scsi.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,249 行 · 第 1/3 页

		}
	}
}

void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
{
	unsigned int level;
	struct scsi_device *sdev;

	/*
	 * If ML COMPLETE log level is greater than or equal to:
	 *
	 * 1: log disposition, result, opcode + command, and conditionally
	 * sense data for failures or non SUCCESS dispositions.
	 *
	 * 2: same as 1 but for all command completions.
	 *
	 * 3: same as 2 plus dump cmd address
	 *
	 * 4: same as 3 plus dump extra junk
	 */
	if (unlikely(scsi_logging_level)) {
		level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
				       SCSI_LOG_MLCOMPLETE_BITS);
		if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
		    (level > 1)) {
			sdev = cmd->device;
			printk(KERN_INFO "scsi <%d:%d:%d:%d> done ",
			       sdev->host->host_no, sdev->channel, sdev->id,
			       sdev->lun);
			if (level > 2)
				printk("0x%p ", cmd);
			/*
			 * Dump truncated values, so we usually fit within
			 * 80 chars.
			 */
			switch (disposition) {
			case SUCCESS:
				printk("SUCCESS");
				break;
			case NEEDS_RETRY:
				printk("RETRY  ");
				break;
			case ADD_TO_MLQUEUE:
				printk("MLQUEUE");
				break;
			case FAILED:
				printk("FAILED ");
				break;
			case TIMEOUT_ERROR:
				/* 
				 * If called via scsi_times_out.
				 */
				printk("TIMEOUT");
				break;
			default:
				printk("UNKNOWN");
			}
			printk(" %8x ", cmd->result);
			scsi_print_command(cmd);
			if (status_byte(cmd->result) & CHECK_CONDITION) {
				/*
				 * XXX The print_sense formatting/prefix
				 * doesn't match this function.
				 */
				scsi_print_sense("", cmd);
			}
			if (level > 3) {
				printk(KERN_INFO "scsi host busy %d failed %d\n",
				       sdev->host->host_busy,
				       sdev->host->host_failed);
			}
		}
	}
}
#endif

/*
 * Function:    scsi_dispatch_command
 *
 * Purpose:     Dispatch a command to the low-level driver.
 *
 * Arguments:   cmd - command block we are dispatching.
 *
 * Notes:
 */
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
	struct Scsi_Host *host = cmd->device->host;
	unsigned long flags = 0;
	unsigned long timeout;
	int rtn = 0;

	/* check if the device is still usable */
	if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
		/* in SDEV_DEL we error all commands. DID_NO_CONNECT
		 * returns an immediate error upwards, and signals
		 * that the device is no longer present */
		cmd->result = DID_NO_CONNECT << 16;
		scsi_done(cmd);
		/* return 0 (because the command has been processed) */
		goto out;
	}
	/* Assign a unique nonzero serial_number. */
	/* XXX(hch): this is racy */
	if (++serial_number == 0)
		serial_number = 1;
	cmd->serial_number = serial_number;
	cmd->pid = scsi_pid++;

	/* 
	 * If SCSI-2 or lower, store the LUN value in cmnd.
	 */
	if (cmd->device->scsi_level <= SCSI_2) {
		cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
			       (cmd->device->lun << 5 & 0xe0);
	}

	/*
	 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
	 * we can avoid the drive not being ready.
	 */
	timeout = host->last_reset + MIN_RESET_DELAY;

	if (host->resetting && time_before(jiffies, timeout)) {
		int ticks_remaining = timeout - jiffies;
		/*
		 * NOTE: This may be executed from within an interrupt
		 * handler!  This is bad, but for now, it'll do.  The irq
		 * level of the interrupt handler has been masked out by the
		 * platform dependent interrupt handling code already, so the
		 * sti() here will not cause another call to the SCSI host's
		 * interrupt handler (assuming there is one irq-level per
		 * host).
		 */
		while (--ticks_remaining >= 0)
			mdelay(1 + 999 / HZ);
		host->resetting = 0;
	}

	scsi_add_timer(cmd, cmd->timeout_per_command, scsi_times_out);

	scsi_log_send(cmd);

	/*
	 * We will use a queued command if possible, otherwise we will
	 * emulate the queuing and calling of completion function ourselves.
	 */

	cmd->state = SCSI_STATE_QUEUED;
	cmd->owner = SCSI_OWNER_LOWLEVEL;

