/*-
 * Copyright (c) 2017, 2018 The FreeBSD Foundation
 * All rights reserved.
 * Copyright (c) 2018, 2019 Intel Corporation
 *
 * This software was developed by Konstantin Belousov <kib@FreeBSD.org>
 * under sponsorship from the FreeBSD Foundation.
 *
 * 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/cdefs.h>
#include "opt_acpi.h"
#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/devicestat.h>
#include <sys/disk.h>
#include <sys/efi.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/rwlock.h>
#include <sys/sglist.h>
#include <sys/uio.h>
#include <sys/uuid.h>
#include <geom/geom.h>
#include <geom/geom_int.h>
#include <machine/vmparam.h>
#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <contrib/dev/acpica/include/acpi.h>
#include <contrib/dev/acpica/include/accommon.h>
#include <contrib/dev/acpica/include/acuuid.h>
#include <dev/acpica/acpivar.h>
#include <dev/nvdimm/nvdimm_var.h>

#define UUID_INITIALIZER_VOLATILE_MEMORY \
    {0x7305944f,0xfdda,0x44e3,0xb1,0x6c,{0x3f,0x22,0xd2,0x52,0xe5,0xd0}}
#define UUID_INITIALIZER_PERSISTENT_MEMORY \
    {0x66f0d379,0xb4f3,0x4074,0xac,0x43,{0x0d,0x33,0x18,0xb7,0x8c,0xdb}}
#define UUID_INITIALIZER_CONTROL_REGION \
    {0x92f701f6,0x13b4,0x405d,0x91,0x0b,{0x29,0x93,0x67,0xe8,0x23,0x4c}}
#define UUID_INITIALIZER_DATA_REGION \
    {0x91af0530,0x5d86,0x470e,0xa6,0xb0,{0x0a,0x2d,0xb9,0x40,0x82,0x49}}
#define UUID_INITIALIZER_VOLATILE_VIRTUAL_DISK \
    {0x77ab535a,0x45fc,0x624b,0x55,0x60,{0xf7,0xb2,0x81,0xd1,0xf9,0x6e}}
#define UUID_INITIALIZER_VOLATILE_VIRTUAL_CD \
    {0x3d5abd30,0x4175,0x87ce,0x6d,0x64,{0xd2,0xad,0xe5,0x23,0xc4,0xbb}}
#define UUID_INITIALIZER_PERSISTENT_VIRTUAL_DISK \
    {0x5cea02c9,0x4d07,0x69d3,0x26,0x9f,{0x44,0x96,0xfb,0xe0,0x96,0xf9}}
#define UUID_INITIALIZER_PERSISTENT_VIRTUAL_CD \
    {0x08018188,0x42cd,0xbb48,0x10,0x0f,{0x53,0x87,0xd5,0x3d,0xed,0x3d}}

static struct nvdimm_SPA_uuid_list_elm {
        const char              *u_name;
        struct uuid             u_id;
        const bool              u_usr_acc;
} nvdimm_SPA_uuid_list[] = {
        [SPA_TYPE_VOLATILE_MEMORY] = {
                .u_name =       "VOLA MEM ",
                .u_id =         UUID_INITIALIZER_VOLATILE_MEMORY,
                .u_usr_acc =    true,
        },
        [SPA_TYPE_PERSISTENT_MEMORY] = {
                .u_name =       "PERS MEM",
                .u_id =         UUID_INITIALIZER_PERSISTENT_MEMORY,
                .u_usr_acc =    true,
        },
        [SPA_TYPE_CONTROL_REGION] = {
                .u_name =       "CTRL RG ",
                .u_id =         UUID_INITIALIZER_CONTROL_REGION,
                .u_usr_acc =    false,
        },
        [SPA_TYPE_DATA_REGION] = {
                .u_name =       "DATA RG ",
                .u_id =         UUID_INITIALIZER_DATA_REGION,
                .u_usr_acc =    true,
        },
        [SPA_TYPE_VOLATILE_VIRTUAL_DISK] = {
                .u_name =       "VIRT DSK",
                .u_id =         UUID_INITIALIZER_VOLATILE_VIRTUAL_DISK,
                .u_usr_acc =    true,
        },
        [SPA_TYPE_VOLATILE_VIRTUAL_CD] = {
                .u_name =       "VIRT CD ",
                .u_id =         UUID_INITIALIZER_VOLATILE_VIRTUAL_CD,
                .u_usr_acc =    true,
        },
        [SPA_TYPE_PERSISTENT_VIRTUAL_DISK] = {
                .u_name =       "PV DSK  ",
                .u_id =         UUID_INITIALIZER_PERSISTENT_VIRTUAL_DISK,
                .u_usr_acc =    true,
        },
        [SPA_TYPE_PERSISTENT_VIRTUAL_CD] = {
                .u_name =       "PV CD   ",
                .u_id =         UUID_INITIALIZER_PERSISTENT_VIRTUAL_CD,
                .u_usr_acc =    true,
        },
};

