drivers/block/aoe/aoecmd.c

   1 /* Copyright (c) 2006 Coraid, Inc.  See COPYING for GPL terms. */
   2 /*
   3  * aoecmd.c
   4  * Filesystem request handling methods
   5  */
   6
   7 #include <linux/hdreg.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/netdevice.h>
  11 #include <linux/genhd.h>
  12 #include <asm/unaligned.h>
  13 #include "aoe.h"
  14
  15 #define TIMERTICK (HZ / 10)
  16 #define MINTIMER (2 * TIMERTICK)
  17 #define MAXTIMER (HZ << 1)
  18 #define MAXWAIT (60 * 3)        /* After MAXWAIT seconds, give up and fail dev */
  19
  20 struct sk_buff *
  21 new_skb(ulong len)
  22 {
  23         struct sk_buff *skb;
  24
  25         skb = alloc_skb(len, GFP_ATOMIC);
  26         if (skb) {
  27                 skb->nh.raw = skb->mac.raw = skb->data;
  28                 skb->protocol = __constant_htons(ETH_P_AOE);
  29                 skb->priority = 0;
  30                 skb_put(skb, len);
  31                 memset(skb->head, 0, len);
  32                 skb->next = skb->prev = NULL;
  33
  34                 /* tell the network layer not to perform IP checksums
  35                  * or to get the NIC to do it
  36                  */
  37                 skb->ip_summed = CHECKSUM_NONE;
  38         }
  39         return skb;
  40 }
  41
  42 static struct frame *
  43 getframe(struct aoedev *d, int tag)
  44 {
  45         struct frame *f, *e;
  46
  47         f = d->frames;
  48         e = f + d->nframes;
  49         for (; f<e; f++)
  50                 if (f->tag == tag)
  51                         return f;
  52         return NULL;
  53 }
  54
  55 /*
  56  * Leave the top bit clear so we have tagspace for userland.
  57  * The bottom 16 bits are the xmit tick for rexmit/rttavg processing.
  58  * This driver reserves tag -1 to mean "unused frame."
  59  */
  60 static int
  61 newtag(struct aoedev *d)
  62 {
  63         register ulong n;
  64
  65         n = jiffies & 0xffff;
  66         return n |= (++d->lasttag & 0x7fff) << 16;
  67 }
  68
  69 static int
  70 aoehdr_atainit(struct aoedev *d, struct aoe_hdr *h)
  71 {
  72         u32 host_tag = newtag(d);
  73
  74         memcpy(h->src, d->ifp->dev_addr, sizeof h->src);
  75         memcpy(h->dst, d->addr, sizeof h->dst);
  76         h->type = __constant_cpu_to_be16(ETH_P_AOE);
  77         h->verfl = AOE_HVER;
  78         h->major = cpu_to_be16(d->aoemajor);
  79         h->minor = d->aoeminor;
  80         h->cmd = AOECMD_ATA;
  81         h->tag = cpu_to_be32(host_tag);
  82
  83         return host_tag;
  84 }
  85
  86 static inline void
  87 put_lba(struct aoe_atahdr *ah, sector_t lba)
  88 {
  89         ah->lba0 = lba;
  90         ah->lba1 = lba >>= 8;
  91         ah->lba2 = lba >>= 8;
  92         ah->lba3 = lba >>= 8;
  93         ah->lba4 = lba >>= 8;
  94         ah->lba5 = lba >>= 8;
  95 }
  96
  97 static void
  98 aoecmd_ata_rw(struct aoedev *d, struct frame *f)
  99 {
 100         struct aoe_hdr *h;
 101         struct aoe_atahdr *ah;
 102         struct buf *buf;
 103         struct sk_buff *skb;
 104         ulong bcnt;
 105         register sector_t sector;
 106         char writebit, extbit;
 107
 108         writebit = 0x10;
 109         extbit = 0x4;
 110
 111         buf = d->inprocess;
 112
 113         sector = buf->sector;
 114         bcnt = buf->bv_resid;
 115         if (bcnt > d->maxbcnt)
 116                 bcnt = d->maxbcnt;
 117
 118         /* initialize the headers & frame */
 119         skb = f->skb;
 120         h = (struct aoe_hdr *) skb->mac.raw;
 121         ah = (struct aoe_atahdr *) (h+1);
 122         skb->len = sizeof *h + sizeof *ah;
 123         memset(h, 0, skb->len);
 124         f->tag = aoehdr_atainit(d, h);
 125         f->waited = 0;
 126         f->buf = buf;
 127         f->bufaddr = buf->bufaddr;
