/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Jeffrey Roberson <jeff@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/libkern.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/kthread.h>
#include <sys/conf.h>
#include <sys/mbuf.h>
#include <sys/smp.h>
#include <sys/smr.h>
#include <sys/stdarg.h>

#include <vm/uma.h>

static uma_zone_t smrs_zone;
static smr_t smrs_smr;

static int smrs_cpus;
static int smrs_writers;
static int smrs_started;
static int smrs_iterations = 10000000;
static int smrs_failures = 0;
static volatile int smrs_completed;

struct smrs {
        int             generation;
        volatile u_int  count;
};

uintptr_t smrs_current;

static void
smrs_error(struct smrs *smrs, const char *fmt, ...)
{
        va_list ap;

        atomic_add_int(&smrs_failures, 1);
        printf("SMR ERROR: wr_seq %d, rd_seq %d, c_seq %d, generation %d, count %d ",
            smrs_smr->c_shared->s_wr.seq, smrs_smr->c_shared->s_rd_seq,
            zpcpu_get(smrs_smr)->c_seq, smrs->generation, smrs->count);
        va_start(ap, fmt);
        (void)vprintf(fmt, ap);
        va_end(ap);
}

static void
smrs_read(void)
{
        struct smrs *cur;
        int cnt;

        /* Wait for the writer to exit. */
        while (smrs_completed == 0) {
                smr_enter(smrs_smr);
                cur = (void *)atomic_load_acq_ptr(&smrs_current);
                if (cur->generation == -1)
                        smrs_error(cur, "read early: Use after free!\n");
                atomic_add_int(&cur->count, 1);
                DELAY(100);
                cnt = atomic_fetchadd_int(&cur->count, -1);
                if (cur->generation == -1)
                        smrs_error(cur, "read late: Use after free!\n");
                else if (cnt <= 0)
                        smrs_error(cur, "Invalid ref\n");
                smr_exit(smrs_smr);
                maybe_yield();
        }
}

static void
smrs_write(void)
{
        struct smrs *cur;
        int i;

        for (i = 0; i < smrs_iterations; i++) {
                cur = uma_zalloc_smr(smrs_zone, M_WAITOK);
                atomic_thread_fence_rel();
                cur = (void *)atomic_swap_ptr(&smrs_current, (uintptr_t)cur);
                uma_zfree_smr(smrs_zone, cur);
        }
}

static void
smrs_thread(void *arg)
{
        int rw = (intptr_t)arg;

        if (rw < smrs_writers)
                smrs_write();
        else
                smrs_read();
        atomic_add_int(&smrs_completed, 1);
        kthread_exit();
}

static void
smrs_start(void)
{
        struct smrs *cur;
        int i;

        smrs_cpus = mp_ncpus;
        if (mp_ncpus > 3)
                smrs_writers = 2;
        else
                smrs_writers = 1;
        smrs_started = smrs_cpus;
        smrs_completed = 0;
        atomic_store_rel_ptr(&smrs_current,
            (uintptr_t)uma_zalloc_smr(smrs_zone, M_WAITOK));
        for (i = 0; i < smrs_started; i++)
                kthread_add((void (*)(void *))smrs_thread,
                    (void *)(intptr_t)i, curproc, NULL, 0, 0, "smrs-%d", i);

        while (smrs_completed != smrs_started)
                pause("prf", hz/2);

        cur = (void *)smrs_current;
        smrs_current = (uintptr_t)NULL;
        uma_zfree_smr(smrs_zone, cur);

        printf("Completed %d loops with %d failures\n",
            smrs_iterations, smrs_failures);
}

static int
smrs_ctor(void *mem, int size, void *arg, int flags)
{
        static int smr_generation = 0;
        struct smrs *smrs = mem;

        if (smrs->generation != -1 && smrs->generation != 0)
                smrs_error(smrs, "ctor: Invalid smr generation on ctor\n");
        else if (smrs->count != 0)
                smrs_error(smrs, "ctor: Invalid count\n");
        smrs->generation = ++smr_generation;

        return (0);
}


static void
smrs_dtor(void *mem, int size, void *arg)
{
        struct smrs *smrs = mem;

        if (smrs->generation == -1)
                smrs_error(smrs, "dtor: Invalid generation");
        smrs->generation = -1;
        if (smrs->count != 0)
                smrs_error(smrs, "dtor: Invalid count\n");
}


static void
smrs_init(void)
{

        smrs_zone = uma_zcreate("smrs", sizeof(struct smrs),
            smrs_ctor,  smrs_dtor, NULL, NULL, UMA_ALIGN_PTR,
            UMA_ZONE_SMR | UMA_ZONE_ZINIT);
        smrs_smr = uma_zone_get_smr(smrs_zone);
}

static void
smrs_fini(void)
{

        uma_zdestroy(smrs_zone);
}

static int
smrs_modevent(module_t mod, int what, void *arg)
{

        switch (what) {
        case MOD_LOAD:
                smrs_init();
                smrs_start();
                break;
        case MOD_UNLOAD:
                smrs_fini();
                break;
        default:
                break;
        }
        return (0);
}

moduledata_t smrs_meta = {
        "smrstress",
        smrs_modevent,
        NULL
};
DECLARE_MODULE(smrstress, smrs_meta, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
MODULE_VERSION(smrstress, 1);