enum SPA_mapping_type
nvdimm_spa_type_from_name(const char *name)
{
        int j;

        for (j = 0; j < nitems(nvdimm_SPA_uuid_list); j++) {
                if (strcmp(name, nvdimm_SPA_uuid_list[j].u_name) != 0)
                        continue;
                return (j);
        }
        return (SPA_TYPE_UNKNOWN);
}

enum SPA_mapping_type
nvdimm_spa_type_from_uuid(struct uuid *uuid)
{
        int j;

        for (j = 0; j < nitems(nvdimm_SPA_uuid_list); j++) {
                if (uuidcmp(uuid, &nvdimm_SPA_uuid_list[j].u_id) != 0)
                        continue;
                return (j);
        }
        return (SPA_TYPE_UNKNOWN);
}

bool
nvdimm_spa_type_user_accessible(enum SPA_mapping_type spa_type)
{

        if ((int)spa_type < 0 || spa_type >= nitems(nvdimm_SPA_uuid_list))
                return (false);
        return (nvdimm_SPA_uuid_list[spa_type].u_usr_acc);
}

static vm_memattr_t
nvdimm_spa_memattr(uint64_t efi_mem_flags)
{
        vm_memattr_t mode;

        if ((efi_mem_flags & EFI_MD_ATTR_WB) != 0)
                mode = VM_MEMATTR_WRITE_BACK;
        else if ((efi_mem_flags & EFI_MD_ATTR_WT) != 0)
                mode = VM_MEMATTR_WRITE_THROUGH;
        else if ((efi_mem_flags & EFI_MD_ATTR_WC) != 0)
                mode = VM_MEMATTR_WRITE_COMBINING;
        else if ((efi_mem_flags & EFI_MD_ATTR_WP) != 0)
                mode = VM_MEMATTR_WRITE_PROTECTED;
        else if ((efi_mem_flags & EFI_MD_ATTR_UC) != 0)
                mode = VM_MEMATTR_UNCACHEABLE;
        else {
                if (bootverbose)
                        printf("SPA mapping attr %#lx unsupported\n",
                            efi_mem_flags);
                mode = VM_MEMATTR_UNCACHEABLE;
        }
        return (mode);
}

static int
nvdimm_spa_uio(struct nvdimm_spa_dev *dev, struct uio *uio)
{
        struct vm_page m, *ma;
        off_t off;
        vm_memattr_t mattr;
        int error, n;