 128         f->bcnt = bcnt;
 129         f->lba = sector;
 130
 131         /* set up ata header */
 132         ah->scnt = bcnt >> 9;
 133         put_lba(ah, sector);
 134         if (d->flags & DEVFL_EXT) {
 135                 ah->aflags |= AOEAFL_EXT;
 136         } else {
 137                 extbit = 0;
 138                 ah->lba3 &= 0x0f;
 139                 ah->lba3 |= 0xe0;       /* LBA bit + obsolete 0xa0 */
 140         }
 141
 142         if (bio_data_dir(buf->bio) == WRITE) {
 143                 skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
 144                         offset_in_page(f->bufaddr), bcnt);
 145                 ah->aflags |= AOEAFL_WRITE;
 146         } else {
 147                 skb_shinfo(skb)->nr_frags = 0;
 148                 skb->len = ETH_ZLEN;
 149                 writebit = 0;
 150         }
 151
 152         ah->cmdstat = WIN_READ | writebit | extbit;
 153
 154         /* mark all tracking fields and load out */
 155         buf->nframesout += 1;
 156         buf->bufaddr += bcnt;
 157         buf->bv_resid -= bcnt;
 158 /* printk(KERN_INFO "aoe: bv_resid=%ld\n", buf->bv_resid); */
 159         buf->resid -= bcnt;
 160         buf->sector += bcnt >> 9;
 161         if (buf->resid == 0) {
 162                 d->inprocess = NULL;
 163         } else if (buf->bv_resid == 0) {
 164                 buf->bv++;
 165                 buf->bv_resid = buf->bv->bv_len;
 166                 buf->bufaddr = page_address(buf->bv->bv_page) + buf->bv->bv_offset;
 167         }
 168
 169         skb->dev = d->ifp;
 170         skb_get(skb);
 171         skb->next = NULL;
 172         if (d->sendq_hd)
 173                 d->sendq_tl->next = skb;
 174         else
 175                 d->sendq_hd = skb;
 176         d->sendq_tl = skb;
 177 }
 178
 179 /* some callers cannot sleep, and they can call this function,
 180  * transmitting the packets later, when interrupts are on
 181  */
 182 static struct sk_buff *
 183 aoecmd_cfg_pkts(ushort aoemajor, unsigned char aoeminor, struct sk_buff **tail)
 184 {
 185         struct aoe_hdr *h;
 186         struct aoe_cfghdr *ch;
 187         struct sk_buff *skb, *sl, *sl_tail;
 188         struct net_device *ifp;
 189
 190         sl = sl_tail = NULL;
 191
 192         read_lock(&dev_base_lock);
 193         for (ifp = dev_base; ifp; dev_put(ifp), ifp = ifp->next) {
 194                 dev_hold(ifp);
 195                 if (!is_aoe_netif(ifp))
 196                         continue;
 197
 198                 skb = new_skb(sizeof *h + sizeof *ch);
 199                 if (skb == NULL) {
 200                         printk(KERN_INFO "aoe: aoecmd_cfg: skb alloc failure\n");
 201                         continue;
 202                 }
 203                 skb->dev = ifp;
 204                 if (sl_tail == NULL)
 205                         sl_tail = skb;
 206                 h = (struct aoe_hdr *) skb->mac.raw;
 207                 memset(h, 0, sizeof *h + sizeof *ch);
 208
 209                 memset(h->dst, 0xff, sizeof h->dst);
 210                 memcpy(h->src, ifp->dev_addr, sizeof h->src);
 211                 h->type = __constant_cpu_to_be16(ETH_P_AOE);
 212                 h->verfl = AOE_HVER;
 213                 h->major = cpu_to_be16(aoemajor);
 214                 h->minor = aoeminor;
 215                 h->cmd = AOECMD_CFG;
 216
 217                 skb->next = sl;
 218                 sl = skb;
 219         }
 220         read_unlock(&dev_base_lock);
 221
 222         if (tail != NULL)
 223                 *tail = sl_tail;
 224         return sl;
 225 }
 226
 227 /* enters with d->lock held */
 228 void
 229 aoecmd_work(struct aoedev *d)
 230 {
 231         struct frame *f;
 232         struct buf *buf;
 233
 234         if (d->flags & DEVFL_PAUSE) {
