/* Copyright (c) 2013 Coraid, Inc.  See COPYING for GPL terms. */
/*
 * aoecmd.c
 * Filesystem request handling methods
 */

#include <linux/ata.h>
#include <linux/slab.h>
#include <linux/hdreg.h>
#include <linux/blk-mq.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/moduleparam.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <net/net_namespace.h>
#include <linux/unaligned.h>
#include <linux/uio.h>
#include "aoe.h"

#define MAXIOC (8192)   /* default meant to avoid most soft lockups */

static void ktcomplete(struct frame *, struct sk_buff *);
static int count_targets(struct aoedev *d, int *untainted);

static struct buf *nextbuf(struct aoedev *);

static int aoe_deadsecs = 60 * 3;
module_param(aoe_deadsecs, int, 0644);
MODULE_PARM_DESC(aoe_deadsecs, "After aoe_deadsecs seconds, give up and fail dev.");

static int aoe_maxout = 64;
module_param(aoe_maxout, int, 0644);
MODULE_PARM_DESC(aoe_maxout,
        "Only aoe_maxout outstanding packets for every MAC on eX.Y.");

/* The number of online cpus during module initialization gives us a
 * convenient heuristic cap on the parallelism used for ktio threads
 * doing I/O completion.  It is not important that the cap equal the
 * actual number of running CPUs at any given time, but because of CPU
 * hotplug, we take care to use ncpus instead of using
 * num_online_cpus() after module initialization.
 */
static int ncpus;

/* mutex lock used for synchronization while thread spawning */
static DEFINE_MUTEX(ktio_spawn_lock);

static wait_queue_head_t *ktiowq;
static struct ktstate *kts;

/* io completion queue */
struct iocq_ktio {
        struct list_head head;
        spinlock_t lock;
};
static struct iocq_ktio *iocq;

static struct page *empty_page;

static struct sk_buff *
new_skb(ulong len)
{
        struct sk_buff *skb;

        skb = alloc_skb(len + MAX_HEADER, GFP_ATOMIC);
        if (skb) {
                skb_reserve(skb, MAX_HEADER);
                skb_reset_mac_header(skb);
                skb_reset_network_header(skb);
                skb->protocol = __constant_htons(ETH_P_AOE);
                skb_checksum_none_assert(skb);
        }
        return skb;
}

static struct frame *
getframe_deferred(struct aoedev *d, u32 tag)
{
        struct list_head *head, *pos, *nx;
        struct frame *f;

        head = &d->rexmitq;
        list_for_each_safe(pos, nx, head) {
                f = list_entry(pos, struct frame, head);
                if (f->tag == tag) {
                        list_del(pos);
                        return f;
                }
        }
        return NULL;
}

static struct frame *
getframe(struct aoedev *d, u32 tag)
{
        struct frame *f;
        struct list_head *head, *pos, *nx;
        u32 n;

        n = tag % NFACTIVE;
        head = &d->factive[n];
        list_for_each_safe(pos, nx, head) {
                f = list_entry(pos, struct frame, head);
                if (f->tag == tag) {
                        list_del(pos);
                        return f;
                }
        }
        return NULL;
}

/*
 * Leave the top bit clear so we have tagspace for userland.
 * The bottom 16 bits are the xmit tick for rexmit/rttavg processing.
 * This driver reserves tag -1 to mean "unused frame."
 */
static int
newtag(struct aoedev *d)
{
        register ulong n;

        n = jiffies & 0xffff;
        return n | (++d->lasttag & 0x7fff) << 16;
}

static u32
aoehdr_atainit(struct aoedev *d, struct aoetgt *t, struct aoe_hdr *h)
{
        u32 host_tag = newtag(d);

        memcpy(h->src, t->ifp->nd->dev_addr, sizeof h->src);
        memcpy(h->dst, t->addr, sizeof h->dst);
        h->type = __constant_cpu_to_be16(ETH_P_AOE);
        h->verfl = AOE_HVER;
        h->major = cpu_to_be16(d->aoemajor);
        h->minor = d->aoeminor;
        h->cmd = AOECMD_ATA;
        h->tag = cpu_to_be32(host_tag);

        return host_tag;
}

static inline void
put_lba(struct aoe_atahdr *ah, sector_t lba)
{
        ah->lba0 = lba;
        ah->lba1 = lba >>= 8;
        ah->lba2 = lba >>= 8;
        ah->lba3 = lba >>= 8;
        ah->lba4 = lba >>= 8;
        ah->lba5 = lba >>= 8;
}

static struct aoeif *
ifrotate(struct aoetgt *t)
{
        struct aoeif *ifp;

        ifp = t->ifp;
        ifp++;
        if (ifp >= &t->ifs[NAOEIFS] || ifp->nd == NULL)
                ifp = t->ifs;
        if (ifp->nd == NULL)
                return NULL;
        return t->ifp = ifp;
}

static void
skb_pool_put(struct aoedev *d, struct sk_buff *skb)
{
        __skb_queue_tail(&d->skbpool, skb);
}

static struct sk_buff *
skb_pool_get(struct aoedev *d)
{
        struct sk_buff *skb = skb_peek(&d->skbpool);

        if (skb && atomic_read(&skb_shinfo(skb)->dataref) == 1) {
                __skb_unlink(skb, &d->skbpool);
                return skb;
        }
        if (skb_queue_len(&d->skbpool) < NSKBPOOLMAX &&
            (skb = new_skb(ETH_ZLEN)))
                return skb;

        return NULL;
}

void
aoe_freetframe(struct frame *f)
{
        struct aoetgt *t;

        t = f->t;
        f->buf = NULL;
        memset(&f->iter, 0, sizeof(f->iter));
        f->r_skb = NULL;
        f->flags = 0;
        list_add(&f->head, &t->ffree);
}

static struct frame *
newtframe(struct aoedev *d, struct aoetgt *t)
{
        struct frame *f;
        struct sk_buff *skb;
        struct list_head *pos;

        if (list_empty(&t->ffree)) {
                if (t->falloc >= NSKBPOOLMAX*2)
                        return NULL;
                f = kzalloc_objs(*f, 1, GFP_ATOMIC);
                if (f == NULL)
                        return NULL;
                t->falloc++;
                f->t = t;
        } else {
                pos = t->ffree.next;
                list_del(pos);
                f = list_entry(pos, struct frame, head);
        }

