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ub.c

/*
 * The low performance USB storage driver (ub).
 *
 * Copyright (c) 1999, 2000 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
 * Copyright (C) 2004 Pete Zaitcev (zaitcev@yahoo.com)
 *
 * This work is a part of Linux kernel, is derived from it,
 * and is not licensed separately. See file COPYING for details.
 *
 * TODO (sorted by decreasing priority)
 *  -- set readonly flag for CDs, set removable flag for CF readers
 *  -- do inquiry and verify we got a disk and not a tape (for LUN mismatch)
 *  -- verify the 13 conditions and do bulk resets
 *  -- highmem
 *  -- move top_sense and work_bcs into separate allocations (if they survive)
 *     for cache purists and esoteric architectures.
 *  -- Allocate structure for LUN 0 before the first ub_sync_tur, avoid NULL. ?
 *  -- prune comments, they are too volumnous
 *  -- Resove XXX's
 *  -- CLEAR, CLR2STS, CLRRS seem to be ripe for refactoring.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb_usual.h>
#include <linux/blkdev.h>
#include <linux/timer.h>
#include <scsi/scsi.h>

#define DRV_NAME "ub"

#define UB_MAJOR 180

/*
 * The command state machine is the key model for understanding of this driver.
 *
 * The general rule is that all transitions are done towards the bottom
 * of the diagram, thus preventing any loops.
 *
 * An exception to that is how the STAT state is handled. A counter allows it
 * to be re-entered along the path marked with [C].
 *
 *       +--------+
 *       ! INIT   !
 *       +--------+
 *           !
 *        ub_scsi_cmd_start fails ->--------------------------------------\
 *           !                                                            !
 *           V                                                            !
 *       +--------+                                                       !
 *       ! CMD    !                                                       !
 *       +--------+                                                       !
 *           !                                            +--------+      !
 *         was -EPIPE -->-------------------------------->! CLEAR  !      !
 *           !                                            +--------+      !
 *           !                                                !           !
 *         was error -->------------------------------------- ! --------->\
 *           !                                                !           !
 *  /--<-- cmd->dir == NONE ?                                 !           !
 *  !        !                                                !           !
 *  !        V                                                !           !
 *  !    +--------+                                           !           !
 *  !    ! DATA   !                                           !           !
 *  !    +--------+                                           !           !
 *  !        !                           +---------+          !           !
 *  !      was -EPIPE -->--------------->! CLR2STS !          !           !
 *  !        !                           +---------+          !           !
 *  !        !                                !               !           !
 *  !        !                              was error -->---- ! --------->\
 *  !      was error -->--------------------- ! ------------- ! --------->\
 *  !        !                                !               !           !
 *  !        V                                !               !           !
 *  \--->+--------+                           !               !           !
 *       ! STAT   !<--------------------------/               !           !
 *  /--->+--------+                                           !           !
 *  !        !                                                !           !
 * [C]     was -EPIPE -->-----------\                         !           !
 *  !        !                      !                         !           !
 *  +<---- len == 0                 !                         !           !
 *  !        !                      !                         !           !
 *  !      was error -->--------------------------------------!---------->\
 *  !        !                      !                         !           !
 *  +<---- bad CSW                  !                         !           !
 *  +<---- bad tag                  !                         !           !
 *  !        !                      V                         !           !
 *  !        !                 +--------+                     !           !
 *  !        !                 ! CLRRS  !                     !           !
 *  !        !                 +--------+                     !           !
 *  !        !                      !                         !           !
 *  \------- ! --------------------[C]--------\               !           !
 *           !                                !               !           !
 *         cmd->error---\                +--------+           !           !
 *           !          +--------------->! SENSE  !<----------/           !
 *         STAT_FAIL----/                +--------+                       !
 *           !                                !                           V
 *           !                                V                      +--------+
 *           \--------------------------------\--------------------->! DONE   !
 *                                                                   +--------+
 */

/*
 * This many LUNs per USB device.
 * Every one of them takes a host, see UB_MAX_HOSTS.
 */
#define UB_MAX_LUNS   9

/*
 */

#define UB_PARTS_PER_LUN      8

#define UB_MAX_CDB_SIZE      16           /* Corresponds to Bulk */

#define UB_SENSE_SIZE  18

/*
 */

/* command block wrapper */
struct bulk_cb_wrap {
      __le32      Signature;        /* contains 'USBC' */
      u32   Tag;              /* unique per command id */
      __le32      DataTransferLength;     /* size of data */
      u8    Flags;                  /* direction in bit 0 */
      u8    Lun;              /* LUN */
      u8    Length;                 /* of of the CDB */
      u8    CDB[UB_MAX_CDB_SIZE];   /* max command */
};

#define US_BULK_CB_WRAP_LEN   31
#define US_BULK_CB_SIGN       0x43425355  /*spells out USBC */
#define US_BULK_FLAG_IN       1
#define US_BULK_FLAG_OUT      0

/* command status wrapper */
struct bulk_cs_wrap {
      __le32      Signature;        /* should = 'USBS' */
      u32   Tag;              /* same as original command */
      __le32      Residue;          /* amount not transferred */
      u8    Status;                 /* see below */
};

#define US_BULK_CS_WRAP_LEN   13
#define US_BULK_CS_SIGN       0x53425355  /* spells out 'USBS' */
#define US_BULK_STAT_OK       0
#define US_BULK_STAT_FAIL     1
#define US_BULK_STAT_PHASE    2

/* bulk-only class specific requests */
#define US_BULK_RESET_REQUEST 0xff
#define US_BULK_GET_MAX_LUN   0xfe

/*
 */
struct ub_dev;

#define UB_MAX_REQ_SG   9     /* cdrecord requires 32KB and maybe a header */
#define UB_MAX_SECTORS 64

/*
 * A second is more than enough for a 32K transfer (UB_MAX_SECTORS)
 * even if a webcam hogs the bus, but some devices need time to spin up.
 */
#define UB_URB_TIMEOUT  (HZ*2)
#define UB_DATA_TIMEOUT (HZ*5)      /* ZIP does spin-ups in the data phase */
#define UB_STAT_TIMEOUT (HZ*5)      /* Same spinups and eject for a dataless cmd. */
#define UB_CTRL_TIMEOUT (HZ/2)      /* 500ms ought to be enough to clear a stall */

/*
 * An instance of a SCSI command in transit.
 */
#define UB_DIR_NONE     0
#define UB_DIR_READ     1
#define UB_DIR_ILLEGAL2 2
#define UB_DIR_WRITE    3

#define UB_DIR_CHAR(c)  (((c)==UB_DIR_WRITE)? 'w': \
                   (((c)==UB_DIR_READ)? 'r': 'n'))

enum ub_scsi_cmd_state {
      UB_CMDST_INIT,                /* Initial state */
      UB_CMDST_CMD,                 /* Command submitted */
      UB_CMDST_DATA,                /* Data phase */
      UB_CMDST_CLR2STS,       /* Clearing before requesting status */
      UB_CMDST_STAT,                /* Status phase */
      UB_CMDST_CLEAR,               /* Clearing a stall (halt, actually) */
      UB_CMDST_CLRRS,               /* Clearing before retrying status */
      UB_CMDST_SENSE,               /* Sending Request Sense */
      UB_CMDST_DONE                 /* Final state */
};

struct ub_scsi_cmd {
      unsigned char cdb[UB_MAX_CDB_SIZE];
      unsigned char cdb_len;

      unsigned char dir;            /* 0 - none, 1 - read, 3 - write. */
      enum ub_scsi_cmd_state state;
      unsigned int tag;
      struct ub_scsi_cmd *next;

      int error;              /* Return code - valid upon done */
      unsigned int act_len;         /* Return size */
      unsigned char key, asc, ascq; /* May be valid if error==-EIO */

      int stat_count;               /* Retries getting status. */

      unsigned int len;       /* Requested length */
      unsigned int current_sg;
      unsigned int nsg;       /* sgv[nsg] */
      struct scatterlist sgv[UB_MAX_REQ_SG];

      struct ub_lun *lun;
      void (*done)(struct ub_dev *, struct ub_scsi_cmd *);
      void *back;
};

struct ub_request {
      struct request *rq;
      unsigned int current_try;
      unsigned int nsg;       /* sgv[nsg] */
      struct scatterlist sgv[UB_MAX_REQ_SG];
};

/*
 */
struct ub_capacity {
      unsigned long nsec;           /* Linux size - 512 byte sectors */
      unsigned int bsize;           /* Linux hardsect_size */
      unsigned int bshift;          /* Shift between 512 and hard sects */
};

/*
 * This is a direct take-off from linux/include/completion.h
 * The difference is that I do not wait on this thing, just poll.
 * When I want to wait (ub_probe), I just use the stock completion.
 *
 * Note that INIT_COMPLETION takes no lock. It is correct. But why
 * in the bloody hell that thing takes struct instead of pointer to struct
 * is quite beyond me. I just copied it from the stock completion.
 */
struct ub_completion {
      unsigned int done;
      spinlock_t lock;
};

static inline void ub_init_completion(struct ub_completion *x)
{
      x->done = 0;
      spin_lock_init(&x->lock);
}