        error = 0;
        if (dev->spa_kva == NULL) {
                mattr = dev->spa_memattr;
                bzero(&m, sizeof(m));
                vm_page_initfake(&m, 0, mattr);
                ma = &m;
                while (uio->uio_resid > 0) {
                        if (uio->uio_offset >= dev->spa_len)
                                break;
                        off = dev->spa_phys_base + uio->uio_offset;
                        vm_page_updatefake(&m, trunc_page(off), mattr);
                        n = PAGE_SIZE;
                        if (n > uio->uio_resid)
                                n = uio->uio_resid;
                        error = uiomove_fromphys(&ma, off & PAGE_MASK, n, uio);
                        if (error != 0)
                                break;
                }
        } else {
                while (uio->uio_resid > 0) {
                        if (uio->uio_offset >= dev->spa_len)
                                break;
                        n = INT_MAX;
                        if (n > uio->uio_resid)
                                n = uio->uio_resid;
                        if (uio->uio_offset + n > dev->spa_len)
                                n = dev->spa_len - uio->uio_offset;
                        error = uiomove((char *)dev->spa_kva + uio->uio_offset,
                            n, uio);
                        if (error != 0)
                                break;
                }
        }
        return (error);
}

static int
nvdimm_spa_rw(struct cdev *dev, struct uio *uio, int ioflag)
{

        return (nvdimm_spa_uio(dev->si_drv1, uio));
}

static int
nvdimm_spa_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag,
    struct thread *td)
{
        struct nvdimm_spa_dev *dev;
        int error;

        dev = cdev->si_drv1;
        error = 0;
        switch (cmd) {
        case DIOCGSECTORSIZE:
                *(u_int *)data = DEV_BSIZE;
                break;
        case DIOCGMEDIASIZE:
                *(off_t *)data = dev->spa_len;
                break;
        default:
                error = ENOTTY;
                break;
        }
        return (error);
}

static int
nvdimm_spa_mmap_single(struct cdev *cdev, vm_ooffset_t *offset, vm_size_t size,
    vm_object_t *objp, int nprot)
{
        struct nvdimm_spa_dev *dev;

        dev = cdev->si_drv1;
        if (dev->spa_obj == NULL)
                return (ENXIO);
        if (*offset >= dev->spa_len || *offset + size < *offset ||
            *offset + size > dev->spa_len)
                return (EINVAL);
        vm_object_reference(dev->spa_obj);
        *objp = dev->spa_obj;
        return (0);
}

static struct cdevsw spa_cdevsw = {
        .d_version =    D_VERSION,
        .d_flags =      D_DISK,
        .d_name =       "nvdimm_spa",
        .d_read =       nvdimm_spa_rw,
        .d_write =      nvdimm_spa_rw,
        .d_ioctl =      nvdimm_spa_ioctl,
        .d_mmap_single = nvdimm_spa_mmap_single,
};

static void
nvdimm_spa_g_all_unmapped(struct nvdimm_spa_dev *dev, struct bio *bp, int rw)
{
        struct vm_page maa[bp->bio_ma_n];
        vm_page_t ma[bp->bio_ma_n];
        vm_memattr_t mattr;
        int i;

        mattr = dev->spa_memattr;
        for (i = 0; i < nitems(ma); i++) {
                bzero(&maa[i], sizeof(maa[i]));
                vm_page_initfake(&maa[i], dev->spa_phys_base +
                    trunc_page(bp->bio_offset) + PAGE_SIZE * i, mattr);
                ma[i] = &maa[i];
        }
        if (rw == BIO_READ)
                pmap_copy_pages(ma, bp->bio_offset & PAGE_MASK, bp->bio_ma,
                    bp->bio_ma_offset, bp->bio_length);
        else
                pmap_copy_pages(bp->bio_ma, bp->bio_ma_offset, ma,
                    bp->bio_offset & PAGE_MASK, bp->bio_length);
}

static void
nvdimm_spa_g_thread(void *arg)
{
        struct g_spa *sc;
        struct bio *bp;
        struct uio auio;
        struct iovec aiovec;
        int error;