        skb = f->skb;
        if (skb == NULL) {
                f->skb = skb = new_skb(ETH_ZLEN);
                if (!skb) {
bail:                   aoe_freetframe(f);
                        return NULL;
                }
        }

        if (atomic_read(&skb_shinfo(skb)->dataref) != 1) {
                skb = skb_pool_get(d);
                if (skb == NULL)
                        goto bail;
                skb_pool_put(d, f->skb);
                f->skb = skb;
        }

        skb->truesize -= skb->data_len;
        skb_shinfo(skb)->nr_frags = skb->data_len = 0;
        skb_trim(skb, 0);
        return f;
}

static struct frame *
newframe(struct aoedev *d)
{
        struct frame *f;
        struct aoetgt *t, **tt;
        int totout = 0;
        int use_tainted;
        int has_untainted;

        if (!d->targets || !d->targets[0]) {
                printk(KERN_ERR "aoe: NULL TARGETS!\n");
                return NULL;
        }
        tt = d->tgt;    /* last used target */
        for (use_tainted = 0, has_untainted = 0;;) {
                tt++;
                if (tt >= &d->targets[d->ntargets] || !*tt)
                        tt = d->targets;
                t = *tt;
                if (!t->taint) {
                        has_untainted = 1;
                        totout += t->nout;
                }
                if (t->nout < t->maxout
                && (use_tainted || !t->taint)
                && t->ifp->nd) {
                        f = newtframe(d, t);
                        if (f) {
                                ifrotate(t);
                                d->tgt = tt;
                                return f;
                        }
                }
                if (tt == d->tgt) {     /* we've looped and found nada */
                        if (!use_tainted && !has_untainted)
                                use_tainted = 1;
                        else
                                break;
                }
        }
        if (totout == 0) {
                d->kicked++;
                d->flags |= DEVFL_KICKME;
        }
        return NULL;
}

static void
skb_fillup(struct sk_buff *skb, struct bio *bio, struct bvec_iter iter)
{
        int frag = 0;
        struct bio_vec bv;

        __bio_for_each_segment(bv, bio, iter, iter)
                skb_fill_page_desc(skb, frag++, bv.bv_page,
                                   bv.bv_offset, bv.bv_len);
}

static void
fhash(struct frame *f)
{
        struct aoedev *d = f->t->d;
        u32 n;

        n = f->tag % NFACTIVE;
        list_add_tail(&f->head, &d->factive[n]);
}

static void
ata_rw_frameinit(struct frame *f)
{
        struct aoetgt *t;
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct sk_buff *skb;
        char writebit, extbit;

        skb = f->skb;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ah = (struct aoe_atahdr *) (h + 1);
        skb_put(skb, sizeof(*h) + sizeof(*ah));
        memset(h, 0, skb->len);

        writebit = 0x10;
        extbit = 0x4;

        t = f->t;
        f->tag = aoehdr_atainit(t->d, t, h);
        fhash(f);
        t->nout++;
        f->waited = 0;
        f->waited_total = 0;

        /* set up ata header */
        ah->scnt = f->iter.bi_size >> 9;
        put_lba(ah, f->iter.bi_sector);
        if (t->d->flags & DEVFL_EXT) {
                ah->aflags |= AOEAFL_EXT;
        } else {
                extbit = 0;
                ah->lba3 &= 0x0f;
                ah->lba3 |= 0xe0;       /* LBA bit + obsolete 0xa0 */
        }
        if (f->buf && bio_data_dir(f->buf->bio) == WRITE) {
                skb_fillup(skb, f->buf->bio, f->iter);
                ah->aflags |= AOEAFL_WRITE;
                skb->len += f->iter.bi_size;
                skb->data_len = f->iter.bi_size;
                skb->truesize += f->iter.bi_size;
                t->wpkts++;
        } else {
                t->rpkts++;
                writebit = 0;
        }

        ah->cmdstat = ATA_CMD_PIO_READ | writebit | extbit;
        dev_hold(t->ifp->nd);
        skb->dev = t->ifp->nd;
}

static int
aoecmd_ata_rw(struct aoedev *d)
{
        struct frame *f;
        struct buf *buf;
        struct sk_buff *skb;
        struct sk_buff_head queue;

        buf = nextbuf(d);
        if (buf == NULL)
                return 0;
        f = newframe(d);
        if (f == NULL)
                return 0;

        /* initialize the headers & frame */
        f->buf = buf;
        f->iter = buf->iter;
        f->iter.bi_size = min_t(unsigned long,
                                d->maxbcnt ?: DEFAULTBCNT,
                                f->iter.bi_size);
        bio_advance_iter(buf->bio, &buf->iter, f->iter.bi_size);

        if (!buf->iter.bi_size)
                d->ip.buf = NULL;

        /* mark all tracking fields and load out */
        buf->nframesout += 1;

        ata_rw_frameinit(f);

        skb = skb_clone(f->skb, GFP_ATOMIC);
        if (skb) {
                f->sent = ktime_get();
                __skb_queue_head_init(&queue);
                __skb_queue_tail(&queue, skb);
                aoenet_xmit(&queue);
        } else {
                dev_put(f->t->ifp->nd);
        }
        return 1;
}

/* some callers cannot sleep, and they can call this function,
 * transmitting the packets later, when interrupts are on
 */
static void
aoecmd_cfg_pkts(ushort aoemajor, unsigned char aoeminor, struct sk_buff_head *queue)
{
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        struct sk_buff *skb;
        struct net_device *ifp;

        rcu_read_lock();
        for_each_netdev_rcu(&init_net, ifp) {
                dev_hold(ifp);
                if (!is_aoe_netif(ifp)) {
                        dev_put(ifp);
                        continue;
                }

                skb = new_skb(sizeof *h + sizeof *ch);
                if (skb == NULL) {
                        printk(KERN_INFO "aoe: skb alloc failure\n");
                        dev_put(ifp);
                        continue;
                }
                skb_put(skb, sizeof *h + sizeof *ch);
                skb->dev = ifp;
                __skb_queue_tail(queue, skb);
                h = (struct aoe_hdr *) skb_mac_header(skb);
                memset(h, 0, sizeof *h + sizeof *ch);

                memset(h->dst, 0xff, sizeof h->dst);
                memcpy(h->src, ifp->dev_addr, sizeof h->src);
                h->type = __constant_cpu_to_be16(ETH_P_AOE);
                h->verfl = AOE_HVER;
                h->major = cpu_to_be16(aoemajor);
                h->minor = aoeminor;
                h->cmd = AOECMD_CFG;
        }
        rcu_read_unlock();
}