#define UB_INIT_COMPLETION(x) ((x).done = 0)

static void ub_complete(struct ub_completion *x)
{
      unsigned long flags;

      spin_lock_irqsave(&x->lock, flags);
      x->done++;
      spin_unlock_irqrestore(&x->lock, flags);
}

static int ub_is_completed(struct ub_completion *x)
{
      unsigned long flags;
      int ret;

      spin_lock_irqsave(&x->lock, flags);
      ret = x->done;
      spin_unlock_irqrestore(&x->lock, flags);
      return ret;
}

/*
 */
struct ub_scsi_cmd_queue {
      int qlen, qmax;
      struct ub_scsi_cmd *head, *tail;
};

/*
 * The block device instance (one per LUN).
 */
struct ub_lun {
      struct ub_dev *udev;
      struct list_head link;
      struct gendisk *disk;
      int id;                       /* Host index */
      int num;                /* LUN number */
      char name[16];

      int changed;                  /* Media was changed */
      int removable;
      int readonly;

      struct ub_request urq;

      /* Use Ingo's mempool if or when we have more than one command. */
      /*
       * Currently we never need more than one command for the whole device.
       * However, giving every LUN a command is a cheap and automatic way
       * to enforce fairness between them.
       */
      int cmda[1];
      struct ub_scsi_cmd cmdv[1];

      struct ub_capacity capacity; 
};

/*
 * The USB device instance.
 */
struct ub_dev {
      spinlock_t *lock;
      atomic_t poison;        /* The USB device is disconnected */
      int openc;              /* protected by ub_lock! */
                              /* kref is too implicit for our taste */
      int reset;              /* Reset is running */
      unsigned int tagcnt;
      char name[12];
      struct usb_device *dev;
      struct usb_interface *intf;

      struct list_head luns;

      unsigned int send_bulk_pipe;  /* cached pipe values */
      unsigned int recv_bulk_pipe;
      unsigned int send_ctrl_pipe;
      unsigned int recv_ctrl_pipe;

      struct tasklet_struct tasklet;

      struct ub_scsi_cmd_queue cmd_queue;
      struct ub_scsi_cmd top_rqs_cmd;     /* REQUEST SENSE */
      unsigned char top_sense[UB_SENSE_SIZE];

      struct ub_completion work_done;
      struct urb work_urb;
      struct timer_list work_timer;
      int last_pipe;                /* What might need clearing */
      __le32 signature;       /* Learned signature */
      struct bulk_cb_wrap work_bcb;
      struct bulk_cs_wrap work_bcs;
      struct usb_ctrlrequest work_cr;

      struct work_struct reset_work;
      wait_queue_head_t reset_wait;

      int sg_stat[6];
};

/*
 */
static void ub_cleanup(struct ub_dev *sc);
static int ub_request_fn_1(struct ub_lun *lun, struct request *rq);
static void ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_scsi_cmd *cmd, struct ub_request *urq);
static void ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_scsi_cmd *cmd, struct ub_request *urq);
static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_end_rq(struct request *rq, int uptodate);
static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_request *urq, struct ub_scsi_cmd *cmd);
static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_urb_complete(struct urb *urb, struct pt_regs *pt);
static void ub_scsi_action(unsigned long _dev);
static void ub_scsi_dispatch(struct ub_dev *sc);
static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc);
static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
    int stalled_pipe);
static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd);
static void ub_reset_enter(struct ub_dev *sc, int try);
static void ub_reset_task(void *arg);
static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun);
static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_capacity *ret);
static int ub_sync_reset(struct ub_dev *sc);
static int ub_probe_clear_stall(struct ub_dev *sc, int stalled_pipe);
static int ub_probe_lun(struct ub_dev *sc, int lnum);

/*
 */
#ifdef CONFIG_USB_LIBUSUAL

#define ub_usb_ids  storage_usb_ids
#else

static struct usb_device_id ub_usb_ids[] = {
      { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, US_SC_SCSI, US_PR_BULK) },
      { }
};

MODULE_DEVICE_TABLE(usb, ub_usb_ids);
#endif /* CONFIG_USB_LIBUSUAL */

/*
 * Find me a way to identify "next free minor" for add_disk(),
 * and the array disappears the next day. However, the number of
 * hosts has something to do with the naming and /proc/partitions.
 * This has to be thought out in detail before changing.
 * If UB_MAX_HOST was 1000, we'd use a bitmap. Or a better data structure.
 */
#define UB_MAX_HOSTS  26
static char ub_hostv[UB_MAX_HOSTS];

#define UB_QLOCK_NUM 5
static spinlock_t ub_qlockv[UB_QLOCK_NUM];
static int ub_qlock_next = 0;

static DEFINE_SPINLOCK(ub_lock);    /* Locks globals and ->openc */

/*
 * The id allocator.
 *
 * This also stores the host for indexing by minor, which is somewhat dirty.
 */
static int ub_id_get(void)
{
      unsigned long flags;
      int i;

      spin_lock_irqsave(&ub_lock, flags);
      for (i = 0; i < UB_MAX_HOSTS; i++) {
            if (ub_hostv[i] == 0) {
                  ub_hostv[i] = 1;
                  spin_unlock_irqrestore(&ub_lock, flags);
                  return i;
            }
      }
      spin_unlock_irqrestore(&ub_lock, flags);
      return -1;
}

static void ub_id_put(int id)
{
      unsigned long flags;

      if (id < 0 || id >= UB_MAX_HOSTS) {
            printk(KERN_ERR DRV_NAME ": bad host ID %d\n", id);
            return;
      }

      spin_lock_irqsave(&ub_lock, flags);
      if (ub_hostv[id] == 0) {
            spin_unlock_irqrestore(&ub_lock, flags);
            printk(KERN_ERR DRV_NAME ": freeing free host ID %d\n", id);
            return;
      }
      ub_hostv[id] = 0;
      spin_unlock_irqrestore(&ub_lock, flags);
}

/*
 * This is necessitated by the fact that blk_cleanup_queue does not
 * necesserily destroy the queue. Instead, it may merely decrease q->refcnt.
 * Since our blk_init_queue() passes a spinlock common with ub_dev,
 * we have life time issues when ub_cleanup frees ub_dev.
 */
static spinlock_t *ub_next_lock(void)
{
      unsigned long flags;
      spinlock_t *ret;

      spin_lock_irqsave(&ub_lock, flags);
      ret = &ub_qlockv[ub_qlock_next];
      ub_qlock_next = (ub_qlock_next + 1) % UB_QLOCK_NUM;
      spin_unlock_irqrestore(&ub_lock, flags);
      return ret;
}

/*
 * Downcount for deallocation. This rides on two assumptions:
 *  - once something is poisoned, its refcount cannot grow
 *  - opens cannot happen at this time (del_gendisk was done)
 * If the above is true, we can drop the lock, which we need for
 * blk_cleanup_queue(): the silly thing may attempt to sleep.
 * [Actually, it never needs to sleep for us, but it calls might_sleep()]
 */
static void ub_put(struct ub_dev *sc)
{
      unsigned long flags;

      spin_lock_irqsave(&ub_lock, flags);
      --sc->openc;
      if (sc->openc == 0 && atomic_read(&sc->poison)) {
            spin_unlock_irqrestore(&ub_lock, flags);
            ub_cleanup(sc);
      } else {
            spin_unlock_irqrestore(&ub_lock, flags);
      }
}

/*
 * Final cleanup and deallocation.
 */
static void ub_cleanup(struct ub_dev *sc)
{
      struct list_head *p;
      struct ub_lun *lun;
      request_queue_t *q;

      while (!list_empty(&sc->luns)) {
            p = sc->luns.next;
            lun = list_entry(p, struct ub_lun, link);
            list_del(p);

            /* I don't think queue can be NULL. But... Stolen from sx8.c */
            if ((q = lun->disk->queue) != NULL)
                  blk_cleanup_queue(q);
            /*
             * If we zero disk->private_data BEFORE put_disk, we have
             * to check for NULL all over the place in open, release,
             * check_media and revalidate, because the block level
             * semaphore is well inside the put_disk.
             * But we cannot zero after the call, because *disk is gone.
             * The sd.c is blatantly racy in this area.
             */
            /* disk->private_data = NULL; */
            put_disk(lun->disk);
            lun->disk = NULL;

            ub_id_put(lun->id);
            kfree(lun);
      }

      usb_set_intfdata(sc->intf, NULL);
      usb_put_intf(sc->intf);
      usb_put_dev(sc->dev);
      kfree(sc);
}

/*
 * The "command allocator".
 */
static struct ub_scsi_cmd *ub_get_cmd(struct ub_lun *lun)
{
      struct ub_scsi_cmd *ret;

      if (lun->cmda[0])
            return NULL;
      ret = &lun->cmdv[0];
      lun->cmda[0] = 1;
      return ret;
}

static void ub_put_cmd(struct ub_lun *lun, struct ub_scsi_cmd *cmd)
{
      if (cmd != &lun->cmdv[0]) {
            printk(KERN_WARNING "%s: releasing a foreign cmd %p\n",
                lun->name, cmd);
            return;
      }
      if (!lun->cmda[0]) {
            printk(KERN_WARNING "%s: releasing a free cmd\n", lun->name);
            return;
      }
      lun->cmda[0] = 0;
}