 235                 if (!aoedev_isbusy(d))
 236                         d->sendq_hd = aoecmd_cfg_pkts(d->aoemajor,
 237                                                 d->aoeminor, &d->sendq_tl);
 238                 return;
 239         }
 240
 241 loop:
 242         f = getframe(d, FREETAG);
 243         if (f == NULL)
 244                 return;
 245         if (d->inprocess == NULL) {
 246                 if (list_empty(&d->bufq))
 247                         return;
 248                 buf = container_of(d->bufq.next, struct buf, bufs);
 249                 list_del(d->bufq.next);
 250 /*printk(KERN_INFO "aoecmd_work: bi_size=%ld\n", buf->bio->bi_size); */
 251                 d->inprocess = buf;
 252         }
 253         aoecmd_ata_rw(d, f);
 254         goto loop;
 255 }
 256
 257 static void
 258 rexmit(struct aoedev *d, struct frame *f)
 259 {
 260         struct sk_buff *skb;
 261         struct aoe_hdr *h;
 262         struct aoe_atahdr *ah;
 263         char buf[128];
 264         u32 n;
 265
 266         n = newtag(d);
 267
 268         snprintf(buf, sizeof buf,
 269                 "%15s e%ld.%ld oldtag=%08x@%08lx newtag=%08x\n",
 270                 "retransmit",
 271                 d->aoemajor, d->aoeminor, f->tag, jiffies, n);
 272         aoechr_error(buf);
 273
 274         skb = f->skb;
 275         h = (struct aoe_hdr *) skb->mac.raw;
 276         ah = (struct aoe_atahdr *) (h+1);
 277         f->tag = n;
 278         h->tag = cpu_to_be32(n);
 279         memcpy(h->dst, d->addr, sizeof h->dst);
 280         memcpy(h->src, d->ifp->dev_addr, sizeof h->src);
 281
 282         n = DEFAULTBCNT / 512;
 283         if (ah->scnt > n) {
 284                 ah->scnt = n;
 285                 if (ah->aflags & AOEAFL_WRITE)
 286                         skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
 287                                 offset_in_page(f->bufaddr), DEFAULTBCNT);
 288                 if (++d->lostjumbo > (d->nframes << 1))
 289                 if (d->maxbcnt != DEFAULTBCNT) {
 290                         printk(KERN_INFO "aoe: rexmit: too many lost jumbo.  "
 291                                 "dropping back to 1KB frames.\n");
 292                         d->maxbcnt = DEFAULTBCNT;
 293                         d->flags |= DEVFL_MAXBCNT;
 294                 }
 295         }
 296
 297         skb->dev = d->ifp;
 298         skb_get(skb);
 299         skb->next = NULL;
 300         if (d->sendq_hd)
 301                 d->sendq_tl->next = skb;
 302         else
 303                 d->sendq_hd = skb;
 304         d->sendq_tl = skb;
 305 }
 306
 307 static int
 308 tsince(int tag)
 309 {
 310         int n;
 311
 312         n = jiffies & 0xffff;
 313         n -= tag & 0xffff;
 314         if (n < 0)
 315                 n += 1<<16;
 316         return n;
 317 }
 318
 319 static void
 320 rexmit_timer(ulong vp)
 321 {
 322         struct aoedev *d;
 323         struct frame *f, *e;
 324         struct sk_buff *sl;
 325         register long timeout;
 326         ulong flags, n;
 327
 328         d = (struct aoedev *) vp;
 329         sl = NULL;
 330
 331         /* timeout is always ~150% of the moving average */
 332         timeout = d->rttavg;
 333         timeout += timeout >> 1;
 334
 335         spin_lock_irqsave(&d->lock, flags);
 336
 337         if (d->flags & DEVFL_TKILL) {
 338                 spin_unlock_irqrestore(&d->lock, flags);
 339                 return;
 340         }
 341         f = d->frames;
 342         e = f + d->nframes;
 343         for (; f<e; f++) {
 344                 if (f->tag != FREETAG && tsince(f->tag) >= timeout) {
 345                         n = f->waited += timeout;
 346                         n /= HZ;
 347                         if (n > MAXWAIT) { /* waited too long.  device failure. */
