze the cgroup. Check that the freeze time is
         *    larger than at 2).
         */
        if (cg_freeze_nowait(cgroup, false))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        /*
         * 4) Check the freeze time again to ensure that it has not
         *    changed.
         */
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr != prev) {
                debug("Expect time (%ld) to be unchanged from previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * A simple test for cgroup freezer time accounting. This test follows
 * the same flow as test_cgfreezer_time_empty, but with a single process
 * in the cgroup.
 */
static int test_cgfreezer_time_simple(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;
        long prev, curr;

        cgroup = cg_name(root, "cg_time_test_simple");
        if (!cgroup)
                goto cleanup;

        /*
         * 1) Create a cgroup and check that its freeze time is 0.
         */
        if (cg_create(cgroup))
                goto cleanup;

        curr = cg_check_freezetime(cgroup);
        if (curr < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }
        if (curr > 0) {
                debug("Expect time (%ld) to be 0\n", curr);
                goto cleanup;
        }

        /*
         * 2) Populate the cgroup with one child and check that the
         *    freeze time is still 0.
         */
        cg_run_nowait(cgroup, child_fn, NULL);
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr > prev) {
                debug("Expect time (%ld) to be 0\n", curr);
                goto cleanup;
        }

        if (cg_freeze_nowait(cgroup, true))
                goto cleanup;

        /*
         * 3) Sleep for 1000 us. Check that the freeze time is at
         *    least 1000 us.
         */
        usleep(1000);
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr < 1000) {
                debug("Expect time (%ld) to be at least 1000 us\n",
                      curr);
                goto cleanup;
        }

        /*
         * 4) Unfreeze the cgroup. Check that the freeze time is
         *    larger than at 3).
         */
        if (cg_freeze_nowait(cgroup, false))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        /*
         * 5) Sleep for 1000 us. Check that the freeze time is the
         *    same as at 4).
         */
        usleep(1000);
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr != prev) {
                debug("Expect time (%ld) to be unchanged from previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * Test that freezer time accounting works as expected, even while we're
 * populating a cgroup with processes.
 */
static int test_cgfreezer_time_populate(const char *root)
{
        int ret = KSFT_FAIL;
        char *cgroup = NULL;
        long prev, curr;
        int i;

        cgroup = cg_name(root, "cg_time_test_populate");
        if (!cgroup)
                goto cleanup;

        if (cg_create(cgroup))
                goto cleanup;

        curr = cg_check_freezetime(cgroup);
        if (curr < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }
        if (curr > 0) {
                debug("Expect time (%ld) to be 0\n", curr);
                goto cleanup;
        }

        /*
         * 1) Populate the cgroup with 100 processes. Check that
         *    the freeze time is 0.
         */
        for (i = 0; i < 100; i++)
                cg_run_nowait(cgroup, child_fn, NULL);
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr != prev) {
                debug("Expect time (%ld) to be 0\n", curr);
                goto cleanup;
        }

        /*
         * 2) Wait for the group to become fully populated. Check
         *    that the freeze time is 0.
         */
        if (cg_wait_for_proc_count(cgroup, 100))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr != prev) {
                debug("Expect time (%ld) to be 0\n", curr);
                goto cleanup;
        }

        /*
         * 3) Freeze the cgroup and then populate it with 100 more
         *    processes. Check that the freeze time continues to grow.
         */
        if (cg_freeze_nowait(cgroup, true))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        for (i = 0; i < 100; i++)
                cg_run_nowait(cgroup, child_fn, NULL);
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        /*
         * 4) Wait for the group to become fully populated. Check
         *    that the freeze time is larger than at 3).
         */
        if (cg_wait_for_proc_count(cgroup, 200))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        /*
         * 5) Unfreeze the cgroup. Check that the freeze time is
         *    larger than at 4).
         */
        if (cg_freeze_nowait(cgroup, false))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        /*
         * 6) Kill the processes. Check that the freeze time is the
         *    same as it was at 5).
         */
        if (cg_killall(cgroup))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr != prev) {
                debug("Expect time (%ld) to be unchanged from previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        /*
         * 7) Freeze and unfreeze the cgroup. Check that the freeze
         *    time is larger than it was at 6).
         */
        if (cg_freeze_nowait(cgroup, true))
                goto cleanup;
        if (cg_freeze_nowait(cgroup, false))
                goto cleanup;
        prev = curr;
        curr = cg_check_freezetime(cgroup);
        if (curr <= prev) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr, prev);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        if (cgroup)
                cg_destroy(cgroup);
        free(cgroup);
        return ret;
}