/*
 * The command queue.
 */
static void ub_cmdq_add(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct ub_scsi_cmd_queue *t = &sc->cmd_queue;

      if (t->qlen++ == 0) {
            t->head = cmd;
            t->tail = cmd;
      } else {
            t->tail->next = cmd;
            t->tail = cmd;
      }

      if (t->qlen > t->qmax)
            t->qmax = t->qlen;
}

static void ub_cmdq_insert(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct ub_scsi_cmd_queue *t = &sc->cmd_queue;

      if (t->qlen++ == 0) {
            t->head = cmd;
            t->tail = cmd;
      } else {
            cmd->next = t->head;
            t->head = cmd;
      }

      if (t->qlen > t->qmax)
            t->qmax = t->qlen;
}

static struct ub_scsi_cmd *ub_cmdq_pop(struct ub_dev *sc)
{
      struct ub_scsi_cmd_queue *t = &sc->cmd_queue;
      struct ub_scsi_cmd *cmd;

      if (t->qlen == 0)
            return NULL;
      if (--t->qlen == 0)
            t->tail = NULL;
      cmd = t->head;
      t->head = cmd->next;
      cmd->next = NULL;
      return cmd;
}

#define ub_cmdq_peek(sc)  ((sc)->cmd_queue.head)

/*
 * The request function is our main entry point
 */

static void ub_request_fn(request_queue_t *q)
{
      struct ub_lun *lun = q->queuedata;
      struct request *rq;

      while ((rq = elv_next_request(q)) != NULL) {
            if (ub_request_fn_1(lun, rq) != 0) {
                  blk_stop_queue(q);
                  break;
            }
      }
}

static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
{
      struct ub_dev *sc = lun->udev;
      struct ub_scsi_cmd *cmd;
      struct ub_request *urq;
      int n_elem;

      if (atomic_read(&sc->poison) || lun->changed) {
            blkdev_dequeue_request(rq);
            ub_end_rq(rq, 0);
            return 0;
      }

      if (lun->urq.rq != NULL)
            return -1;
      if ((cmd = ub_get_cmd(lun)) == NULL)
            return -1;
      memset(cmd, 0, sizeof(struct ub_scsi_cmd));

      blkdev_dequeue_request(rq);

      urq = &lun->urq;
      memset(urq, 0, sizeof(struct ub_request));
      urq->rq = rq;

      /*
       * get scatterlist from block layer
       */
      n_elem = blk_rq_map_sg(lun->disk->queue, rq, &urq->sgv[0]);
      if (n_elem < 0) {
            /* Impossible, because blk_rq_map_sg should not hit ENOMEM. */
            printk(KERN_INFO "%s: failed request map (%d)\n",
                lun->name, n_elem);
            goto drop;
      }
      if (n_elem > UB_MAX_REQ_SG) { /* Paranoia */
            printk(KERN_WARNING "%s: request with %d segments\n",
                lun->name, n_elem);
            goto drop;
      }
      urq->nsg = n_elem;
      sc->sg_stat[n_elem < 5 ? n_elem : 5]++;

      if (blk_pc_request(rq)) {
            ub_cmd_build_packet(sc, lun, cmd, urq);
      } else {
            ub_cmd_build_block(sc, lun, cmd, urq);
      }
      cmd->state = UB_CMDST_INIT;
      cmd->lun = lun;
      cmd->done = ub_rw_cmd_done;
      cmd->back = urq;

      cmd->tag = sc->tagcnt++;
      if (ub_submit_scsi(sc, cmd) != 0)
            goto drop;

      return 0;

drop:
      ub_put_cmd(lun, cmd);
      ub_end_rq(rq, 0);
      return 0;
}

static void ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_scsi_cmd *cmd, struct ub_request *urq)
{
      struct request *rq = urq->rq;
      unsigned int block, nblks;

      if (rq_data_dir(rq) == WRITE)
            cmd->dir = UB_DIR_WRITE;
      else
            cmd->dir = UB_DIR_READ;

      cmd->nsg = urq->nsg;
      memcpy(cmd->sgv, urq->sgv, sizeof(struct scatterlist) * cmd->nsg);

      /*
       * build the command
       *
       * The call to blk_queue_hardsect_size() guarantees that request
       * is aligned, but it is given in terms of 512 byte units, always.
       */
      block = rq->sector >> lun->capacity.bshift;
      nblks = rq->nr_sectors >> lun->capacity.bshift;

      cmd->cdb[0] = (cmd->dir == UB_DIR_READ)? READ_10: WRITE_10;
      /* 10-byte uses 4 bytes of LBA: 2147483648KB, 2097152MB, 2048GB */
      cmd->cdb[2] = block >> 24;
      cmd->cdb[3] = block >> 16;
      cmd->cdb[4] = block >> 8;
      cmd->cdb[5] = block;
      cmd->cdb[7] = nblks >> 8;
      cmd->cdb[8] = nblks;
      cmd->cdb_len = 10;

      cmd->len = rq->nr_sectors * 512;
}

static void ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_scsi_cmd *cmd, struct ub_request *urq)
{
      struct request *rq = urq->rq;

      if (rq->data_len == 0) {
            cmd->dir = UB_DIR_NONE;
      } else {
            if (rq_data_dir(rq) == WRITE)
                  cmd->dir = UB_DIR_WRITE;
            else
                  cmd->dir = UB_DIR_READ;
      }

      cmd->nsg = urq->nsg;
      memcpy(cmd->sgv, urq->sgv, sizeof(struct scatterlist) * cmd->nsg);

      memcpy(&cmd->cdb, rq->cmd, rq->cmd_len);
      cmd->cdb_len = rq->cmd_len;

      cmd->len = rq->data_len;
}

static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct ub_lun *lun = cmd->lun;
      struct ub_request *urq = cmd->back;
      struct request *rq;
      int uptodate;

      rq = urq->rq;

      if (cmd->error == 0) {
            uptodate = 1;

            if (blk_pc_request(rq)) {
                  if (cmd->act_len >= rq->data_len)
                        rq->data_len = 0;
                  else
                        rq->data_len -= cmd->act_len;
            }
      } else {
            uptodate = 0;

            if (blk_pc_request(rq)) {
                  /* UB_SENSE_SIZE is smaller than SCSI_SENSE_BUFFERSIZE */
                  memcpy(rq->sense, sc->top_sense, UB_SENSE_SIZE);
                  rq->sense_len = UB_SENSE_SIZE;
                  if (sc->top_sense[0] != 0)
                        rq->errors = SAM_STAT_CHECK_CONDITION;
                  else
                        rq->errors = DID_ERROR << 16;
            } else {
                  if (cmd->error == -EIO) {
                        if (ub_rw_cmd_retry(sc, lun, urq, cmd) == 0)
                              return;
                  }
            }
      }

      urq->rq = NULL;

      ub_put_cmd(lun, cmd);
      ub_end_rq(rq, uptodate);
      blk_start_queue(lun->disk->queue);
}

static void ub_end_rq(struct request *rq, int uptodate)
{
      end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
      end_that_request_last(rq, uptodate);
}

static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_request *urq, struct ub_scsi_cmd *cmd)
{

      if (atomic_read(&sc->poison))
            return -ENXIO;

      ub_reset_enter(sc, urq->current_try);

      if (urq->current_try >= 3)
            return -EIO;
      urq->current_try++;

      /* Remove this if anyone complains of flooding. */
      printk(KERN_DEBUG "%s: dir %c len/act %d/%d "
          "[sense %x %02x %02x] retry %d\n",
          sc->name, UB_DIR_CHAR(cmd->dir), cmd->len, cmd->act_len,
          cmd->key, cmd->asc, cmd->ascq, urq->current_try);

      memset(cmd, 0, sizeof(struct ub_scsi_cmd));
      ub_cmd_build_block(sc, lun, cmd, urq);

      cmd->state = UB_CMDST_INIT;
      cmd->lun = lun;
      cmd->done = ub_rw_cmd_done;
      cmd->back = urq;

      cmd->tag = sc->tagcnt++;

#if 0 /* Wasteful */
      return ub_submit_scsi(sc, cmd);
#else
      ub_cmdq_add(sc, cmd);
      return 0;
#endif
}

/*
 * Submit a regular SCSI operation (not an auto-sense).
 *
 * The Iron Law of Good Submit Routine is:
 * Zero return - callback is done, Nonzero return - callback is not done.
 * No exceptions.
 *
 * Host is assumed locked.
 */
static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{

      if (cmd->state != UB_CMDST_INIT ||
          (cmd->dir != UB_DIR_NONE && cmd->len == 0)) {
            return -EINVAL;
      }

      ub_cmdq_add(sc, cmd);
      /*
       * We can call ub_scsi_dispatch(sc) right away here, but it's a little
       * safer to jump to a tasklet, in case upper layers do something silly.
       */
      tasklet_schedule(&sc->tasklet);
      return 0;
}

/*
 * Submit the first URB for the queued command.
 * This function does not deal with queueing in any way.
 */
static int ub_scsi_cmd_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct bulk_cb_wrap *bcb;
      int rc;

      bcb = &sc->work_bcb;