 348                                 aoedev_downdev(d);
 349                                 break;
 350                         }
 351                         rexmit(d, f);
 352                 }
 353         }
 354
 355         sl = d->sendq_hd;
 356         d->sendq_hd = d->sendq_tl = NULL;
 357         if (sl) {
 358                 n = d->rttavg <<= 1;
 359                 if (n > MAXTIMER)
 360                         d->rttavg = MAXTIMER;
 361         }
 362
 363         d->timer.expires = jiffies + TIMERTICK;
 364         add_timer(&d->timer);
 365
 366         spin_unlock_irqrestore(&d->lock, flags);
 367
 368         aoenet_xmit(sl);
 369 }
 370
 371 /* this function performs work that has been deferred until sleeping is OK
 372  */
 373 void
 374 aoecmd_sleepwork(void *vp)
 375 {
 376         struct aoedev *d = (struct aoedev *) vp;
 377
 378         if (d->flags & DEVFL_GDALLOC)
 379                 aoeblk_gdalloc(d);
 380
 381         if (d->flags & DEVFL_NEWSIZE) {
 382                 struct block_device *bd;
 383                 unsigned long flags;
 384                 u64 ssize;
 385
 386                 ssize = d->gd->capacity;
 387                 bd = bdget_disk(d->gd, 0);
 388
 389                 if (bd) {
 390                         mutex_lock(&bd->bd_inode->i_mutex);
 391                         i_size_write(bd->bd_inode, (loff_t)ssize<<9);
 392                         mutex_unlock(&bd->bd_inode->i_mutex);
 393                         bdput(bd);
 394                 }
 395                 spin_lock_irqsave(&d->lock, flags);
 396                 d->flags |= DEVFL_UP;
 397                 d->flags &= ~DEVFL_NEWSIZE;
 398                 spin_unlock_irqrestore(&d->lock, flags);
 399         }
 400 }
 401
 402 static void
 403 ataid_complete(struct aoedev *d, unsigned char *id)
 404 {
 405         u64 ssize;
 406         u16 n;
 407
 408         /* word 83: command set supported */
 409         n = le16_to_cpu(get_unaligned((__le16 *) &id[83<<1]));
 410
 411         /* word 86: command set/feature enabled */
 412         n |= le16_to_cpu(get_unaligned((__le16 *) &id[86<<1]));
 413
 414         if (n & (1<<10)) {      /* bit 10: LBA 48 */
 415                 d->flags |= DEVFL_EXT;
 416
 417                 /* word 100: number lba48 sectors */
 418                 ssize = le64_to_cpu(get_unaligned((__le64 *) &id[100<<1]));
 419
 420                 /* set as in ide-disk.c:init_idedisk_capacity */
 421                 d->geo.cylinders = ssize;
 422                 d->geo.cylinders /= (255 * 63);
 423                 d->geo.heads = 255;
 424                 d->geo.sectors = 63;
 425         } else {
 426                 d->flags &= ~DEVFL_EXT;
 427
 428                 /* number lba28 sectors */
 429                 ssize = le32_to_cpu(get_unaligned((__le32 *) &id[60<<1]));
 430
 431                 /* NOTE: obsolete in ATA 6 */
 432                 d->geo.cylinders = le16_to_cpu(get_unaligned((__le16 *) &id[54<<1]));
 433                 d->geo.heads = le16_to_cpu(get_unaligned((__le16 *) &id[55<<1]));
 434                 d->geo.sectors = le16_to_cpu(get_unaligned((__le16 *) &id[56<<1]));
 435         }
 436
 437         if (d->ssize != ssize)
 438                 printk(KERN_INFO "aoe: %012llx e%lu.%lu v%04x has %llu "
 439                         "sectors\n", (unsigned long long)mac_addr(d->addr),
 440                         d->aoemajor, d->aoeminor,
 441                         d->fw_ver, (long long)ssize);
 442         d->ssize = ssize;
 443         d->geo.start = 0;
 444         if (d->gd != NULL) {
 445                 d->gd->capacity = ssize;
 446                 d->flags |= DEVFL_NEWSIZE;
 447         } else {
 448                 if (d->flags & DEVFL_GDALLOC) {