        sc = arg;
        for (;;) {
                mtx_lock(&sc->spa_g_mtx);
                for (;;) {
                        bp = bioq_takefirst(&sc->spa_g_queue);
                        if (bp != NULL)
                                break;
                        msleep(&sc->spa_g_queue, &sc->spa_g_mtx, PRIBIO,
                            "spa_g", 0);
                        if (!sc->spa_g_proc_run) {
                                sc->spa_g_proc_exiting = true;
                                wakeup(&sc->spa_g_queue);
                                mtx_unlock(&sc->spa_g_mtx);
                                kproc_exit(0);
                        }
                        continue;
                }
                mtx_unlock(&sc->spa_g_mtx);
                if (bp->bio_cmd != BIO_READ && bp->bio_cmd != BIO_WRITE &&
                    bp->bio_cmd != BIO_FLUSH) {
                        error = EOPNOTSUPP;
                        goto completed;
                }

                error = 0;
                if (bp->bio_cmd == BIO_FLUSH) {
                        if (sc->dev->spa_kva != NULL) {
                                pmap_large_map_wb(sc->dev->spa_kva,
                                    sc->dev->spa_len);
                        } else {
                                pmap_flush_cache_phys_range(
                                    (vm_paddr_t)sc->dev->spa_phys_base,
                                    (vm_paddr_t)sc->dev->spa_phys_base +
                                    sc->dev->spa_len, sc->dev->spa_memattr);
                        }
                        /*
                         * XXX flush IMC
                         */
                        goto completed;
                }
                
                if ((bp->bio_flags & BIO_UNMAPPED) != 0) {
                        if (sc->dev->spa_kva != NULL) {
                                aiovec.iov_base = (char *)sc->dev->spa_kva +
                                    bp->bio_offset;
                                aiovec.iov_len = bp->bio_length;
                                auio.uio_iov = &aiovec;
                                auio.uio_iovcnt = 1;
                                auio.uio_resid = bp->bio_length;
                                auio.uio_offset = bp->bio_offset;
                                auio.uio_segflg = UIO_SYSSPACE;
                                auio.uio_rw = bp->bio_cmd == BIO_READ ?
                                    UIO_WRITE : UIO_READ;
                                auio.uio_td = curthread;
                                error = uiomove_fromphys(bp->bio_ma,
                                    bp->bio_ma_offset, bp->bio_length, &auio);
                                bp->bio_resid = auio.uio_resid;
                        } else {
                                nvdimm_spa_g_all_unmapped(sc->dev, bp,
                                    bp->bio_cmd);
                                bp->bio_resid = bp->bio_length;
                                error = 0;
                        }
                } else {
                        aiovec.iov_base = bp->bio_data;
                        aiovec.iov_len = bp->bio_length;
                        auio.uio_iov = &aiovec;
                        auio.uio_iovcnt = 1;
                        auio.uio_resid = bp->bio_length;
                        auio.uio_offset = bp->bio_offset;
                        auio.uio_segflg = UIO_SYSSPACE;
                        auio.uio_rw = bp->bio_cmd == BIO_READ ? UIO_READ :
                            UIO_WRITE;
                        auio.uio_td = curthread;
                        error = nvdimm_spa_uio(sc->dev, &auio);
                        bp->bio_resid = auio.uio_resid;
                }
                bp->bio_bcount = bp->bio_length;
                devstat_end_transaction_bio(sc->spa_g_devstat, bp);
completed:
                bp->bio_completed = bp->bio_length;
                g_io_deliver(bp, error);
        }
}

static void
nvdimm_spa_g_start(struct bio *bp)
{
        struct g_spa *sc;

        sc = bp->bio_to->geom->softc;
        if (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE) {
                devstat_start_transaction_bio(sc->spa_g_devstat, bp);
        }
        mtx_lock(&sc->spa_g_mtx);
        bioq_disksort(&sc->spa_g_queue, bp);
        wakeup(&sc->spa_g_queue);
        mtx_unlock(&sc->spa_g_mtx);
}

static int
nvdimm_spa_g_access(struct g_provider *pp, int r, int w, int e)
{

        return (0);
}

static struct g_geom * nvdimm_spa_g_create(struct nvdimm_spa_dev *dev,
    const char *name);
static g_ctl_destroy_geom_t nvdimm_spa_g_destroy_geom;

