ub.c

linux 内核源代码

	}
}

/*
 * Final cleanup and deallocation.
 */
static void ub_cleanup(struct ub_dev *sc)
{
	struct list_head *p;
	struct ub_lun *lun;
	struct request_queue *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(struct request_queue *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)) {
		blkdev_dequeue_request(rq);
		ub_end_rq(rq, DID_NO_CONNECT << 16);
		return 0;
	}

	if (lun->changed && !blk_pc_request(rq)) {
		blkdev_dequeue_request(rq);
		ub_end_rq(rq, SAM_STAT_CHECK_CONDITION);
		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));
	sg_init_table(cmd->sgv, UB_MAX_REQ_SG);

	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, DID_ERROR << 16);
	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;
	unsigned int scsi_status;

	rq = urq->rq;

	if (cmd->error == 0) {
		if (blk_pc_request(rq)) {
			if (cmd->act_len >= rq->data_len)
				rq->data_len = 0;
			else
				rq->data_len -= cmd->act_len;
		}
		scsi_status = 0;
	} else {
		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)
				scsi_status = SAM_STAT_CHECK_CONDITION;
			else
				scsi_status = DID_ERROR << 16;
		} else {
			if (cmd->error == -EIO) {
				if (ub_rw_cmd_retry(sc, lun, urq, cmd) == 0)
					return;
			}
			scsi_status = SAM_STAT_CHECK_CONDITION;
		}
	}

	urq->rq = NULL;

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

static void ub_end_rq(struct request *rq, unsigned int scsi_status)
{
	int uptodate;

	if (scsi_status == 0) {
		uptodate = 1;
	} else {
		uptodate = 0;
		rq->errors = scsi_status;
	}
	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 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)