 449                         printk(KERN_INFO "aoe: %s: %s e%lu.%lu, %s\n",
 450                                __FUNCTION__,
 451                                "can't schedule work for",
 452                                d->aoemajor, d->aoeminor,
 453                                "it's already on! (This really shouldn't happen).\n");
 454                         return;
 455                 }
 456                 d->flags |= DEVFL_GDALLOC;
 457         }
 458         schedule_work(&d->work);
 459 }
 460
 461 static void
 462 calc_rttavg(struct aoedev *d, int rtt)
 463 {
 464         register long n;
 465
 466         n = rtt;
 467         if (n < MINTIMER)
 468                 n = MINTIMER;
 469         else if (n > MAXTIMER)
 470                 n = MAXTIMER;
 471
 472         /* g == .25; cf. Congestion Avoidance and Control, Jacobson & Karels; 1988 */
 473         n -= d->rttavg;
 474         d->rttavg += n >> 2;
 475 }
 476
 477 void
 478 aoecmd_ata_rsp(struct sk_buff *skb)
 479 {
 480         struct aoedev *d;
 481         struct aoe_hdr *hin;
 482         struct aoe_atahdr *ahin, *ahout;
 483         struct frame *f;
 484         struct buf *buf;
 485         struct sk_buff *sl;
 486         register long n;
 487         ulong flags;
 488         char ebuf[128];
 489         u16 aoemajor;
 490
 491         hin = (struct aoe_hdr *) skb->mac.raw;
 492         aoemajor = be16_to_cpu(hin->major);
 493         d = aoedev_by_aoeaddr(aoemajor, hin->minor);
 494         if (d == NULL) {
 495                 snprintf(ebuf, sizeof ebuf, "aoecmd_ata_rsp: ata response "
 496                         "for unknown device %d.%d\n",
 497                          aoemajor, hin->minor);
 498                 aoechr_error(ebuf);
 499                 return;
 500         }
 501
 502         spin_lock_irqsave(&d->lock, flags);
 503
 504         f = getframe(d, be32_to_cpu(hin->tag));
 505         if (f == NULL) {
 506                 spin_unlock_irqrestore(&d->lock, flags);
 507                 snprintf(ebuf, sizeof ebuf,
 508                         "%15s e%d.%d    tag=%08x@%08lx\n",
 509                         "unexpected rsp",
 510                         be16_to_cpu(hin->major),
 511                         hin->minor,
 512                         be32_to_cpu(hin->tag),
 513                         jiffies);
 514                 aoechr_error(ebuf);
 515                 return;
 516         }
 517
 518         calc_rttavg(d, tsince(f->tag));
 519
 520         ahin = (struct aoe_atahdr *) (hin+1);
 521         ahout = (struct aoe_atahdr *) (f->skb->mac.raw + sizeof(struct aoe_hdr));
 522         buf = f->buf;
 523
 524         if (ahout->cmdstat == WIN_IDENTIFY)
 525                 d->flags &= ~DEVFL_PAUSE;
 526         if (ahin->cmdstat & 0xa9) {     /* these bits cleared on success */
 527                 printk(KERN_CRIT "aoe: aoecmd_ata_rsp: ata error cmd=%2.2Xh "
 528                         "stat=%2.2Xh from e%ld.%ld\n",
 529                         ahout->cmdstat, ahin->cmdstat,
 530                         d->aoemajor, d->aoeminor);
 531                 if (buf)
 532                         buf->flags |= BUFFL_FAIL;
 533         } else {
 534                 n = ahout->scnt << 9;
 535                 switch (ahout->cmdstat) {
 536                 case WIN_READ:
 537                 case WIN_READ_EXT:
 538                         if (skb->len - sizeof *hin - sizeof *ahin < n) {
 539                                 printk(KERN_CRIT "aoe: aoecmd_ata_rsp: runt "
 540                                         "ata data size in read.  skb->len=%d\n",
 541                                         skb->len);
 542                                 /* fail frame f?  just returning will rexmit. */
 543                                 spin_unlock_irqrestore(&d->lock, flags);