      /*
       * ``If the allocation length is eighteen or greater, and a device
       * server returns less than eithteen bytes of data, the application
       * client should assume that the bytes not transferred would have been
       * zeroes had the device server returned those bytes.''
       *
       * We zero sense for all commands so that when a packet request
       * fails it does not return a stale sense.
       */
      memset(&sc->top_sense, 0, UB_SENSE_SIZE);

      /* set up the command wrapper */
      bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
      bcb->Tag = cmd->tag;          /* Endianness is not important */
      bcb->DataTransferLength = cpu_to_le32(cmd->len);
      bcb->Flags = (cmd->dir == UB_DIR_READ) ? 0x80 : 0;
      bcb->Lun = (cmd->lun != NULL) ? cmd->lun->num : 0;
      bcb->Length = cmd->cdb_len;

      /* copy the command payload */
      memcpy(bcb->CDB, cmd->cdb, UB_MAX_CDB_SIZE);

      UB_INIT_COMPLETION(sc->work_done);

      sc->last_pipe = sc->send_bulk_pipe;
      usb_fill_bulk_urb(&sc->work_urb, sc->dev, sc->send_bulk_pipe,
          bcb, US_BULK_CB_WRAP_LEN, ub_urb_complete, sc);

      /* Fill what we shouldn't be filling, because usb-storage did so. */
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
            /* XXX Clear stalls */
            ub_complete(&sc->work_done);
            return rc;
      }

      sc->work_timer.expires = jiffies + UB_URB_TIMEOUT;
      add_timer(&sc->work_timer);

      cmd->state = UB_CMDST_CMD;
      return 0;
}

/*
 * Timeout handler.
 */
static void ub_urb_timeout(unsigned long arg)
{
      struct ub_dev *sc = (struct ub_dev *) arg;
      unsigned long flags;

      spin_lock_irqsave(sc->lock, flags);
      if (!ub_is_completed(&sc->work_done))
            usb_unlink_urb(&sc->work_urb);
      spin_unlock_irqrestore(sc->lock, flags);
}

/*
 * Completion routine for the work URB.
 *
 * This can be called directly from usb_submit_urb (while we have
 * the sc->lock taken) and from an interrupt (while we do NOT have
 * the sc->lock taken). Therefore, bounce this off to a tasklet.
 */
static void ub_urb_complete(struct urb *urb, struct pt_regs *pt)
{
      struct ub_dev *sc = urb->context;

      ub_complete(&sc->work_done);
      tasklet_schedule(&sc->tasklet);
}

static void ub_scsi_action(unsigned long _dev)
{
      struct ub_dev *sc = (struct ub_dev *) _dev;
      unsigned long flags;

      spin_lock_irqsave(sc->lock, flags);
      ub_scsi_dispatch(sc);
      spin_unlock_irqrestore(sc->lock, flags);
}

static void ub_scsi_dispatch(struct ub_dev *sc)
{
      struct ub_scsi_cmd *cmd;
      int rc;

      while (!sc->reset && (cmd = ub_cmdq_peek(sc)) != NULL) {
            if (cmd->state == UB_CMDST_DONE) {
                  ub_cmdq_pop(sc);
                  (*cmd->done)(sc, cmd);
            } else if (cmd->state == UB_CMDST_INIT) {
                  if ((rc = ub_scsi_cmd_start(sc, cmd)) == 0)
                        break;
                  cmd->error = rc;
                  cmd->state = UB_CMDST_DONE;
            } else {
                  if (!ub_is_completed(&sc->work_done))
                        break;
                  del_timer(&sc->work_timer);
                  ub_scsi_urb_compl(sc, cmd);
            }
      }
}

static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct urb *urb = &sc->work_urb;
      struct bulk_cs_wrap *bcs;
      int len;
      int rc;

      if (atomic_read(&sc->poison)) {
            ub_state_done(sc, cmd, -ENODEV);
            return;
      }

      if (cmd->state == UB_CMDST_CLEAR) {
            if (urb->status == -EPIPE) {
                  /*
                   * STALL while clearning STALL.
                   * The control pipe clears itself - nothing to do.
                   */
                  printk(KERN_NOTICE "%s: stall on control pipe\n",
                      sc->name);
                  goto Bad_End;
            }

            /*
             * We ignore the result for the halt clear.
             */

            /* reset the endpoint toggle */
            usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
                  usb_pipeout(sc->last_pipe), 0);

            ub_state_sense(sc, cmd);

      } else if (cmd->state == UB_CMDST_CLR2STS) {
            if (urb->status == -EPIPE) {
                  printk(KERN_NOTICE "%s: stall on control pipe\n",
                      sc->name);
                  goto Bad_End;
            }

            /*
             * We ignore the result for the halt clear.
             */

            /* reset the endpoint toggle */
            usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
                  usb_pipeout(sc->last_pipe), 0);

            ub_state_stat(sc, cmd);

      } else if (cmd->state == UB_CMDST_CLRRS) {
            if (urb->status == -EPIPE) {
                  printk(KERN_NOTICE "%s: stall on control pipe\n",
                      sc->name);
                  goto Bad_End;
            }

            /*
             * We ignore the result for the halt clear.
             */

            /* reset the endpoint toggle */
            usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
                  usb_pipeout(sc->last_pipe), 0);

            ub_state_stat_counted(sc, cmd);

      } else if (cmd->state == UB_CMDST_CMD) {
            switch (urb->status) {
            case 0:
                  break;
            case -EOVERFLOW:
                  goto Bad_End;
            case -EPIPE:
                  rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
                  if (rc != 0) {
                        printk(KERN_NOTICE "%s: "
                            "unable to submit clear (%d)\n",
                            sc->name, rc);
                        /*
                         * This is typically ENOMEM or some other such shit.
                         * Retrying is pointless. Just do Bad End on it...
                         */
                        ub_state_done(sc, cmd, rc);
                        return;
                  }
                  cmd->state = UB_CMDST_CLEAR;
                  return;
            case -ESHUTDOWN:  /* unplug */
            case -EILSEQ:           /* unplug timeout on uhci */
                  ub_state_done(sc, cmd, -ENODEV);
                  return;
            default:
                  goto Bad_End;
            }
            if (urb->actual_length != US_BULK_CB_WRAP_LEN) {
                  goto Bad_End;
            }

            if (cmd->dir == UB_DIR_NONE || cmd->nsg < 1) {
                  ub_state_stat(sc, cmd);
                  return;
            }

            // udelay(125);         // usb-storage has this
            ub_data_start(sc, cmd);

      } else if (cmd->state == UB_CMDST_DATA) {
            if (urb->status == -EPIPE) {
                  rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
                  if (rc != 0) {
                        printk(KERN_NOTICE "%s: "
                            "unable to submit clear (%d)\n",
                            sc->name, rc);
                        ub_state_done(sc, cmd, rc);
                        return;
                  }
                  cmd->state = UB_CMDST_CLR2STS;
                  return;
            }
            if (urb->status == -EOVERFLOW) {
                  /*
                   * A babble? Failure, but we must transfer CSW now.
                   */
                  cmd->error = -EOVERFLOW;      /* A cheap trick... */
                  ub_state_stat(sc, cmd);
                  return;
            }

            if (cmd->dir == UB_DIR_WRITE) {
                  /*
                   * Do not continue writes in case of a failure.
                   * Doing so would cause sectors to be mixed up,
                   * which is worse than sectors lost.
                   *
                   * We must try to read the CSW, or many devices
                   * get confused.
                   */
                  len = urb->actual_length;
                  if (urb->status != 0 ||
                      len != cmd->sgv[cmd->current_sg].length) {
                        cmd->act_len += len;

                        cmd->error = -EIO;
                        ub_state_stat(sc, cmd);
                        return;
                  }

            } else {
                  /*
                   * If an error occurs on read, we record it, and
                   * continue to fetch data in order to avoid bubble.
                   *
                   * As a small shortcut, we stop if we detect that
                   * a CSW mixed into data.
                   */
                  if (urb->status != 0)
                        cmd->error = -EIO;

                  len = urb->actual_length;
                  if (urb->status != 0 ||
                      len != cmd->sgv[cmd->current_sg].length) {
                        if ((len & 0x1FF) == US_BULK_CS_WRAP_LEN)
                              goto Bad_End;
                  }
            }

            cmd->act_len += urb->actual_length;

            if (++cmd->current_sg < cmd->nsg) {
                  ub_data_start(sc, cmd);
                  return;
            }
            ub_state_stat(sc, cmd);

      } else if (cmd->state == UB_CMDST_STAT) {
            if (urb->status == -EPIPE) {
                  rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
                  if (rc != 0) {
                        printk(KERN_NOTICE "%s: "
                            "unable to submit clear (%d)\n",
                            sc->name, rc);
                        ub_state_done(sc, cmd, rc);
                        return;
                  }

                  /*
                   * Having a stall when getting CSW is an error, so
                   * make sure uppper levels are not oblivious to it.
                   */
                  cmd->error = -EIO;            /* A cheap trick... */

                  cmd->state = UB_CMDST_CLRRS;
                  return;
            }

            /* Catch everything, including -EOVERFLOW and other nasties. */
            if (urb->status != 0)
                  goto Bad_End;

            if (urb->actual_length == 0) {
                  ub_state_stat_counted(sc, cmd);
                  return;
            }