	/*
	 * Before we queue this command, check if the command
	 * length exceeds what the host adapter can handle.
	 */
	if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
		SCSI_LOG_MLQUEUE(3,
				printk("queuecommand : command too long.\n"));
		cmd->result = (DID_ABORT << 16);

		spin_lock_irqsave(host->host_lock, flags);
		scsi_done(cmd);
		spin_unlock_irqrestore(host->host_lock, flags);
		goto out;
	}

	spin_lock_irqsave(host->host_lock, flags);
	if (unlikely(test_bit(SHOST_CANCEL, &host->shost_state))) {
		cmd->result = (DID_NO_CONNECT << 16);
		scsi_done(cmd);
	} else {
		rtn = host->hostt->queuecommand(cmd, scsi_done);
	}
	spin_unlock_irqrestore(host->host_lock, flags);
	if (rtn) {
		scsi_queue_insert(cmd,
				(rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
				 rtn : SCSI_MLQUEUE_HOST_BUSY);
		SCSI_LOG_MLQUEUE(3,
		    printk("queuecommand : request rejected\n"));
	}

 out:
	SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
	return rtn;
}

/*
 * Function:    scsi_init_cmd_from_req
 *
 * Purpose:     Queue a SCSI command
 * Purpose:     Initialize a struct scsi_cmnd from a struct scsi_request
 *
 * Arguments:   cmd       - command descriptor.
 *              sreq      - Request from the queue.
 *
 * Lock status: None needed.
 *
 * Returns:     Nothing.
 *
 * Notes:       Mainly transfer data from the request structure to the
 *              command structure.  The request structure is allocated
 *              using the normal memory allocator, and requests can pile
 *              up to more or less any depth.  The command structure represents
 *              a consumable resource, as these are allocated into a pool
 *              when the SCSI subsystem initializes.  The preallocation is
 *              required so that in low-memory situations a disk I/O request
 *              won't cause the memory manager to try and write out a page.
 *              The request structure is generally used by ioctls and character
 *              devices.
 */
void scsi_init_cmd_from_req(struct scsi_cmnd *cmd, struct scsi_request *sreq)
{
	sreq->sr_command = cmd;

	cmd->owner = SCSI_OWNER_MIDLEVEL;
	cmd->cmd_len = sreq->sr_cmd_len;
	cmd->use_sg = sreq->sr_use_sg;

	cmd->request = sreq->sr_request;
	memcpy(cmd->data_cmnd, sreq->sr_cmnd, sizeof(cmd->data_cmnd));
	cmd->serial_number = 0;
	cmd->serial_number_at_timeout = 0;
	cmd->bufflen = sreq->sr_bufflen;
	cmd->buffer = sreq->sr_buffer;
	cmd->retries = 0;
	cmd->allowed = sreq->sr_allowed;
	cmd->done = sreq->sr_done;
	cmd->timeout_per_command = sreq->sr_timeout_per_command;
	cmd->sc_data_direction = sreq->sr_data_direction;
	cmd->sglist_len = sreq->sr_sglist_len;
	cmd->underflow = sreq->sr_underflow;
	cmd->sc_request = sreq;
	memcpy(cmd->cmnd, sreq->sr_cmnd, sizeof(sreq->sr_cmnd));

	/*
	 * Zero the sense buffer.  Some host adapters automatically request
	 * sense on error.  0 is not a valid sense code.
	 */
	memset(cmd->sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
	cmd->request_buffer = sreq->sr_buffer;
	cmd->request_bufflen = sreq->sr_bufflen;
	cmd->old_use_sg = cmd->use_sg;
	if (cmd->cmd_len == 0)
		cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
	cmd->old_cmd_len = cmd->cmd_len;
	cmd->sc_old_data_direction = cmd->sc_data_direction;
	cmd->old_underflow = cmd->underflow;

	/*
	 * Start the timer ticking.
	 */
	cmd->internal_timeout = NORMAL_TIMEOUT;
	cmd->abort_reason = 0;
	cmd->result = 0;

	SCSI_LOG_MLQUEUE(3, printk("Leaving scsi_init_cmd_from_req()\n"));
}

/*
 * Per-CPU I/O completion queue.
 */
static DEFINE_PER_CPU(struct list_head, scsi_done_q);