static void
resend(struct aoedev *d, struct frame *f)
{
        struct sk_buff *skb;
        struct sk_buff_head queue;
        struct aoe_hdr *h;
        struct aoetgt *t;
        char buf[128];
        u32 n;

        t = f->t;
        n = newtag(d);
        skb = f->skb;
        if (ifrotate(t) == NULL) {
                /* probably can't happen, but set it up to fail anyway */
                pr_info("aoe: resend: no interfaces to rotate to.\n");
                ktcomplete(f, NULL);
                return;
        }
        h = (struct aoe_hdr *) skb_mac_header(skb);

        if (!(f->flags & FFL_PROBE)) {
                snprintf(buf, sizeof(buf),
                        "%15s e%ld.%d oldtag=%08x@%08lx newtag=%08x s=%pm d=%pm nout=%d\n",
                        "retransmit", d->aoemajor, d->aoeminor,
                        f->tag, jiffies, n,
                        h->src, h->dst, t->nout);
                aoechr_error(buf);
        }

        f->tag = n;
        fhash(f);
        h->tag = cpu_to_be32(n);
        memcpy(h->dst, t->addr, sizeof h->dst);
        memcpy(h->src, t->ifp->nd->dev_addr, sizeof h->src);

        dev_hold(t->ifp->nd);
        skb->dev = t->ifp->nd;
        skb = skb_clone(skb, GFP_ATOMIC);
        if (skb == NULL) {
                dev_put(t->ifp->nd);
                return;
        }
        f->sent = ktime_get();
        __skb_queue_head_init(&queue);
        __skb_queue_tail(&queue, skb);
        aoenet_xmit(&queue);
}

static int
tsince_hr(struct frame *f)
{
        u64 delta = ktime_to_ns(ktime_sub(ktime_get(), f->sent));

        /* delta is normally under 4.2 seconds, avoid 64-bit division */
        if (likely(delta <= UINT_MAX))
                return (u32)delta / NSEC_PER_USEC;

        /* avoid overflow after 71 minutes */
        if (delta > ((u64)INT_MAX * NSEC_PER_USEC))
                return INT_MAX;

        return div_u64(delta, NSEC_PER_USEC);
}

static int
tsince(u32 tag)
{
        int n;

        n = jiffies & 0xffff;
        n -= tag & 0xffff;
        if (n < 0)
                n += 1<<16;
        return jiffies_to_usecs(n + 1);
}

static struct aoeif *
getif(struct aoetgt *t, struct net_device *nd)
{
        struct aoeif *p, *e;

        p = t->ifs;
        e = p + NAOEIFS;
        for (; p < e; p++)
                if (p->nd == nd)
                        return p;
        return NULL;
}

static void
ejectif(struct aoetgt *t, struct aoeif *ifp)
{
        struct aoeif *e;
        struct net_device *nd;
        ulong n;

        nd = ifp->nd;
        e = t->ifs + NAOEIFS - 1;
        n = (e - ifp) * sizeof *ifp;
        memmove(ifp, ifp+1, n);
        e->nd = NULL;
        dev_put(nd);
}

static struct frame *
reassign_frame(struct frame *f)
{
        struct frame *nf;
        struct sk_buff *skb;

        nf = newframe(f->t->d);
        if (!nf)
                return NULL;
        if (nf->t == f->t) {
                aoe_freetframe(nf);
                return NULL;
        }

        skb = nf->skb;
        nf->skb = f->skb;
        nf->buf = f->buf;
        nf->iter = f->iter;
        nf->waited = 0;
        nf->waited_total = f->waited_total;
        nf->sent = f->sent;
        f->skb = skb;

        return nf;
}

static void
probe(struct aoetgt *t)
{
        struct aoedev *d;
        struct frame *f;
        struct sk_buff *skb;
        struct sk_buff_head queue;
        size_t n, m;
        int frag;

        d = t->d;
        f = newtframe(d, t);
        if (!f) {
                pr_err("%s %pm for e%ld.%d: %s\n",
                        "aoe: cannot probe remote address",
                        t->addr,
                        (long) d->aoemajor, d->aoeminor,
                        "no frame available");
                return;
        }
        f->flags |= FFL_PROBE;
        ifrotate(t);
        f->iter.bi_size = t->d->maxbcnt ? t->d->maxbcnt : DEFAULTBCNT;
        ata_rw_frameinit(f);
        skb = f->skb;
        for (frag = 0, n = f->iter.bi_size; n > 0; ++frag, n -= m) {
                if (n < PAGE_SIZE)
                        m = n;
                else
                        m = PAGE_SIZE;
                skb_fill_page_desc(skb, frag, empty_page, 0, m);
        }
        skb->len += f->iter.bi_size;
        skb->data_len = f->iter.bi_size;
        skb->truesize += f->iter.bi_size;

        skb = skb_clone(f->skb, GFP_ATOMIC);
        if (skb) {
                f->sent = ktime_get();
                __skb_queue_head_init(&queue);
                __skb_queue_tail(&queue, skb);
                aoenet_xmit(&queue);
        } else {
                dev_put(f->t->ifp->nd);
        }
}

static long
rto(struct aoedev *d)
{
        long t;

        t = 2 * d->rttavg >> RTTSCALE;
        t += 8 * d->rttdev >> RTTDSCALE;
        if (t == 0)
                t = 1;

        return t;
}

static void
rexmit_deferred(struct aoedev *d)
{
        struct aoetgt *t;
        struct frame *f;
        struct frame *nf;
        struct list_head *pos, *nx, *head;
        int since;
        int untainted;

        count_targets(d, &untainted);

        head = &d->rexmitq;
        list_for_each_safe(pos, nx, head) {
                f = list_entry(pos, struct frame, head);
                t = f->t;
                if (t->taint) {
                        if (!(f->flags & FFL_PROBE)) {
                                nf = reassign_frame(f);
                                if (nf) {
                                        if (t->nout_probes == 0
                                        && untainted > 0) {
                                                probe(t);
                                                t->nout_probes++;
                                        }
                                        list_replace(&f->head, &nf->head);
                                        pos = &nf->head;
                                        aoe_freetframe(f);
                                        f = nf;
                                        t = f->t;
                                }
                        } else if (untainted < 1) {
                                /* don't probe w/o other untainted aoetgts */
                                goto stop_probe;
                        } else if (tsince_hr(f) < t->taint * rto(d)) {
                                /* reprobe slowly when taint is high */
                                continue;
                        }
                } else if (f->flags & FFL_PROBE) {
stop_probe:             /* don't probe untainted aoetgts */
                        list_del(pos);
                        aoe_freetframe(f);
                        /* leaving d->kicked, because this is routine */
                        f->t->d->flags |= DEVFL_KICKME;
                        continue;
                }
                if (t->nout >= t->maxout)
                        continue;
                list_del(pos);
                t->nout++;
                if (f->flags & FFL_PROBE)
                        t->nout_probes++;
                since = tsince_hr(f);
                f->waited += since;
                f->waited_total += since;
                resend(d, f);
        }
}