            /*
             * Check the returned Bulk protocol status.
             * The status block has to be validated first.
             */

            bcs = &sc->work_bcs;

            if (sc->signature == cpu_to_le32(0)) {
                  /*
                   * This is the first reply, so do not perform the check.
                   * Instead, remember the signature the device uses
                   * for future checks. But do not allow a nul.
                   */
                  sc->signature = bcs->Signature;
                  if (sc->signature == cpu_to_le32(0)) {
                        ub_state_stat_counted(sc, cmd);
                        return;
                  }
            } else {
                  if (bcs->Signature != sc->signature) {
                        ub_state_stat_counted(sc, cmd);
                        return;
                  }
            }

            if (bcs->Tag != cmd->tag) {
                  /*
                   * This usually happens when we disagree with the
                   * device's microcode about something. For instance,
                   * a few of them throw this after timeouts. They buffer
                   * commands and reply at commands we timed out before.
                   * Without flushing these replies we loop forever.
                   */
                  ub_state_stat_counted(sc, cmd);
                  return;
            }

            len = le32_to_cpu(bcs->Residue);
            if (len != cmd->len - cmd->act_len) {
                  /*
                   * It is all right to transfer less, the caller has
                   * to check. But it's not all right if the device
                   * counts disagree with our counts.
                   */
                  goto Bad_End;
            }

            switch (bcs->Status) {
            case US_BULK_STAT_OK:
                  break;
            case US_BULK_STAT_FAIL:
                  ub_state_sense(sc, cmd);
                  return;
            case US_BULK_STAT_PHASE:
                  goto Bad_End;
            default:
                  printk(KERN_INFO "%s: unknown CSW status 0x%x\n",
                      sc->name, bcs->Status);
                  ub_state_done(sc, cmd, -EINVAL);
                  return;
            }

            /* Not zeroing error to preserve a babble indicator */
            if (cmd->error != 0) {
                  ub_state_sense(sc, cmd);
                  return;
            }
            cmd->state = UB_CMDST_DONE;
            ub_cmdq_pop(sc);
            (*cmd->done)(sc, cmd);

      } else if (cmd->state == UB_CMDST_SENSE) {
            ub_state_done(sc, cmd, -EIO);

      } else {
            printk(KERN_WARNING "%s: "
                "wrong command state %d\n",
                sc->name, cmd->state);
            ub_state_done(sc, cmd, -EINVAL);
            return;
      }
      return;

Bad_End: /* Little Excel is dead */
      ub_state_done(sc, cmd, -EIO);
}

/*
 * Factorization helper for the command state machine:
 * Initiate a data segment transfer.
 */
static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct scatterlist *sg = &cmd->sgv[cmd->current_sg];
      int pipe;
      int rc;

      UB_INIT_COMPLETION(sc->work_done);

      if (cmd->dir == UB_DIR_READ)
            pipe = sc->recv_bulk_pipe;
      else
            pipe = sc->send_bulk_pipe;
      sc->last_pipe = pipe;
      usb_fill_bulk_urb(&sc->work_urb, sc->dev, pipe,
          page_address(sg->page) + sg->offset, sg->length,
          ub_urb_complete, sc);
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
            /* XXX Clear stalls */
            ub_complete(&sc->work_done);
            ub_state_done(sc, cmd, rc);
            return;
      }

      sc->work_timer.expires = jiffies + UB_DATA_TIMEOUT;
      add_timer(&sc->work_timer);

      cmd->state = UB_CMDST_DATA;
}

/*
 * Factorization helper for the command state machine:
 * Finish the command.
 */
static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc)
{

      cmd->error = rc;
      cmd->state = UB_CMDST_DONE;
      ub_cmdq_pop(sc);
      (*cmd->done)(sc, cmd);
}

/*
 * Factorization helper for the command state machine:
 * Submit a CSW read.
 */
static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      int rc;

      UB_INIT_COMPLETION(sc->work_done);

      sc->last_pipe = sc->recv_bulk_pipe;
      usb_fill_bulk_urb(&sc->work_urb, sc->dev, sc->recv_bulk_pipe,
          &sc->work_bcs, US_BULK_CS_WRAP_LEN, ub_urb_complete, sc);
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
            /* XXX Clear stalls */
            ub_complete(&sc->work_done);
            ub_state_done(sc, cmd, rc);
            return -1;
      }

      sc->work_timer.expires = jiffies + UB_STAT_TIMEOUT;
      add_timer(&sc->work_timer);
      return 0;
}

/*
 * Factorization helper for the command state machine:
 * Submit a CSW read and go to STAT state.
 */
static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{

      if (__ub_state_stat(sc, cmd) != 0)
            return;

      cmd->stat_count = 0;
      cmd->state = UB_CMDST_STAT;
}

/*
 * Factorization helper for the command state machine:
 * Submit a CSW read and go to STAT state with counter (along [C] path).
 */
static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{

      if (++cmd->stat_count >= 4) {
            ub_state_sense(sc, cmd);
            return;
      }

      if (__ub_state_stat(sc, cmd) != 0)
            return;

      cmd->state = UB_CMDST_STAT;
}

/*
 * Factorization helper for the command state machine:
 * Submit a REQUEST SENSE and go to SENSE state.
 */
static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct ub_scsi_cmd *scmd;
      struct scatterlist *sg;
      int rc;

      if (cmd->cdb[0] == REQUEST_SENSE) {
            rc = -EPIPE;
            goto error;
      }

      scmd = &sc->top_rqs_cmd;
      memset(scmd, 0, sizeof(struct ub_scsi_cmd));
      scmd->cdb[0] = REQUEST_SENSE;
      scmd->cdb[4] = UB_SENSE_SIZE;
      scmd->cdb_len = 6;
      scmd->dir = UB_DIR_READ;
      scmd->state = UB_CMDST_INIT;
      scmd->nsg = 1;
      sg = &scmd->sgv[0];
      sg->page = virt_to_page(sc->top_sense);
      sg->offset = (unsigned long)sc->top_sense & (PAGE_SIZE-1);
      sg->length = UB_SENSE_SIZE;
      scmd->len = UB_SENSE_SIZE;
      scmd->lun = cmd->lun;
      scmd->done = ub_top_sense_done;
      scmd->back = cmd;

      scmd->tag = sc->tagcnt++;

      cmd->state = UB_CMDST_SENSE;

      ub_cmdq_insert(sc, scmd);
      return;

error:
      ub_state_done(sc, cmd, rc);
}

/*
 * A helper for the command's state machine:
 * Submit a stall clear.
 */
static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
    int stalled_pipe)
{
      int endp;
      struct usb_ctrlrequest *cr;
      int rc;

      endp = usb_pipeendpoint(stalled_pipe);
      if (usb_pipein (stalled_pipe))
            endp |= USB_DIR_IN;

      cr = &sc->work_cr;
      cr->bRequestType = USB_RECIP_ENDPOINT;
      cr->bRequest = USB_REQ_CLEAR_FEATURE;
      cr->wValue = cpu_to_le16(USB_ENDPOINT_HALT);
      cr->wIndex = cpu_to_le16(endp);
      cr->wLength = cpu_to_le16(0);

      UB_INIT_COMPLETION(sc->work_done);

      usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
          (unsigned char*) cr, NULL, 0, ub_urb_complete, sc);
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
            ub_complete(&sc->work_done);
            return rc;
      }

      sc->work_timer.expires = jiffies + UB_CTRL_TIMEOUT;
      add_timer(&sc->work_timer);
      return 0;
}

/*
 */
static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd)
{
      unsigned char *sense = sc->top_sense;
      struct ub_scsi_cmd *cmd;

      /*
       * Find the command which triggered the unit attention or a check,
       * save the sense into it, and advance its state machine.
       */
      if ((cmd = ub_cmdq_peek(sc)) == NULL) {
            printk(KERN_WARNING "%s: sense done while idle\n", sc->name);
            return;
      }
      if (cmd != scmd->back) {
            printk(KERN_WARNING "%s: "
                "sense done for wrong command 0x%x\n",
                sc->name, cmd->tag);
            return;
      }
      if (cmd->state != UB_CMDST_SENSE) {
            printk(KERN_WARNING "%s: "
                "sense done with bad cmd state %d\n",
                sc->name, cmd->state);
            return;
      }

      /*
       * Ignoring scmd->act_len, because the buffer was pre-zeroed.
       */
      cmd->key = sense[2] & 0x0F;
      cmd->asc = sense[12];
      cmd->ascq = sense[13];

      ub_scsi_urb_compl(sc, cmd);
}

/*
 * Reset management
 * XXX Move usb_reset_device to khubd. Hogging kevent is not a good thing.
 * XXX Make usb_sync_reset asynchronous.
 */

static void ub_reset_enter(struct ub_dev *sc, int try)
{

      if (sc->reset) {
            /* This happens often on multi-LUN devices. */
            return;
      }
      sc->reset = try + 1;

#if 0 /* Not needed because the disconnect waits for us. */
      unsigned long flags;
      spin_lock_irqsave(&ub_lock, flags);
      sc->openc++;
      spin_unlock_irqrestore(&ub_lock, flags);
#endif