 544                                 return;
 545                         }
 546                         memcpy(f->bufaddr, ahin+1, n);
 547                 case WIN_WRITE:
 548                 case WIN_WRITE_EXT:
 549                         if (f->bcnt -= n) {
 550                                 f->bufaddr += n;
 551                                 put_lba(ahout, f->lba += ahout->scnt);
 552                                 n = f->bcnt > DEFAULTBCNT ? DEFAULTBCNT : f->bcnt;
 553                                 ahout->scnt = n >> 9;
 554                                 if (ahout->aflags & AOEAFL_WRITE)
 555                                         skb_fill_page_desc(f->skb, 0, virt_to_page(f->bufaddr),
 556                                                 offset_in_page(f->bufaddr), n);
 557                                 skb_get(f->skb);
 558                                 f->skb->next = NULL;
 559                                 spin_unlock_irqrestore(&d->lock, flags);
 560                                 aoenet_xmit(f->skb);
 561                                 return;
 562                         }
 563                         if (n > DEFAULTBCNT)
 564                                 d->lostjumbo = 0;
 565                         break;
 566                 case WIN_IDENTIFY:
 567                         if (skb->len - sizeof *hin - sizeof *ahin < 512) {
 568                                 printk(KERN_INFO "aoe: aoecmd_ata_rsp: runt data size "
 569                                         "in ataid.  skb->len=%d\n", skb->len);
 570                                 spin_unlock_irqrestore(&d->lock, flags);
 571                                 return;
 572                         }
 573                         ataid_complete(d, (char *) (ahin+1));
 574                         break;
 575                 default:
 576                         printk(KERN_INFO "aoe: aoecmd_ata_rsp: unrecognized "
 577                                "outbound ata command %2.2Xh for %d.%d\n",
 578                                ahout->cmdstat,
 579                                be16_to_cpu(hin->major),
 580                                hin->minor);
 581                 }
 582         }
 583
 584         if (buf) {
 585                 buf->nframesout -= 1;
 586                 if (buf->nframesout == 0 && buf->resid == 0) {
 587                         unsigned long duration = jiffies - buf->start_time;
 588                         unsigned long n_sect = buf->bio->bi_size >> 9;
 589                         struct gendisk *disk = d->gd;
 590                         const int rw = bio_data_dir(buf->bio);
 591
 592                         disk_stat_inc(disk, ios[rw]);
 593                         disk_stat_add(disk, ticks[rw], duration);
 594                         disk_stat_add(disk, sectors[rw], n_sect);
 595                         disk_stat_add(disk, io_ticks, duration);
 596                         n = (buf->flags & BUFFL_FAIL) ? -EIO : 0;
 597                         bio_endio(buf->bio, buf->bio->bi_size, n);
 598                         mempool_free(buf, d->bufpool);
 599                 }
 600         }
 601
 602         f->buf = NULL;
 603         f->tag = FREETAG;
 604
 605         aoecmd_work(d);
 606         sl = d->sendq_hd;
 607         d->sendq_hd = d->sendq_tl = NULL;
 608
 609         spin_unlock_irqrestore(&d->lock, flags);
 610         aoenet_xmit(sl);
 611 }
 612
 613 void
 614 aoecmd_cfg(ushort aoemajor, unsigned char aoeminor)
 615 {
 616         struct sk_buff *sl;
 617
 618         sl = aoecmd_cfg_pkts(aoemajor, aoeminor, NULL);
 619
 620         aoenet_xmit(sl);
 621 }
 622
 623 /*
 624  * Since we only call this in one place (and it only prepares one frame)
 625  * we just return the skb.  Usually we'd chain it up to the aoedev sendq.