/* An aoetgt accumulates demerits quickly, and successful
 * probing redeems the aoetgt slowly.
 */
static void
scorn(struct aoetgt *t)
{
        int n;

        n = t->taint++;
        t->taint += t->taint * 2;
        if (n > t->taint)
                t->taint = n;
        if (t->taint > MAX_TAINT)
                t->taint = MAX_TAINT;
}

static int
count_targets(struct aoedev *d, int *untainted)
{
        int i, good;

        for (i = good = 0; i < d->ntargets && d->targets[i]; ++i)
                if (d->targets[i]->taint == 0)
                        good++;

        if (untainted)
                *untainted = good;
        return i;
}

static void
rexmit_timer(struct timer_list *timer)
{
        struct aoedev *d;
        struct aoetgt *t;
        struct aoeif *ifp;
        struct frame *f;
        struct list_head *head, *pos, *nx;
        LIST_HEAD(flist);
        register long timeout;
        ulong flags, n;
        int i;
        int utgts;      /* number of aoetgt descriptors (not slots) */
        int since;

        d = timer_container_of(d, timer, timer);

        spin_lock_irqsave(&d->lock, flags);

        /* timeout based on observed timings and variations */
        timeout = rto(d);

        utgts = count_targets(d, NULL);

        if (d->flags & (DEVFL_TKILL | DEVFL_DEAD)) {
                spin_unlock_irqrestore(&d->lock, flags);
                return;
        }

        /* collect all frames to rexmit into flist */
        for (i = 0; i < NFACTIVE; i++) {
                head = &d->factive[i];
                list_for_each_safe(pos, nx, head) {
                        f = list_entry(pos, struct frame, head);
                        if (tsince_hr(f) < timeout)
                                break;  /* end of expired frames */
                        /* move to flist for later processing */
                        list_move_tail(pos, &flist);
                }
        }

        /* process expired frames */
        while (!list_empty(&flist)) {
                pos = flist.next;
                f = list_entry(pos, struct frame, head);
                since = tsince_hr(f);
                n = f->waited_total + since;
                n /= USEC_PER_SEC;
                if (aoe_deadsecs
                && n > aoe_deadsecs
                && !(f->flags & FFL_PROBE)) {
                        /* Waited too long.  Device failure.
                         * Hang all frames on first hash bucket for downdev
                         * to clean up.
                         */
                        list_splice(&flist, &d->factive[0]);
                        d->flags |= DEVFL_DEAD;
                        queue_work(aoe_wq, &d->work);
                        goto out;
                }

                t = f->t;
                n = f->waited + since;
                n /= USEC_PER_SEC;
                if (aoe_deadsecs && utgts > 0
                && (n > aoe_deadsecs / utgts || n > HARD_SCORN_SECS))
                        scorn(t); /* avoid this target */

                if (t->maxout != 1) {
                        t->ssthresh = t->maxout / 2;
                        t->maxout = 1;
                }

                if (f->flags & FFL_PROBE) {
                        t->nout_probes--;
                } else {
                        ifp = getif(t, f->skb->dev);
                        if (ifp && ++ifp->lost > (t->nframes << 1)
                        && (ifp != t->ifs || t->ifs[1].nd)) {
                                ejectif(t, ifp);
                                ifp = NULL;
                        }
                }
                list_move_tail(pos, &d->rexmitq);
                t->nout--;
        }
        rexmit_deferred(d);

out:
        if ((d->flags & DEVFL_KICKME) && d->blkq) {
                d->flags &= ~DEVFL_KICKME;
                blk_mq_run_hw_queues(d->blkq, true);
        }

        d->timer.expires = jiffies + TIMERTICK;
        add_timer(&d->timer);

        spin_unlock_irqrestore(&d->lock, flags);
}

static void
bufinit(struct buf *buf, struct request *rq, struct bio *bio)
{
        memset(buf, 0, sizeof(*buf));
        buf->rq = rq;
        buf->bio = bio;
        buf->iter = bio->bi_iter;
}

static struct buf *
nextbuf(struct aoedev *d)
{
        struct request *rq;
        struct request_queue *q;
        struct aoe_req *req;
        struct buf *buf;
        struct bio *bio;

        q = d->blkq;
        if (q == NULL)
                return NULL;    /* initializing */
        if (d->ip.buf)
                return d->ip.buf;
        rq = d->ip.rq;
        if (rq == NULL) {
                rq = list_first_entry_or_null(&d->rq_list, struct request,
                                                queuelist);
                if (rq == NULL)
                        return NULL;
                list_del_init(&rq->queuelist);
                blk_mq_start_request(rq);
                d->ip.rq = rq;
                d->ip.nxbio = rq->bio;

                req = blk_mq_rq_to_pdu(rq);
                req->nr_bios = 0;
                __rq_for_each_bio(bio, rq)
                        req->nr_bios++;
        }
        buf = mempool_alloc(d->bufpool, GFP_ATOMIC);
        if (buf == NULL) {
                pr_err("aoe: nextbuf: unable to mempool_alloc!\n");
                return NULL;
        }
        bio = d->ip.nxbio;
        bufinit(buf, rq, bio);
        bio = bio->bi_next;
        d->ip.nxbio = bio;
        if (bio == NULL)
                d->ip.rq = NULL;
        return d->ip.buf = buf;
}

/* enters with d->lock held */
void
aoecmd_work(struct aoedev *d)
{
        rexmit_deferred(d);
        while (aoecmd_ata_rw(d))
                ;
}