struct g_class nvdimm_spa_g_class = {
        .name =         "SPA",
        .version =      G_VERSION,
        .start =        nvdimm_spa_g_start,
        .access =       nvdimm_spa_g_access,
        .destroy_geom = nvdimm_spa_g_destroy_geom,
};
DECLARE_GEOM_CLASS(nvdimm_spa_g_class, g_spa);

int
nvdimm_spa_init(struct SPA_mapping *spa, ACPI_NFIT_SYSTEM_ADDRESS *nfitaddr,
    enum SPA_mapping_type spa_type)
{
        char *name;
        int error;

        spa->spa_type = spa_type;
        spa->spa_nfit_idx = nfitaddr->RangeIndex;
        spa->dev.spa_domain =
            ((nfitaddr->Flags & ACPI_NFIT_PROXIMITY_VALID) != 0) ?
            nfitaddr->ProximityDomain : -1;
        spa->dev.spa_phys_base = nfitaddr->Address;
        spa->dev.spa_len = nfitaddr->Length;
        spa->dev.spa_efi_mem_flags = nfitaddr->MemoryMapping;
        if (bootverbose) {
                printf("NVDIMM SPA%d base %#016jx len %#016jx %s fl %#jx\n",
                    spa->spa_nfit_idx,
                    (uintmax_t)spa->dev.spa_phys_base,
                    (uintmax_t)spa->dev.spa_len,
                    nvdimm_SPA_uuid_list[spa_type].u_name,
                    spa->dev.spa_efi_mem_flags);
        }
        spa->dev.spa_memattr = nvdimm_spa_memattr(nfitaddr->MemoryMapping);
        if (!nvdimm_SPA_uuid_list[spa_type].u_usr_acc)
                return (0);

        asprintf(&name, M_NVDIMM, "spa%d", spa->spa_nfit_idx);
        error = nvdimm_spa_dev_init(&spa->dev, name, spa->spa_nfit_idx);
        free(name, M_NVDIMM);
        return (error);
}

int
nvdimm_spa_dev_init(struct nvdimm_spa_dev *dev, const char *name, int unit)
{
        struct make_dev_args mda;
        struct sglist *spa_sg;
        char *devname;
        int error, error1;

        error1 = pmap_large_map(dev->spa_phys_base, dev->spa_len,
            &dev->spa_kva, dev->spa_memattr);
        if (error1 != 0) {
                printf("NVDIMM %s cannot map into KVA, error %d\n", name,
                    error1);
                dev->spa_kva = NULL;
        }

        spa_sg = sglist_alloc(1, M_WAITOK);
        error = sglist_append_phys(spa_sg, dev->spa_phys_base,
            dev->spa_len);
        if (error == 0) {
                dev->spa_obj = vm_pager_allocate(OBJT_SG, spa_sg, dev->spa_len,
                    VM_PROT_ALL, 0, NULL);
                if (dev->spa_obj == NULL) {
                        printf("NVDIMM %s failed to alloc vm object", name);
                        sglist_free(spa_sg);
                }
        } else {
                printf("NVDIMM %s failed to init sglist, error %d", name,
                    error);
                sglist_free(spa_sg);
        }

        make_dev_args_init(&mda);
        mda.mda_flags = MAKEDEV_WAITOK | MAKEDEV_CHECKNAME;
        mda.mda_devsw = &spa_cdevsw;
        mda.mda_cr = NULL;
        mda.mda_uid = UID_ROOT;
        mda.mda_gid = GID_OPERATOR;
        mda.mda_mode = 0660;
        mda.mda_si_drv1 = dev;
        mda.mda_unit = unit;
        asprintf(&devname, M_NVDIMM, "nvdimm_%s", name);
        error = make_dev_s(&mda, &dev->spa_dev, "%s", devname);
        free(devname, M_NVDIMM);
        if (error != 0) {
                printf("NVDIMM %s cannot create devfs node, error %d\n", name,
                    error);
                if (error1 == 0)
                        error1 = error;
        }
        dev->spa_g = nvdimm_spa_g_create(dev, name);
        if (dev->spa_g == NULL && error1 == 0)
                error1 = ENXIO;
        return (error1);
}