 626  */
 627 static struct sk_buff *
 628 aoecmd_ata_id(struct aoedev *d)
 629 {
 630         struct aoe_hdr *h;
 631         struct aoe_atahdr *ah;
 632         struct frame *f;
 633         struct sk_buff *skb;
 634
 635         f = getframe(d, FREETAG);
 636         if (f == NULL) {
 637                 printk(KERN_CRIT "aoe: aoecmd_ata_id: can't get a frame.  "
 638                         "This shouldn't happen.\n");
 639                 return NULL;
 640         }
 641
 642         /* initialize the headers & frame */
 643         skb = f->skb;
 644         h = (struct aoe_hdr *) skb->mac.raw;
 645         ah = (struct aoe_atahdr *) (h+1);
 646         skb->len = sizeof *h + sizeof *ah;
 647         memset(h, 0, skb->len);
 648         f->tag = aoehdr_atainit(d, h);
 649         f->waited = 0;
 650
 651         /* set up ata header */
 652         ah->scnt = 1;
 653         ah->cmdstat = WIN_IDENTIFY;
 654         ah->lba3 = 0xa0;
 655
 656         skb->dev = d->ifp;
 657         skb_get(skb);
 658
 659         d->rttavg = MAXTIMER;
 660         d->timer.function = rexmit_timer;
 661
 662         return skb;
 663 }
 664
 665 void
 666 aoecmd_cfg_rsp(struct sk_buff *skb)
 667 {
 668         struct aoedev *d;
 669         struct aoe_hdr *h;
 670         struct aoe_cfghdr *ch;
 671         ulong flags, sysminor, aoemajor;
 672         struct sk_buff *sl;
 673         enum { MAXFRAMES = 16 };
 674         u16 n;
 675
 676         h = (struct aoe_hdr *) skb->mac.raw;
 677         ch = (struct aoe_cfghdr *) (h+1);
 678
 679         /*
 680          * Enough people have their dip switches set backwards to
 681          * warrant a loud message for this special case.
 682          */
 683         aoemajor = be16_to_cpu(h->major);
 684         if (aoemajor == 0xfff) {
 685                 printk(KERN_CRIT "aoe: aoecmd_cfg_rsp: Warning: shelf "
 686                         "address is all ones.  Check shelf dip switches\n");
 687                 return;
 688         }
 689
 690         sysminor = SYSMINOR(aoemajor, h->minor);
 691         if (sysminor * AOE_PARTITIONS + AOE_PARTITIONS > MINORMASK) {
 692                 printk(KERN_INFO
 693                         "aoe: e%ld.%d: minor number too large\n",
 694                         aoemajor, (int) h->minor);
 695                 return;
 696         }
 697
 698         n = be16_to_cpu(ch->bufcnt);
 699         if (n > MAXFRAMES)      /* keep it reasonable */
 700                 n = MAXFRAMES;
 701
 702         d = aoedev_by_sysminor_m(sysminor, n);
 703         if (d == NULL) {
 704                 printk(KERN_INFO "aoe: aoecmd_cfg_rsp: device sysminor_m failure\n");
 705                 return;
 706         }
 707
 708         spin_lock_irqsave(&d->lock, flags);
 709
 710         /* permit device to migrate mac and network interface */
 711         d->ifp = skb->dev;
 712         memcpy(d->addr, h->src, sizeof d->addr);
 713         if (!(d->flags & DEVFL_MAXBCNT)) {
 714                 n = d->ifp->mtu;
 715                 n -= sizeof (struct aoe_hdr) + sizeof (struct aoe_atahdr);
 716                 n /= 512;
 717                 if (n > ch->scnt)
 718                         n = ch->scnt;
 719                 d->maxbcnt = n ? n * 512 : DEFAULTBCNT;
 720         }
 721
 722         /* don't change users' perspective */
 723         if (d->nopen && !(d->flags & DEVFL_PAUSE)) {
 724                 spin_unlock_irqrestore(&d->lock, flags);
 725                 return;
 726         }
 727         d->flags |= DEVFL_PAUSE;        /* force pause */
 728         d->fw_ver = be16_to_cpu(ch->fwver);
 729
 730         /* check for already outstanding ataid */
 731         sl = aoedev_isbusy(d) == 0 ? aoecmd_ata_id(d) : NULL;
 732
 733         spin_unlock_irqrestore(&d->lock, flags);
 734
 735         aoenet_xmit(sl);
 736 }
 737