/* this function performs work that has been deferred until sleeping is OK
 */
void
aoecmd_sleepwork(struct work_struct *work)
{
        struct aoedev *d = container_of(work, struct aoedev, work);

        if (d->flags & DEVFL_DEAD)
                aoedev_downdev(d);

        if (d->flags & DEVFL_GDALLOC)
                aoeblk_gdalloc(d);

        if (d->flags & DEVFL_NEWSIZE) {
                set_capacity_and_notify(d->gd, d->ssize);

                spin_lock_irq(&d->lock);
                d->flags |= DEVFL_UP;
                d->flags &= ~DEVFL_NEWSIZE;
                spin_unlock_irq(&d->lock);
        }
}

static void
ata_ident_fixstring(u16 *id, int ns)
{
        u16 s;

        while (ns-- > 0) {
                s = *id;
                *id++ = s >> 8 | s << 8;
        }
}

static void
ataid_complete(struct aoedev *d, struct aoetgt *t, unsigned char *id)
{
        u64 ssize;
        u16 n;

        /* word 83: command set supported */
        n = get_unaligned_le16(&id[83 << 1]);

        /* word 86: command set/feature enabled */
        n |= get_unaligned_le16(&id[86 << 1]);

        if (n & (1<<10)) {      /* bit 10: LBA 48 */
                d->flags |= DEVFL_EXT;

                /* word 100: number lba48 sectors */
                ssize = get_unaligned_le64(&id[100 << 1]);

                /* set as in ide-disk.c:init_idedisk_capacity */
                d->geo.cylinders = ssize;
                d->geo.cylinders /= (255 * 63);
                d->geo.heads = 255;
                d->geo.sectors = 63;
        } else {
                d->flags &= ~DEVFL_EXT;

                /* number lba28 sectors */
                ssize = get_unaligned_le32(&id[60 << 1]);

                /* NOTE: obsolete in ATA 6 */
                d->geo.cylinders = get_unaligned_le16(&id[54 << 1]);
                d->geo.heads = get_unaligned_le16(&id[55 << 1]);
                d->geo.sectors = get_unaligned_le16(&id[56 << 1]);
        }

        ata_ident_fixstring((u16 *) &id[10<<1], 10);    /* serial */
        ata_ident_fixstring((u16 *) &id[23<<1], 4);     /* firmware */
        ata_ident_fixstring((u16 *) &id[27<<1], 20);    /* model */
        memcpy(d->ident, id, sizeof(d->ident));

        if (d->ssize != ssize)
                printk(KERN_INFO
                        "aoe: %pm e%ld.%d v%04x has %llu sectors\n",
                        t->addr,
                        d->aoemajor, d->aoeminor,
                        d->fw_ver, (long long)ssize);
        d->ssize = ssize;
        d->geo.start = 0;
        if (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
                return;
        if (d->gd != NULL)
                d->flags |= DEVFL_NEWSIZE;
        else
                d->flags |= DEVFL_GDALLOC;
        queue_work(aoe_wq, &d->work);
}

static void
calc_rttavg(struct aoedev *d, struct aoetgt *t, int rtt)
{
        register long n;

        n = rtt;

        /* cf. Congestion Avoidance and Control, Jacobson & Karels, 1988 */
        n -= d->rttavg >> RTTSCALE;
        d->rttavg += n;
        if (n < 0)
                n = -n;
        n -= d->rttdev >> RTTDSCALE;
        d->rttdev += n;

        if (!t || t->maxout >= t->nframes)
                return;
        if (t->maxout < t->ssthresh)
                t->maxout += 1;
        else if (t->nout == t->maxout && t->next_cwnd-- == 0) {
                t->maxout += 1;
                t->next_cwnd = t->maxout;
        }
}

static struct aoetgt *
gettgt(struct aoedev *d, char *addr)
{
        struct aoetgt **t, **e;

        t = d->targets;
        e = t + d->ntargets;
        for (; t < e && *t; t++)
                if (memcmp((*t)->addr, addr, sizeof((*t)->addr)) == 0)
                        return *t;
        return NULL;
}

static void
bvcpy(struct sk_buff *skb, struct bio *bio, struct bvec_iter iter, long cnt)
{
        int soff = 0;
        struct bio_vec bv;

        iter.bi_size = cnt;

        __bio_for_each_segment(bv, bio, iter, iter) {
                char *p = bvec_kmap_local(&bv);
                skb_copy_bits(skb, soff, p, bv.bv_len);
                kunmap_local(p);
                soff += bv.bv_len;
        }
}

void
aoe_end_request(struct aoedev *d, struct request *rq, int fastfail)
{
        struct bio *bio;
        int bok;
        struct request_queue *q;
        blk_status_t err = BLK_STS_OK;

        q = d->blkq;
        if (rq == d->ip.rq)
                d->ip.rq = NULL;
        do {
                bio = rq->bio;
                bok = !fastfail && !bio->bi_status;
                if (!bok)
                        err = BLK_STS_IOERR;
        } while (blk_update_request(rq, bok ? BLK_STS_OK : BLK_STS_IOERR, bio->bi_iter.bi_size));

        __blk_mq_end_request(rq, err);

        /* cf. https://lore.kernel.org/lkml/20061031071040.GS14055@kernel.dk/ */
        if (!fastfail)
                blk_mq_run_hw_queues(q, true);
}

static void
aoe_end_buf(struct aoedev *d, struct buf *buf)
{
        struct request *rq = buf->rq;
        struct aoe_req *req = blk_mq_rq_to_pdu(rq);

        if (buf == d->ip.buf)
                d->ip.buf = NULL;
        mempool_free(buf, d->bufpool);
        if (--req->nr_bios == 0)
                aoe_end_request(d, rq, 0);
}

static void
ktiocomplete(struct frame *f)
{
        struct aoe_hdr *hin, *hout;
        struct aoe_atahdr *ahin, *ahout;
        struct buf *buf;
        struct sk_buff *skb;
        struct aoetgt *t;
        struct aoeif *ifp;
        struct aoedev *d;
        long n;
        int untainted;

        if (f == NULL)
                return;

        t = f->t;
        d = t->d;
        skb = f->r_skb;
        buf = f->buf;
        if (f->flags & FFL_PROBE)
                goto out;
        if (!skb)               /* just fail the buf. */
                goto noskb;

        hout = (struct aoe_hdr *) skb_mac_header(f->skb);
        ahout = (struct aoe_atahdr *) (hout+1);