static struct g_geom *
nvdimm_spa_g_create(struct nvdimm_spa_dev *dev, const char *name)
{
        struct g_geom *gp;
        struct g_spa *sc;
        int error;

        gp = NULL;
        sc = malloc(sizeof(struct g_spa), M_NVDIMM, M_WAITOK | M_ZERO);
        sc->dev = dev;
        bioq_init(&sc->spa_g_queue);
        mtx_init(&sc->spa_g_mtx, "spag", NULL, MTX_DEF);
        sc->spa_g_proc_run = true;
        sc->spa_g_proc_exiting = false;
        error = kproc_create(nvdimm_spa_g_thread, sc, &sc->spa_g_proc, 0, 0,
            "g_spa");
        if (error != 0) {
                mtx_destroy(&sc->spa_g_mtx);
                free(sc, M_NVDIMM);
                printf("NVDIMM %s cannot create geom worker, error %d\n", name,
                    error);
        } else {
                g_topology_lock();
                gp = g_new_geomf(&nvdimm_spa_g_class, "%s", name);
                gp->softc = sc;
                sc->spa_p = g_new_providerf(gp, "%s", name);
                sc->spa_p->mediasize = dev->spa_len;
                sc->spa_p->sectorsize = DEV_BSIZE;
                sc->spa_p->flags |= G_PF_DIRECT_SEND | G_PF_DIRECT_RECEIVE |
                    G_PF_ACCEPT_UNMAPPED;
                g_error_provider(sc->spa_p, 0);
                sc->spa_g_devstat = devstat_new_entry("spa", -1, DEV_BSIZE,
                    DEVSTAT_ALL_SUPPORTED, DEVSTAT_TYPE_DIRECT,
                    DEVSTAT_PRIORITY_MAX);
                g_topology_unlock();
        }
        return (gp);
}

void
nvdimm_spa_fini(struct SPA_mapping *spa)
{

        nvdimm_spa_dev_fini(&spa->dev);
}

void
nvdimm_spa_dev_fini(struct nvdimm_spa_dev *dev)
{

        if (dev->spa_g != NULL) {
                g_topology_lock();
                nvdimm_spa_g_destroy_geom(NULL, dev->spa_g->class, dev->spa_g);
                g_topology_unlock();
        }
        if (dev->spa_dev != NULL) {
                destroy_dev(dev->spa_dev);
                dev->spa_dev = NULL;
        }
        vm_object_deallocate(dev->spa_obj);
        if (dev->spa_kva != NULL) {
                pmap_large_unmap(dev->spa_kva, dev->spa_len);
                dev->spa_kva = NULL;
        }
}

static int
nvdimm_spa_g_destroy_geom(struct gctl_req *req, struct g_class *cp,
    struct g_geom *gp)
{
        struct g_spa *sc;

        sc = gp->softc;
        mtx_lock(&sc->spa_g_mtx);
        sc->spa_g_proc_run = false;
        wakeup(&sc->spa_g_queue);
        while (!sc->spa_g_proc_exiting)
                msleep(&sc->spa_g_queue, &sc->spa_g_mtx, PRIBIO, "spa_e", 0);
        mtx_unlock(&sc->spa_g_mtx);
        g_topology_assert();
        g_wither_geom(gp, ENXIO);
        sc->spa_p = NULL;
        if (sc->spa_g_devstat != NULL) {
                devstat_remove_entry(sc->spa_g_devstat);
                sc->spa_g_devstat = NULL;
        }
        mtx_destroy(&sc->spa_g_mtx);
        free(sc, M_NVDIMM);
        return (0);
}