#if 0 /* We let them stop themselves. */
      struct list_head *p;
      struct ub_lun *lun;
      list_for_each(p, &sc->luns) {
            lun = list_entry(p, struct ub_lun, link);
            blk_stop_queue(lun->disk->queue);
      }
#endif

      schedule_work(&sc->reset_work);
}

static void ub_reset_task(void *arg)
{
      struct ub_dev *sc = arg;
      unsigned long flags;
      struct list_head *p;
      struct ub_lun *lun;
      int lkr, rc;

      if (!sc->reset) {
            printk(KERN_WARNING "%s: Running reset unrequested\n",
                sc->name);
            return;
      }

      if (atomic_read(&sc->poison)) {
            ;
      } else if ((sc->reset & 1) == 0) {
            ub_sync_reset(sc);
            msleep(700);      /* usb-storage sleeps 6s (!) */
            ub_probe_clear_stall(sc, sc->recv_bulk_pipe);
            ub_probe_clear_stall(sc, sc->send_bulk_pipe);
      } else if (sc->dev->actconfig->desc.bNumInterfaces != 1) {
            ;
      } else {
            if ((lkr = usb_lock_device_for_reset(sc->dev, sc->intf)) < 0) {
                  printk(KERN_NOTICE
                      "%s: usb_lock_device_for_reset failed (%d)\n",
                      sc->name, lkr);
            } else {
                  rc = usb_reset_device(sc->dev);
                  if (rc < 0) {
                        printk(KERN_NOTICE "%s: "
                            "usb_lock_device_for_reset failed (%d)\n",
                            sc->name, rc);
                  }

                  if (lkr)
                        usb_unlock_device(sc->dev);
            }
      }

      /*
       * In theory, no commands can be running while reset is active,
       * so nobody can ask for another reset, and so we do not need any
       * queues of resets or anything. We do need a spinlock though,
       * to interact with block layer.
       */
      spin_lock_irqsave(sc->lock, flags);
      sc->reset = 0;
      tasklet_schedule(&sc->tasklet);
      list_for_each(p, &sc->luns) {
            lun = list_entry(p, struct ub_lun, link);
            blk_start_queue(lun->disk->queue);
      }
      wake_up(&sc->reset_wait);
      spin_unlock_irqrestore(sc->lock, flags);
}

/*
 * This is called from a process context.
 */
static void ub_revalidate(struct ub_dev *sc, struct ub_lun *lun)
{

      lun->readonly = 0;      /* XXX Query this from the device */

      lun->capacity.nsec = 0;
      lun->capacity.bsize = 512;
      lun->capacity.bshift = 0;

      if (ub_sync_tur(sc, lun) != 0)
            return;                 /* Not ready */
      lun->changed = 0;

      if (ub_sync_read_cap(sc, lun, &lun->capacity) != 0) {
            /*
             * The retry here means something is wrong, either with the
             * device, with the transport, or with our code.
             * We keep this because sd.c has retries for capacity.
             */
            if (ub_sync_read_cap(sc, lun, &lun->capacity) != 0) {
                  lun->capacity.nsec = 0;
                  lun->capacity.bsize = 512;
                  lun->capacity.bshift = 0;
            }
      }
}

/*
 * The open funcion.
 * This is mostly needed to keep refcounting, but also to support
 * media checks on removable media drives.
 */
static int ub_bd_open(struct inode *inode, struct file *filp)
{
      struct gendisk *disk = inode->i_bdev->bd_disk;
      struct ub_lun *lun = disk->private_data;
      struct ub_dev *sc = lun->udev;
      unsigned long flags;
      int rc;

      spin_lock_irqsave(&ub_lock, flags);
      if (atomic_read(&sc->poison)) {
            spin_unlock_irqrestore(&ub_lock, flags);
            return -ENXIO;
      }
      sc->openc++;
      spin_unlock_irqrestore(&ub_lock, flags);

      if (lun->removable || lun->readonly)
            check_disk_change(inode->i_bdev);

      /*
       * The sd.c considers ->media_present and ->changed not equivalent,
       * under some pretty murky conditions (a failure of READ CAPACITY).
       * We may need it one day.
       */
      if (lun->removable && lun->changed && !(filp->f_flags & O_NDELAY)) {
            rc = -ENOMEDIUM;
            goto err_open;
      }

      if (lun->readonly && (filp->f_mode & FMODE_WRITE)) {
            rc = -EROFS;
            goto err_open;
      }

      return 0;

err_open:
      ub_put(sc);
      return rc;
}

/*
 */
static int ub_bd_release(struct inode *inode, struct file *filp)
{
      struct gendisk *disk = inode->i_bdev->bd_disk;
      struct ub_lun *lun = disk->private_data;
      struct ub_dev *sc = lun->udev;

      ub_put(sc);
      return 0;
}

/*
 * The ioctl interface.
 */
static int ub_bd_ioctl(struct inode *inode, struct file *filp,
    unsigned int cmd, unsigned long arg)
{
      struct gendisk *disk = inode->i_bdev->bd_disk;
      void __user *usermem = (void __user *) arg;

      return scsi_cmd_ioctl(filp, disk, cmd, usermem);
}

/*
 * This is called once a new disk was seen by the block layer or by ub_probe().
 * The main onjective here is to discover the features of the media such as
 * the capacity, read-only status, etc. USB storage generally does not
 * need to be spun up, but if we needed it, this would be the place.
 *
 * This call can sleep.
 *
 * The return code is not used.
 */
static int ub_bd_revalidate(struct gendisk *disk)
{
      struct ub_lun *lun = disk->private_data;

      ub_revalidate(lun->udev, lun);

      /* XXX Support sector size switching like in sr.c */
      blk_queue_hardsect_size(disk->queue, lun->capacity.bsize);
      set_capacity(disk, lun->capacity.nsec);
      // set_disk_ro(sdkp->disk, lun->readonly);

      return 0;
}

/*
 * The check is called by the block layer to verify if the media
 * is still available. It is supposed to be harmless, lightweight and
 * non-intrusive in case the media was not changed.
 *
 * This call can sleep.
 *
 * The return code is bool!
 */
static int ub_bd_media_changed(struct gendisk *disk)
{
      struct ub_lun *lun = disk->private_data;

      if (!lun->removable)
            return 0;

      /*
       * We clean checks always after every command, so this is not
       * as dangerous as it looks. If the TEST_UNIT_READY fails here,
       * the device is actually not ready with operator or software
       * intervention required. One dangerous item might be a drive which
       * spins itself down, and come the time to write dirty pages, this
       * will fail, then block layer discards the data. Since we never
       * spin drives up, such devices simply cannot be used with ub anyway.
       */
      if (ub_sync_tur(lun->udev, lun) != 0) {
            lun->changed = 1;
            return 1;
      }

      return lun->changed;
}

static struct block_device_operations ub_bd_fops = {
      .owner            = THIS_MODULE,
      .open       = ub_bd_open,
      .release    = ub_bd_release,
      .ioctl            = ub_bd_ioctl,
      .media_changed    = ub_bd_media_changed,
      .revalidate_disk = ub_bd_revalidate,
};

/*
 * Common ->done routine for commands executed synchronously.
 */
static void ub_probe_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
      struct completion *cop = cmd->back;
      complete(cop);
}

/*
 * Test if the device has a check condition on it, synchronously.
 */
static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun)
{
      struct ub_scsi_cmd *cmd;
      enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) };
      unsigned long flags;
      struct completion compl;
      int rc;

      init_completion(&compl);

      rc = -ENOMEM;
      if ((cmd = kzalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
            goto err_alloc;

      cmd->cdb[0] = TEST_UNIT_READY;
      cmd->cdb_len = 6;
      cmd->dir = UB_DIR_NONE;
      cmd->state = UB_CMDST_INIT;
      cmd->lun = lun;               /* This may be NULL, but that's ok */
      cmd->done = ub_probe_done;
      cmd->back = &compl;

      spin_lock_irqsave(sc->lock, flags);
      cmd->tag = sc->tagcnt++;

      rc = ub_submit_scsi(sc, cmd);
      spin_unlock_irqrestore(sc->lock, flags);

      if (rc != 0)
            goto err_submit;

      wait_for_completion(&compl);

      rc = cmd->error;

      if (rc == -EIO && cmd->key != 0)    /* Retries for benh's key */
            rc = cmd->key;

err_submit:
      kfree(cmd);
err_alloc:
      return rc;
}

/*
 * Read the SCSI capacity synchronously (for probing).
 */
static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_capacity *ret)
{
      struct ub_scsi_cmd *cmd;
      struct scatterlist *sg;
      char *p;
      enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) + 8 };
      unsigned long flags;
      unsigned int bsize, shift;
      unsigned long nsec;
      struct completion compl;
      int rc;

      init_completion(&compl);

      rc = -ENOMEM;
      if ((cmd = kzalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
            goto err_alloc;
      p = (char *)cmd + sizeof(struct ub_scsi_cmd);

      cmd->cdb[0] = 0x25;
      cmd->cdb_len = 10;
      cmd->dir = UB_DIR_READ;
      cmd->state = UB_CMDST_INIT;
      cmd->nsg = 1;
      sg = &cmd->sgv[0];
      sg->page = virt_to_page(p);
      sg->offset = (unsigned long)p & (PAGE_SIZE-1);
      sg->length = 8;
      cmd->len = 8;
      cmd->lun = lun;
      cmd->done = ub_probe_done;
      cmd->back = &compl;

      spin_lock_irqsave(sc->lock, flags);
      cmd->tag = sc->tagcnt++;

      rc = ub_submit_scsi(sc, cmd);
      spin_unlock_irqrestore(sc->lock, flags);

      if (rc != 0)
            goto err_submit;

      wait_for_completion(&compl);

      if (cmd->error != 0) {
            rc = -EIO;
            goto err_read;
      }
      if (cmd->act_len != 8) {
            rc = -EIO;
            goto err_read;
      }