        hin = (struct aoe_hdr *) skb->data;
        skb_pull(skb, sizeof(*hin));
        ahin = (struct aoe_atahdr *) skb->data;
        skb_pull(skb, sizeof(*ahin));
        if (ahin->cmdstat & 0xa9) {     /* these bits cleared on success */
                pr_err("aoe: ata error cmd=%2.2Xh stat=%2.2Xh from e%ld.%d\n",
                        ahout->cmdstat, ahin->cmdstat,
                        d->aoemajor, d->aoeminor);
noskb:          if (buf)
                        buf->bio->bi_status = BLK_STS_IOERR;
                goto out;
        }

        n = ahout->scnt << 9;
        switch (ahout->cmdstat) {
        case ATA_CMD_PIO_READ:
        case ATA_CMD_PIO_READ_EXT:
                if (skb->len < n) {
                        pr_err("%s e%ld.%d.  skb->len=%d need=%ld\n",
                                "aoe: runt data size in read from",
                                (long) d->aoemajor, d->aoeminor,
                               skb->len, n);
                        buf->bio->bi_status = BLK_STS_IOERR;
                        break;
                }
                if (n > f->iter.bi_size) {
                        pr_err_ratelimited("%s e%ld.%d.  bytes=%ld need=%u\n",
                                "aoe: too-large data size in read from",
                                (long) d->aoemajor, d->aoeminor,
                                n, f->iter.bi_size);
                        buf->bio->bi_status = BLK_STS_IOERR;
                        break;
                }
                bvcpy(skb, f->buf->bio, f->iter, n);
                fallthrough;
        case ATA_CMD_PIO_WRITE:
        case ATA_CMD_PIO_WRITE_EXT:
                spin_lock_irq(&d->lock);
                ifp = getif(t, skb->dev);
                if (ifp)
                        ifp->lost = 0;
                spin_unlock_irq(&d->lock);
                break;
        case ATA_CMD_ID_ATA:
                if (skb->len < 512) {
                        pr_info("%s e%ld.%d.  skb->len=%d need=512\n",
                                "aoe: runt data size in ataid from",
                                (long) d->aoemajor, d->aoeminor,
                                skb->len);
                        break;
                }
                if (skb_linearize(skb))
                        break;
                spin_lock_irq(&d->lock);
                ataid_complete(d, t, skb->data);
                spin_unlock_irq(&d->lock);
                break;
        default:
                pr_info("aoe: unrecognized ata command %2.2Xh for %d.%d\n",
                        ahout->cmdstat,
                        be16_to_cpu(get_unaligned(&hin->major)),
                        hin->minor);
        }
out:
        spin_lock_irq(&d->lock);
        if (t->taint > 0
        && --t->taint > 0
        && t->nout_probes == 0) {
                count_targets(d, &untainted);
                if (untainted > 0) {
                        probe(t);
                        t->nout_probes++;
                }
        }

        aoe_freetframe(f);

        if (buf && --buf->nframesout == 0 && buf->iter.bi_size == 0)
                aoe_end_buf(d, buf);

        spin_unlock_irq(&d->lock);
        aoedev_put(d);
        dev_kfree_skb(skb);
}

/* Enters with iocq.lock held.
 * Returns true iff responses needing processing remain.
 */
static int
ktio(int id)
{
        struct frame *f;
        struct list_head *pos;
        int i;
        int actual_id;

        for (i = 0; ; ++i) {
                if (i == MAXIOC)
                        return 1;
                if (list_empty(&iocq[id].head))
                        return 0;
                pos = iocq[id].head.next;
                list_del(pos);
                f = list_entry(pos, struct frame, head);
                spin_unlock_irq(&iocq[id].lock);
                ktiocomplete(f);

                /* Figure out if extra threads are required. */
                actual_id = f->t->d->aoeminor % ncpus;

                if (!kts[actual_id].active) {
                        BUG_ON(id != 0);
                        mutex_lock(&ktio_spawn_lock);
                        if (!kts[actual_id].active
                                && aoe_ktstart(&kts[actual_id]) == 0)
                                kts[actual_id].active = 1;
                        mutex_unlock(&ktio_spawn_lock);
                }
                spin_lock_irq(&iocq[id].lock);
        }
}

static int
kthread(void *vp)
{
        struct ktstate *k;
        DECLARE_WAITQUEUE(wait, current);
        int more;

        k = vp;
        current->flags |= PF_NOFREEZE;
        set_user_nice(current, -10);
        complete(&k->rendez);   /* tell spawner we're running */
        do {
                spin_lock_irq(k->lock);
                more = k->fn(k->id);
                if (!more) {
                        add_wait_queue(k->waitq, &wait);
                        __set_current_state(TASK_INTERRUPTIBLE);
                }
                spin_unlock_irq(k->lock);
                if (!more) {
                        schedule();
                        remove_wait_queue(k->waitq, &wait);
                } else
                        cond_resched();
        } while (!kthread_should_stop());
        complete(&k->rendez);   /* tell spawner we're stopping */
        return 0;
}

void
aoe_ktstop(struct ktstate *k)
{
        kthread_stop(k->task);
        wait_for_completion(&k->rendez);
}

int
aoe_ktstart(struct ktstate *k)
{
        struct task_struct *task;

        init_completion(&k->rendez);
        task = kthread_run(kthread, k, "%s", k->name);
        if (task == NULL || IS_ERR(task))
                return -ENOMEM;
        k->task = task;
        wait_for_completion(&k->rendez); /* allow kthread to start */
        init_completion(&k->rendez);    /* for waiting for exit later */
        return 0;
}