/*
 * Test that frozen time for a cgroup continues to work as expected,
 * even as processes are migrated. Frozen cgroup A's freeze time should
 * continue to increase and running cgroup B's should stay 0.
 */
static int test_cgfreezer_time_migrate(const char *root)
{
        long prev_A, curr_A, curr_B;
        char *cgroup[2] = {0};
        int ret = KSFT_FAIL;
        int pid;

        cgroup[0] = cg_name(root, "cg_time_test_migrate_A");
        if (!cgroup[0])
                goto cleanup;

        cgroup[1] = cg_name(root, "cg_time_test_migrate_B");
        if (!cgroup[1])
                goto cleanup;

        if (cg_create(cgroup[0]))
                goto cleanup;

        if (cg_check_freezetime(cgroup[0]) < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }

        if (cg_create(cgroup[1]))
                goto cleanup;

        pid = cg_run_nowait(cgroup[0], child_fn, NULL);
        if (pid < 0)
                goto cleanup;

        if (cg_wait_for_proc_count(cgroup[0], 1))
                goto cleanup;

        curr_A = cg_check_freezetime(cgroup[0]);
        if (curr_A) {
                debug("Expect time (%ld) to be 0\n", curr_A);
                goto cleanup;
        }
        curr_B = cg_check_freezetime(cgroup[1]);
        if (curr_B) {
                debug("Expect time (%ld) to be 0\n", curr_B);
                goto cleanup;
        }

        /*
         * Freeze cgroup A.
         */
        if (cg_freeze_wait(cgroup[0], true))
                goto cleanup;
        prev_A = curr_A;
        curr_A = cg_check_freezetime(cgroup[0]);
        if (curr_A <= prev_A) {
                debug("Expect time (%ld) to be > 0\n", curr_A);
                goto cleanup;
        }

        /*
         * Migrate from A (frozen) to B (running).
         */
        if (cg_enter(cgroup[1], pid))
                goto cleanup;

        usleep(1000);
        curr_B = cg_check_freezetime(cgroup[1]);
        if (curr_B) {
                debug("Expect time (%ld) to be 0\n", curr_B);
                goto cleanup;
        }

        prev_A = curr_A;
        curr_A = cg_check_freezetime(cgroup[0]);
        if (curr_A <= prev_A) {
                debug("Expect time (%ld) to be more than previous check (%ld)\n",
                      curr_A, prev_A);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        if (cgroup[0])
                cg_destroy(cgroup[0]);
        free(cgroup[0]);
        if (cgroup[1])
                cg_destroy(cgroup[1]);
        free(cgroup[1]);
        return ret;
}

/*
 * The test creates a cgroup and freezes it. Then it creates a child cgroup.
 * After that it checks that the child cgroup has a non-zero freeze time
 * that is less than the parent's. Next, it freezes the child, unfreezes
 * the parent, and sleeps. Finally, it checks that the child's freeze
 * time has grown larger than the parent's.
 */
static int test_cgfreezer_time_parent(const char *root)
{
        char *parent, *child = NULL;
        int ret = KSFT_FAIL;
        long ptime, ctime;

        parent = cg_name(root, "cg_test_parent_A");
        if (!parent)
                goto cleanup;

        child = cg_name(parent, "cg_test_parent_B");
        if (!child)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_check_freezetime(parent) < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }

        if (cg_freeze_wait(parent, true))
                goto cleanup;

        usleep(1000);
        if (cg_create(child))
                goto cleanup;

        if (cg_check_frozen(child, true))
                goto cleanup;

        /*
         * Since the parent was frozen the entire time the child cgroup
         * was being created, we expect the parent's freeze time to be
         * larger than the child's.
         *
         * Ideally, we would be able to check both times simultaneously,
         * but here we get the child's after we get the parent's.
         */
        ptime = cg_check_freezetime(parent);
        ctime = cg_check_freezetime(child);
        if (ptime <= ctime) {
                debug("Expect ptime (%ld) > ctime (%ld)\n", ptime, ctime);
                goto cleanup;
        }

        if (cg_freeze_nowait(child, true))
                goto cleanup;

        if (cg_freeze_wait(parent, false))
                goto cleanup;

        if (cg_check_frozen(child, true))
                goto cleanup;

        usleep(100000);

        ctime = cg_check_freezetime(child);
        ptime = cg_check_freezetime(parent);

        if (ctime <= ptime) {
                debug("Expect ctime (%ld) > ptime (%ld)\n", ctime, ptime);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        if (child)
                cg_destroy(child);
        free(child);
        if (parent)
                cg_destroy(parent);
        free(parent);
        return ret;
}