      /* sd.c special-cases sector size of 0 to mean 512. Needed? Safe? */
      nsec = be32_to_cpu(*(__be32 *)p) + 1;
      bsize = be32_to_cpu(*(__be32 *)(p + 4));
      switch (bsize) {
      case 512:   shift = 0;  break;
      case 1024:  shift = 1;  break;
      case 2048:  shift = 2;  break;
      case 4096:  shift = 3;  break;
      default:
            rc = -EDOM;
            goto err_inv_bsize;
      }

      ret->bsize = bsize;
      ret->bshift = shift;
      ret->nsec = nsec << shift;
      rc = 0;

err_inv_bsize:
err_read:
err_submit:
      kfree(cmd);
err_alloc:
      return rc;
}

/*
 */
static void ub_probe_urb_complete(struct urb *urb, struct pt_regs *pt)
{
      struct completion *cop = urb->context;
      complete(cop);
}

static void ub_probe_timeout(unsigned long arg)
{
      struct completion *cop = (struct completion *) arg;
      complete(cop);
}

/*
 * Reset with a Bulk reset.
 */
static int ub_sync_reset(struct ub_dev *sc)
{
      int ifnum = sc->intf->cur_altsetting->desc.bInterfaceNumber;
      struct usb_ctrlrequest *cr;
      struct completion compl;
      struct timer_list timer;
      int rc;

      init_completion(&compl);

      cr = &sc->work_cr;
      cr->bRequestType = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
      cr->bRequest = US_BULK_RESET_REQUEST;
      cr->wValue = cpu_to_le16(0);
      cr->wIndex = cpu_to_le16(ifnum);
      cr->wLength = cpu_to_le16(0);

      usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
          (unsigned char*) cr, NULL, 0, ub_probe_urb_complete, &compl);
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0) {
            printk(KERN_WARNING
                 "%s: Unable to submit a bulk reset (%d)\n", sc->name, rc);
            return rc;
      }

      init_timer(&timer);
      timer.function = ub_probe_timeout;
      timer.data = (unsigned long) &compl;
      timer.expires = jiffies + UB_CTRL_TIMEOUT;
      add_timer(&timer);

      wait_for_completion(&compl);

      del_timer_sync(&timer);
      usb_kill_urb(&sc->work_urb);

      return sc->work_urb.status;
}

/*
 * Get number of LUNs by the way of Bulk GetMaxLUN command.
 */
static int ub_sync_getmaxlun(struct ub_dev *sc)
{
      int ifnum = sc->intf->cur_altsetting->desc.bInterfaceNumber;
      unsigned char *p;
      enum { ALLOC_SIZE = 1 };
      struct usb_ctrlrequest *cr;
      struct completion compl;
      struct timer_list timer;
      int nluns;
      int rc;

      init_completion(&compl);

      rc = -ENOMEM;
      if ((p = kmalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
            goto err_alloc;
      *p = 55;

      cr = &sc->work_cr;
      cr->bRequestType = USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE;
      cr->bRequest = US_BULK_GET_MAX_LUN;
      cr->wValue = cpu_to_le16(0);
      cr->wIndex = cpu_to_le16(ifnum);
      cr->wLength = cpu_to_le16(1);

      usb_fill_control_urb(&sc->work_urb, sc->dev, sc->recv_ctrl_pipe,
          (unsigned char*) cr, p, 1, ub_probe_urb_complete, &compl);
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0)
            goto err_submit;

      init_timer(&timer);
      timer.function = ub_probe_timeout;
      timer.data = (unsigned long) &compl;
      timer.expires = jiffies + UB_CTRL_TIMEOUT;
      add_timer(&timer);

      wait_for_completion(&compl);

      del_timer_sync(&timer);
      usb_kill_urb(&sc->work_urb);

      if ((rc = sc->work_urb.status) < 0)
            goto err_io;

      if (sc->work_urb.actual_length != 1) {
            nluns = 0;
      } else {
            if ((nluns = *p) == 55) {
                  nluns = 0;
            } else {
                  /* GetMaxLUN returns the maximum LUN number */
                  nluns += 1;
                  if (nluns > UB_MAX_LUNS)
                        nluns = UB_MAX_LUNS;
            }
      }

      kfree(p);
      return nluns;

err_io:
err_submit:
      kfree(p);
err_alloc:
      return rc;
}

/*
 * Clear initial stalls.
 */
static int ub_probe_clear_stall(struct ub_dev *sc, int stalled_pipe)
{
      int endp;
      struct usb_ctrlrequest *cr;
      struct completion compl;
      struct timer_list timer;
      int rc;

      init_completion(&compl);

      endp = usb_pipeendpoint(stalled_pipe);
      if (usb_pipein (stalled_pipe))
            endp |= USB_DIR_IN;

      cr = &sc->work_cr;
      cr->bRequestType = USB_RECIP_ENDPOINT;
      cr->bRequest = USB_REQ_CLEAR_FEATURE;
      cr->wValue = cpu_to_le16(USB_ENDPOINT_HALT);
      cr->wIndex = cpu_to_le16(endp);
      cr->wLength = cpu_to_le16(0);

      usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
          (unsigned char*) cr, NULL, 0, ub_probe_urb_complete, &compl);
      sc->work_urb.actual_length = 0;
      sc->work_urb.error_count = 0;
      sc->work_urb.status = 0;

      if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0) {
            printk(KERN_WARNING
                 "%s: Unable to submit a probe clear (%d)\n", sc->name, rc);
            return rc;
      }

      init_timer(&timer);
      timer.function = ub_probe_timeout;
      timer.data = (unsigned long) &compl;
      timer.expires = jiffies + UB_CTRL_TIMEOUT;
      add_timer(&timer);

      wait_for_completion(&compl);

      del_timer_sync(&timer);
      usb_kill_urb(&sc->work_urb);

      /* reset the endpoint toggle */
      usb_settoggle(sc->dev, endp, usb_pipeout(sc->last_pipe), 0);

      return 0;
}

/*
 * Get the pipe settings.
 */
static int ub_get_pipes(struct ub_dev *sc, struct usb_device *dev,
    struct usb_interface *intf)
{
      struct usb_host_interface *altsetting = intf->cur_altsetting;
      struct usb_endpoint_descriptor *ep_in = NULL;
      struct usb_endpoint_descriptor *ep_out = NULL;
      struct usb_endpoint_descriptor *ep;
      int i;

      /*
       * Find the endpoints we need.
       * We are expecting a minimum of 2 endpoints - in and out (bulk).
       * We will ignore any others.
       */
      for (i = 0; i < altsetting->desc.bNumEndpoints; i++) {
            ep = &altsetting->endpoint[i].desc;

            /* Is it a BULK endpoint? */
            if ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
                        == USB_ENDPOINT_XFER_BULK) {
                  /* BULK in or out? */
                  if (ep->bEndpointAddress & USB_DIR_IN)
                        ep_in = ep;
                  else
                        ep_out = ep;
            }
      }

      if (ep_in == NULL || ep_out == NULL) {
            printk(KERN_NOTICE "%s: failed endpoint check\n",
                sc->name);
            return -ENODEV;
      }

      /* Calculate and store the pipe values */
      sc->send_ctrl_pipe = usb_sndctrlpipe(dev, 0);
      sc->recv_ctrl_pipe = usb_rcvctrlpipe(dev, 0);
      sc->send_bulk_pipe = usb_sndbulkpipe(dev,
            ep_out->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
      sc->recv_bulk_pipe = usb_rcvbulkpipe(dev, 
            ep_in->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);

      return 0;
}

/*
 * Probing is done in the process context, which allows us to cheat
 * and not to build a state machine for the discovery.
 */
static int ub_probe(struct usb_interface *intf,
    const struct usb_device_id *dev_id)
{
      struct ub_dev *sc;
      int nluns;
      int rc;
      int i;

      if (usb_usual_check_type(dev_id, USB_US_TYPE_UB))
            return -ENXIO;

      rc = -ENOMEM;
      if ((sc = kzalloc(sizeof(struct ub_dev), GFP_KERNEL)) == NULL)
            goto err_core;
      sc->lock = ub_next_lock();
      INIT_LIST_HEAD(&sc->luns);
      usb_init_urb(&sc->work_urb);
      tasklet_init(&sc->tasklet, ub_scsi_action, (unsigned long)sc);
      atomic_set(&sc->poison, 0);
      INIT_WORK(&sc->reset_work, ub_reset_task, sc);
      init_waitqueue_head(&sc->reset_wait);

      init_timer(&sc->work_timer);
      sc->work_timer.data = (unsigned long) sc;
      sc->work_timer.function = ub_urb_timeout;

      ub_init_completion(&sc->work_done);
      sc->work_done.done = 1;       /* A little yuk, but oh well... */

      sc->dev = interface_to_usbdev(intf);
      sc->intf = intf;
      // sc->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
      usb_set_intfdata(intf, sc);
      usb_get_dev(sc->dev);
      /*
       * Since we give the interface struct to the block level through
       * disk->driverfs_dev, we have to pin it. Otherwise, block_uevent
       * oopses on close after a disconnect (kernels 2.6.16 and up).
       */
      usb_get_intf(sc->intf);

      snprintf(sc->name, 12, DRV_NAME "(%d.%d)",
          sc->dev->bus->busnum, sc->dev->devnum);