/* pass it off to kthreads for processing */
static void
ktcomplete(struct frame *f, struct sk_buff *skb)
{
        int id;
        ulong flags;

        f->r_skb = skb;
        id = f->t->d->aoeminor % ncpus;
        spin_lock_irqsave(&iocq[id].lock, flags);
        if (!kts[id].active) {
                spin_unlock_irqrestore(&iocq[id].lock, flags);
                /* The thread with id has not been spawned yet,
                 * so delegate the work to the main thread and
                 * try spawning a new thread.
                 */
                id = 0;
                spin_lock_irqsave(&iocq[id].lock, flags);
        }
        list_add_tail(&f->head, &iocq[id].head);
        spin_unlock_irqrestore(&iocq[id].lock, flags);
        wake_up(&ktiowq[id]);
}

struct sk_buff *
aoecmd_ata_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *h;
        struct frame *f;
        u32 n;
        ulong flags;
        char ebuf[128];
        u16 aoemajor;

        h = (struct aoe_hdr *) skb->data;
        aoemajor = be16_to_cpu(get_unaligned(&h->major));
        d = aoedev_by_aoeaddr(aoemajor, h->minor, 0);
        if (d == NULL) {
                snprintf(ebuf, sizeof ebuf, "aoecmd_ata_rsp: ata response "
                        "for unknown device %d.%d\n",
                        aoemajor, h->minor);
                aoechr_error(ebuf);
                return skb;
        }

        spin_lock_irqsave(&d->lock, flags);

        n = be32_to_cpu(get_unaligned(&h->tag));
        f = getframe(d, n);
        if (f) {
                calc_rttavg(d, f->t, tsince_hr(f));
                f->t->nout--;
                if (f->flags & FFL_PROBE)
                        f->t->nout_probes--;
        } else {
                f = getframe_deferred(d, n);
                if (f) {
                        calc_rttavg(d, NULL, tsince_hr(f));
                } else {
                        calc_rttavg(d, NULL, tsince(n));
                        spin_unlock_irqrestore(&d->lock, flags);
                        aoedev_put(d);
                        snprintf(ebuf, sizeof(ebuf),
                                 "%15s e%d.%d    tag=%08x@%08lx s=%pm d=%pm\n",
                                 "unexpected rsp",
                                 get_unaligned_be16(&h->major),
                                 h->minor,
                                 get_unaligned_be32(&h->tag),
                                 jiffies,
                                 h->src,
                                 h->dst);
                        aoechr_error(ebuf);
                        return skb;
                }
        }
        aoecmd_work(d);

        spin_unlock_irqrestore(&d->lock, flags);

        ktcomplete(f, skb);

        /*
         * Note here that we do not perform an aoedev_put, as we are
         * leaving this reference for the ktio to release.
         */
        return NULL;
}

void
aoecmd_cfg(ushort aoemajor, unsigned char aoeminor)
{
        struct sk_buff_head queue;

        __skb_queue_head_init(&queue);
        aoecmd_cfg_pkts(aoemajor, aoeminor, &queue);
        aoenet_xmit(&queue);
}

struct sk_buff *
aoecmd_ata_id(struct aoedev *d)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct frame *f;
        struct sk_buff *skb;
        struct aoetgt *t;

        f = newframe(d);
        if (f == NULL)
                return NULL;

        t = *d->tgt;

        /* initialize the headers & frame */
        skb = f->skb;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ah = (struct aoe_atahdr *) (h+1);
        skb_put(skb, sizeof *h + sizeof *ah);
        memset(h, 0, skb->len);
        f->tag = aoehdr_atainit(d, t, h);
        fhash(f);
        t->nout++;
        f->waited = 0;
        f->waited_total = 0;

        /* set up ata header */
        ah->scnt = 1;
        ah->cmdstat = ATA_CMD_ID_ATA;
        ah->lba3 = 0xa0;

        dev_hold(t->ifp->nd);
        skb->dev = t->ifp->nd;

        d->rttavg = RTTAVG_INIT;
        d->rttdev = RTTDEV_INIT;
        d->timer.function = rexmit_timer;

        skb = skb_clone(skb, GFP_ATOMIC);
        if (skb)
                f->sent = ktime_get();
        else
                dev_put(t->ifp->nd);

        return skb;
}

static struct aoetgt **
grow_targets(struct aoedev *d)
{
        ulong oldn, newn;
        struct aoetgt **tt;

        oldn = d->ntargets;
        newn = oldn * 2;
        tt = kzalloc_objs(*d->targets, newn, GFP_ATOMIC);
        if (!tt)
                return NULL;
        memmove(tt, d->targets, sizeof(*d->targets) * oldn);
        d->tgt = tt + (d->tgt - d->targets);
        kfree(d->targets);
        d->targets = tt;
        d->ntargets = newn;

        return &d->targets[oldn];
}

static struct aoetgt *
addtgt(struct aoedev *d, char *addr, ulong nframes)
{
        struct aoetgt *t, **tt, **te;

        tt = d->targets;
        te = tt + d->ntargets;
        for (; tt < te && *tt; tt++)
                ;

        if (tt == te) {
                tt = grow_targets(d);
                if (!tt)
                        goto nomem;
        }
        t = kzalloc_obj(*t, GFP_ATOMIC);
        if (!t)
                goto nomem;
        t->nframes = nframes;
        t->d = d;
        memcpy(t->addr, addr, sizeof t->addr);
        t->ifp = t->ifs;
        aoecmd_wreset(t);
        t->maxout = t->nframes / 2;
        INIT_LIST_HEAD(&t->ffree);
        return *tt = t;

 nomem:
        pr_info("aoe: cannot allocate memory to add target\n");
        return NULL;
}

static void
setdbcnt(struct aoedev *d)
{
        struct aoetgt **t, **e;
        int bcnt = 0;

        t = d->targets;
        e = t + d->ntargets;
        for (; t < e && *t; t++)
                if (bcnt == 0 || bcnt > (*t)->minbcnt)
                        bcnt = (*t)->minbcnt;
        if (bcnt != d->maxbcnt) {
                d->maxbcnt = bcnt;
                pr_info("aoe: e%ld.%d: setting %d byte data frames\n",
                        d->aoemajor, d->aoeminor, bcnt);
        }
}

static void
setifbcnt(struct aoetgt *t, struct net_device *nd, int bcnt)
{
        struct aoedev *d;
        struct aoeif *p, *e;
        int minbcnt;

        d = t->d;
        minbcnt = bcnt;
        p = t->ifs;
        e = p + NAOEIFS;
        for (; p < e; p++) {
                if (p->nd == NULL)
                        break;          /* end of the valid interfaces */
                if (p->nd == nd) {
                        p->bcnt = bcnt; /* we're updating */
                        nd = NULL;
                } else if (minbcnt > p->bcnt)
                        minbcnt = p->bcnt; /* find the min interface */
        }
        if (nd) {
                if (p == e) {
                        pr_err("aoe: device setifbcnt failure; too many interfaces.\n");
                        return;
                }
                dev_hold(nd);
                p->nd = nd;
                p->bcnt = bcnt;
        }
        t->minbcnt = minbcnt;
        setdbcnt(d);
}

void
aoecmd_cfg_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        struct aoetgt *t;
        ulong flags, aoemajor;
        struct sk_buff *sl;
        struct sk_buff_head queue;
        u16 n;

        sl = NULL;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ch = (struct aoe_cfghdr *) (h+1);