/*
 * The test creates a parent cgroup and a child cgroup. Then, it freezes
 * the child and checks that the child's freeze time is greater than the
 * parent's, which should be zero.
 */
static int test_cgfreezer_time_child(const char *root)
{
        char *parent, *child = NULL;
        int ret = KSFT_FAIL;
        long ptime, ctime;

        parent = cg_name(root, "cg_test_child_A");
        if (!parent)
                goto cleanup;

        child = cg_name(parent, "cg_test_child_B");
        if (!child)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_check_freezetime(parent) < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }

        if (cg_create(child))
                goto cleanup;

        if (cg_freeze_wait(child, true))
                goto cleanup;

        ctime = cg_check_freezetime(child);
        ptime = cg_check_freezetime(parent);
        if (ptime != 0) {
                debug("Expect ptime (%ld) to be 0\n", ptime);
                goto cleanup;
        }

        if (ctime <= ptime) {
                debug("Expect ctime (%ld) <= ptime (%ld)\n", ctime, ptime);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        if (child)
                cg_destroy(child);
        free(child);
        if (parent)
                cg_destroy(parent);
        free(parent);
        return ret;
}

/*
 * The test creates the following hierarchy:
 *    A
 *    |
 *    B
 *    |
 *    C
 *
 * Then it freezes the cgroups in the order C, B, A.
 * Then it unfreezes the cgroups in the order A, B, C.
 * Then it checks that C's freeze time is larger than B's and
 * that B's is larger than A's.
 */
static int test_cgfreezer_time_nested(const char *root)
{
        char *cgroup[3] = {0};
        int ret = KSFT_FAIL;
        long time[3] = {0};
        int i;

        cgroup[0] = cg_name(root, "cg_test_time_A");
        if (!cgroup[0])
                goto cleanup;

        cgroup[1] = cg_name(cgroup[0], "B");
        if (!cgroup[1])
                goto cleanup;

        cgroup[2] = cg_name(cgroup[1], "C");
        if (!cgroup[2])
                goto cleanup;

        if (cg_create(cgroup[0]))
                goto cleanup;

        if (cg_check_freezetime(cgroup[0]) < 0) {
                ret = KSFT_SKIP;
                goto cleanup;
        }

        if (cg_create(cgroup[1]))
                goto cleanup;

        if (cg_create(cgroup[2]))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[2], true))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[1], true))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[0], true))
                goto cleanup;

        usleep(1000);

        if (cg_freeze_nowait(cgroup[0], false))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[1], false))
                goto cleanup;

        if (cg_freeze_nowait(cgroup[2], false))
                goto cleanup;

        time[2] = cg_check_freezetime(cgroup[2]);
        time[1] = cg_check_freezetime(cgroup[1]);
        time[0] = cg_check_freezetime(cgroup[0]);

        if (time[2] <= time[1]) {
                debug("Expect C's time (%ld) > B's time (%ld)", time[2], time[1]);
                goto cleanup;
        }

        if (time[1] <= time[0]) {
                debug("Expect B's time (%ld) > A's time (%ld)", time[1], time[0]);
                goto cleanup;
        }

        ret = KSFT_PASS;

cleanup:
        for (i = 2; i >= 0 && cgroup[i]; i--) {
                cg_destroy(cgroup[i]);
                free(cgroup[i]);
        }

        return ret;
}

#define T(x) { x, #x }
struct cgfreezer_test {
        int (*fn)(const char *root);
        const char *name;
} tests[] = {
        T(test_cgfreezer_simple),
        T(test_cgfreezer_tree),
        T(test_cgfreezer_forkbomb),
        T(test_cgfreezer_mkdir),
        T(test_cgfreezer_rmdir),
        T(test_cgfreezer_migrate),
        T(test_cgfreezer_ptrace),
        T(test_cgfreezer_stopped),
        T(test_cgfreezer_ptraced),
        T(test_cgfreezer_vfork),
        T(test_cgfreezer_time_empty),
        T(test_cgfreezer_time_simple),
        T(test_cgfreezer_time_populate),
        T(test_cgfreezer_time_migrate),
        T(test_cgfreezer_time_parent),
        T(test_cgfreezer_time_child),
        T(test_cgfreezer_time_nested),
};
#undef T

int main(int argc, char *argv[])
{
        char root[PATH_MAX];
        int i;

        ksft_print_header();
        ksft_set_plan(ARRAY_SIZE(tests));
        if (cg_find_unified_root(root, sizeof(root), NULL))
                ksft_exit_skip("cgroup v2 isn't mounted\n");
        for (i = 0; i < ARRAY_SIZE(tests); i++) {
                switch (tests[i].fn(root)) {
                case KSFT_PASS:
                        ksft_test_result_pass("%s\n", tests[i].name);
                        break;
                case KSFT_SKIP:
                        ksft_test_result_skip("%s\n", tests[i].name);
                        break;
                default:
                        ksft_test_result_fail("%s\n", tests[i].name);
                        break;
                }
        }

        ksft_finished();
}