      /* XXX Verify that we can handle the device (from descriptors) */

      if (ub_get_pipes(sc, sc->dev, intf) != 0)
            goto err_dev_desc;

      /*
       * At this point, all USB initialization is done, do upper layer.
       * We really hate halfway initialized structures, so from the
       * invariants perspective, this ub_dev is fully constructed at
       * this point.
       */

      /*
       * This is needed to clear toggles. It is a problem only if we do
       * `rmmod ub && modprobe ub` without disconnects, but we like that.
       */
#if 0 /* iPod Mini fails if we do this (big white iPod works) */
      ub_probe_clear_stall(sc, sc->recv_bulk_pipe);
      ub_probe_clear_stall(sc, sc->send_bulk_pipe);
#endif

      /*
       * The way this is used by the startup code is a little specific.
       * A SCSI check causes a USB stall. Our common case code sees it
       * and clears the check, after which the device is ready for use.
       * But if a check was not present, any command other than
       * TEST_UNIT_READY ends with a lockup (including REQUEST_SENSE).
       *
       * If we neglect to clear the SCSI check, the first real command fails
       * (which is the capacity readout). We clear that and retry, but why
       * causing spurious retries for no reason.
       *
       * Revalidation may start with its own TEST_UNIT_READY, but that one
       * has to succeed, so we clear checks with an additional one here.
       * In any case it's not our business how revaliadation is implemented.
       */
      for (i = 0; i < 3; i++) {  /* Retries for the schwag key from KS'04 */
            if ((rc = ub_sync_tur(sc, NULL)) <= 0) break;
            if (rc != 0x6) break;
            msleep(10);
      }

      nluns = 1;
      for (i = 0; i < 3; i++) {
            if ((rc = ub_sync_getmaxlun(sc)) < 0)
                  break;
            if (rc != 0) {
                  nluns = rc;
                  break;
            }
            msleep(100);
      }

      for (i = 0; i < nluns; i++) {
            ub_probe_lun(sc, i);
      }
      return 0;

err_dev_desc:
      usb_set_intfdata(intf, NULL);
      usb_put_intf(sc->intf);
      usb_put_dev(sc->dev);
      kfree(sc);
err_core:
      return rc;
}

static int ub_probe_lun(struct ub_dev *sc, int lnum)
{
      struct ub_lun *lun;
      request_queue_t *q;
      struct gendisk *disk;
      int rc;

      rc = -ENOMEM;
      if ((lun = kzalloc(sizeof(struct ub_lun), GFP_KERNEL)) == NULL)
            goto err_alloc;
      lun->num = lnum;

      rc = -ENOSR;
      if ((lun->id = ub_id_get()) == -1)
            goto err_id;

      lun->udev = sc;

      snprintf(lun->name, 16, DRV_NAME "%c(%d.%d.%d)",
          lun->id + 'a', sc->dev->bus->busnum, sc->dev->devnum, lun->num);

      lun->removable = 1;           /* XXX Query this from the device */
      lun->changed = 1;       /* ub_revalidate clears only */
      ub_revalidate(sc, lun);

      rc = -ENOMEM;
      if ((disk = alloc_disk(UB_PARTS_PER_LUN)) == NULL)
            goto err_diskalloc;

      sprintf(disk->disk_name, DRV_NAME "%c", lun->id + 'a');
      disk->major = UB_MAJOR;
      disk->first_minor = lun->id * UB_PARTS_PER_LUN;
      disk->fops = &ub_bd_fops;
      disk->private_data = lun;
      disk->driverfs_dev = &sc->intf->dev;

      rc = -ENOMEM;
      if ((q = blk_init_queue(ub_request_fn, sc->lock)) == NULL)
            goto err_blkqinit;

      disk->queue = q;

      blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
      blk_queue_max_hw_segments(q, UB_MAX_REQ_SG);
      blk_queue_max_phys_segments(q, UB_MAX_REQ_SG);
      blk_queue_segment_boundary(q, 0xffffffff);      /* Dubious. */
      blk_queue_max_sectors(q, UB_MAX_SECTORS);
      blk_queue_hardsect_size(q, lun->capacity.bsize);

      lun->disk = disk;
      q->queuedata = lun;
      list_add(&lun->link, &sc->luns);

      set_capacity(disk, lun->capacity.nsec);
      if (lun->removable)
            disk->flags |= GENHD_FL_REMOVABLE;

      add_disk(disk);

      return 0;

err_blkqinit:
      put_disk(disk);
err_diskalloc:
      ub_id_put(lun->id);
err_id:
      kfree(lun);
err_alloc:
      return rc;
}

static void ub_disconnect(struct usb_interface *intf)
{
      struct ub_dev *sc = usb_get_intfdata(intf);
      struct list_head *p;
      struct ub_lun *lun;
      unsigned long flags;

      /*
       * Prevent ub_bd_release from pulling the rug from under us.
       * XXX This is starting to look like a kref.
       * XXX Why not to take this ref at probe time?
       */
      spin_lock_irqsave(&ub_lock, flags);
      sc->openc++;
      spin_unlock_irqrestore(&ub_lock, flags);

      /*
       * Fence stall clearnings, operations triggered by unlinkings and so on.
       * We do not attempt to unlink any URBs, because we do not trust the
       * unlink paths in HC drivers. Also, we get -84 upon disconnect anyway.
       */
      atomic_set(&sc->poison, 1);

      /*
       * Wait for reset to end, if any.
       */
      wait_event(sc->reset_wait, !sc->reset);

      /*
       * Blow away queued commands.
       *
       * Actually, this never works, because before we get here
       * the HCD terminates outstanding URB(s). It causes our
       * SCSI command queue to advance, commands fail to submit,
       * and the whole queue drains. So, we just use this code to
       * print warnings.
       */
      spin_lock_irqsave(sc->lock, flags);
      {
            struct ub_scsi_cmd *cmd;
            int cnt = 0;
            while ((cmd = ub_cmdq_peek(sc)) != NULL) {
                  cmd->error = -ENOTCONN;
                  cmd->state = UB_CMDST_DONE;
                  ub_cmdq_pop(sc);
                  (*cmd->done)(sc, cmd);
                  cnt++;
            }
            if (cnt != 0) {
                  printk(KERN_WARNING "%s: "
                      "%d was queued after shutdown\n", sc->name, cnt);
            }
      }
      spin_unlock_irqrestore(sc->lock, flags);

      /*
       * Unregister the upper layer.
       */
      list_for_each (p, &sc->luns) {
            lun = list_entry(p, struct ub_lun, link);
            del_gendisk(lun->disk);
            /*
             * I wish I could do:
             *    set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
             * As it is, we rely on our internal poisoning and let
             * the upper levels to spin furiously failing all the I/O.
             */
      }

      /*
       * Testing for -EINPROGRESS is always a bug, so we are bending
       * the rules a little.
       */
      spin_lock_irqsave(sc->lock, flags);
      if (sc->work_urb.status == -EINPROGRESS) {      /* janitors: ignore */
            printk(KERN_WARNING "%s: "
                "URB is active after disconnect\n", sc->name);
      }
      spin_unlock_irqrestore(sc->lock, flags);

      /*
       * There is virtually no chance that other CPU runs times so long
       * after ub_urb_complete should have called del_timer, but only if HCD
       * didn't forget to deliver a callback on unlink.
       */
      del_timer_sync(&sc->work_timer);

      /*
       * At this point there must be no commands coming from anyone
       * and no URBs left in transit.
       */

      ub_put(sc);
}

static struct usb_driver ub_driver = {
      .name =           "ub",
      .probe =    ub_probe,
      .disconnect =     ub_disconnect,
      .id_table = ub_usb_ids,
};

static int __init ub_init(void)
{
      int rc;
      int i;

      for (i = 0; i < UB_QLOCK_NUM; i++)
            spin_lock_init(&ub_qlockv[i]);

      if ((rc = register_blkdev(UB_MAJOR, DRV_NAME)) != 0)
            goto err_regblkdev;

      if ((rc = usb_register(&ub_driver)) != 0)
            goto err_register;

      usb_usual_set_present(USB_US_TYPE_UB);
      return 0;

err_register:
      unregister_blkdev(UB_MAJOR, DRV_NAME);
err_regblkdev:
      return rc;
}

static void __exit ub_exit(void)
{
      usb_deregister(&ub_driver);

      unregister_blkdev(UB_MAJOR, DRV_NAME);
      usb_usual_clear_present(USB_US_TYPE_UB);
}

module_init(ub_init);
module_exit(ub_exit);

MODULE_LICENSE("GPL");

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