        /*
         * Enough people have their dip switches set backwards to
         * warrant a loud message for this special case.
         */
        aoemajor = get_unaligned_be16(&h->major);
        if (aoemajor == 0xfff) {
                printk(KERN_ERR "aoe: Warning: shelf address is all ones.  "
                        "Check shelf dip switches.\n");
                return;
        }
        if (aoemajor == 0xffff) {
                pr_info("aoe: e%ld.%d: broadcast shelf number invalid\n",
                        aoemajor, (int) h->minor);
                return;
        }
        if (h->minor == 0xff) {
                pr_info("aoe: e%ld.%d: broadcast slot number invalid\n",
                        aoemajor, (int) h->minor);
                return;
        }

        n = be16_to_cpu(ch->bufcnt);
        if (n > aoe_maxout)     /* keep it reasonable */
                n = aoe_maxout;

        d = aoedev_by_aoeaddr(aoemajor, h->minor, 1);
        if (d == NULL) {
                pr_info("aoe: device allocation failure\n");
                return;
        }

        spin_lock_irqsave(&d->lock, flags);

        t = gettgt(d, h->src);
        if (t) {
                t->nframes = n;
                if (n < t->maxout)
                        aoecmd_wreset(t);
        } else {
                t = addtgt(d, h->src, n);
                if (!t)
                        goto bail;
        }
        n = skb->dev->mtu;
        n -= sizeof(struct aoe_hdr) + sizeof(struct aoe_atahdr);
        n /= 512;
        if (n > ch->scnt)
                n = ch->scnt;
        n = n ? n * 512 : DEFAULTBCNT;
        setifbcnt(t, skb->dev, n);

        /* don't change users' perspective */
        if (d->nopen == 0) {
                d->fw_ver = be16_to_cpu(ch->fwver);
                sl = aoecmd_ata_id(d);
        }
bail:
        spin_unlock_irqrestore(&d->lock, flags);
        aoedev_put(d);
        if (sl) {
                __skb_queue_head_init(&queue);
                __skb_queue_tail(&queue, sl);
                aoenet_xmit(&queue);
        }
}

void
aoecmd_wreset(struct aoetgt *t)
{
        t->maxout = 1;
        t->ssthresh = t->nframes / 2;
        t->next_cwnd = t->nframes;
}

void
aoecmd_cleanslate(struct aoedev *d)
{
        struct aoetgt **t, **te;

        d->rttavg = RTTAVG_INIT;
        d->rttdev = RTTDEV_INIT;
        d->maxbcnt = 0;

        t = d->targets;
        te = t + d->ntargets;
        for (; t < te && *t; t++)
                aoecmd_wreset(*t);
}

void
aoe_failbuf(struct aoedev *d, struct buf *buf)
{
        if (buf == NULL)
                return;
        buf->iter.bi_size = 0;
        buf->bio->bi_status = BLK_STS_IOERR;
        if (buf->nframesout == 0)
                aoe_end_buf(d, buf);
}

void
aoe_flush_iocq(void)
{
        int i;

        for (i = 0; i < ncpus; i++) {
                if (kts[i].active)
                        aoe_flush_iocq_by_index(i);
        }
}

void
aoe_flush_iocq_by_index(int id)
{
        struct frame *f;
        struct aoedev *d;
        LIST_HEAD(flist);
        struct list_head *pos;
        struct sk_buff *skb;
        ulong flags;

        spin_lock_irqsave(&iocq[id].lock, flags);
        list_splice_init(&iocq[id].head, &flist);
        spin_unlock_irqrestore(&iocq[id].lock, flags);
        while (!list_empty(&flist)) {
                pos = flist.next;
                list_del(pos);
                f = list_entry(pos, struct frame, head);
                d = f->t->d;
                skb = f->r_skb;
                spin_lock_irqsave(&d->lock, flags);
                if (f->buf) {
                        f->buf->nframesout--;
                        aoe_failbuf(d, f->buf);
                }
                aoe_freetframe(f);
                spin_unlock_irqrestore(&d->lock, flags);
                dev_kfree_skb(skb);
                aoedev_put(d);
        }
}

int __init
aoecmd_init(void)
{
        void *p;
        int i;
        int ret;

        /* get_zeroed_page returns page with ref count 1 */
        p = (void *) get_zeroed_page(GFP_KERNEL);
        if (!p)
                return -ENOMEM;
        empty_page = virt_to_page(p);

        ncpus = num_online_cpus();

        iocq = kzalloc_objs(struct iocq_ktio, ncpus);
        if (!iocq)
                return -ENOMEM;

        kts = kzalloc_objs(struct ktstate, ncpus);
        if (!kts) {
                ret = -ENOMEM;
                goto kts_fail;
        }

        ktiowq = kzalloc_objs(wait_queue_head_t, ncpus);
        if (!ktiowq) {
                ret = -ENOMEM;
                goto ktiowq_fail;
        }

        for (i = 0; i < ncpus; i++) {
                INIT_LIST_HEAD(&iocq[i].head);
                spin_lock_init(&iocq[i].lock);
                init_waitqueue_head(&ktiowq[i]);
                snprintf(kts[i].name, sizeof(kts[i].name), "aoe_ktio%d", i);
                kts[i].fn = ktio;
                kts[i].waitq = &ktiowq[i];
                kts[i].lock = &iocq[i].lock;
                kts[i].id = i;
                kts[i].active = 0;
        }
        kts[0].active = 1;
        if (aoe_ktstart(&kts[0])) {
                ret = -ENOMEM;
                goto ktstart_fail;
        }
        return 0;

ktstart_fail:
        kfree(ktiowq);
ktiowq_fail:
        kfree(kts);
kts_fail:
        kfree(iocq);

        return ret;
}

void
aoecmd_exit(void)
{
        int i;

        for (i = 0; i < ncpus; i++)
                if (kts[i].active)
                        aoe_ktstop(&kts[i]);

        aoe_flush_iocq();

        /* Free up the iocq and thread speicific configuration
        * allocated during startup.
        */
        kfree(iocq);
        kfree(kts);
        kfree(ktiowq);

        __free_page(empty_page);
        empty_page = NULL;
}