/**
 * scsi_done - Enqueue the finished SCSI command into the done queue.
 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
 *
 * This function is the mid-level's (SCSI Core) interrupt routine, which
 * regains ownership of the SCSI command (de facto) from a LLDD, and enqueues
 * the command to the done queue for further processing.
 *
 * This is the producer of the done queue who enqueues at the tail.
 *
 * This function is interrupt context safe.
 */
void scsi_done(struct scsi_cmnd *cmd)
{
	/*
	 * We don't have to worry about this one timing out any more.
	 * If we are unable to remove the timer, then the command
	 * has already timed out.  In which case, we have no choice but to
	 * let the timeout function run, as we have no idea where in fact
	 * that function could really be.  It might be on another processor,
	 * etc, etc.
	 */
	if (!scsi_delete_timer(cmd))
		return;
	__scsi_done(cmd);
}

/* Private entry to scsi_done() to complete a command when the timer
 * isn't running --- used by scsi_times_out */
void __scsi_done(struct scsi_cmnd *cmd)
{
	unsigned long flags;

	/*
	 * Set the serial numbers back to zero
	 */
	cmd->serial_number = 0;
	cmd->serial_number_at_timeout = 0;
	cmd->state = SCSI_STATE_BHQUEUE;
	cmd->owner = SCSI_OWNER_BH_HANDLER;

	/*
	 * Next, enqueue the command into the done queue.
	 * It is a per-CPU queue, so we just disable local interrupts
	 * and need no spinlock.
	 */
	local_irq_save(flags);
	list_add_tail(&cmd->eh_entry, &__get_cpu_var(scsi_done_q));
	raise_softirq_irqoff(SCSI_SOFTIRQ);
	local_irq_restore(flags);
}

/**
 * scsi_softirq - Perform post-interrupt processing of finished SCSI commands.
 *
 * This is the consumer of the done queue.
 *
 * This is called with all interrupts enabled.  This should reduce
 * interrupt latency, stack depth, and reentrancy of the low-level
 * drivers.
 */
static void scsi_softirq(struct softirq_action *h)
{
	int disposition;
	LIST_HEAD(local_q);

	local_irq_disable();
	list_splice_init(&__get_cpu_var(scsi_done_q), &local_q);
	local_irq_enable();

	while (!list_empty(&local_q)) {
		struct scsi_cmnd *cmd = list_entry(local_q.next,
						   struct scsi_cmnd, eh_entry);
		list_del_init(&cmd->eh_entry);

		disposition = scsi_decide_disposition(cmd);
		scsi_log_completion(cmd, disposition);
		switch (disposition) {
		case SUCCESS:
			scsi_finish_command(cmd);
			break;
		case NEEDS_RETRY:
			scsi_retry_command(cmd);
			break;
		case ADD_TO_MLQUEUE:
			scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
			break;
		default:
			if (!scsi_eh_scmd_add(cmd, 0))
				scsi_finish_command(cmd);
		}
	}
}

/*
 * Function:    scsi_retry_command
 *
 * Purpose:     Send a command back to the low level to be retried.
 *
 * Notes:       This command is always executed in the context of the
 *              bottom half handler, or the error handler thread. Low
 *              level drivers should not become re-entrant as a result of
 *              this.
 */
int scsi_retry_command(struct scsi_cmnd *cmd)
{
	/*
	 * Restore the SCSI command state.
	 */
	scsi_setup_cmd_retry(cmd);

        /*
         * Zero the sense information from the last time we tried
         * this command.
         */
	memset(cmd->sense_buffer, 0, sizeof(cmd->sense_buffer));

	return scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
}

/*
 * Function:    scsi_finish_command
 *
 * Purpose:     Pass command off to upper layer for finishing of I/O
 *              request, waking processes that are waiting on results,
 *              etc.
 */
void scsi_finish_command(struct scsi_cmnd *cmd)
{
	struct scsi_device *sdev = cmd->device;
	struct Scsi_Host *shost = sdev->host;
	struct scsi_request *sreq;

	scsi_device_unbusy(sdev);

        /*
         * Clear the flags which say that the device/host is no longer
         * capable of accepting new commands.  These are set in scsi_queue.c
         * for both the queue full condition on a device, and for a
         * host full condition on the host.
	 *
	 * XXX(hch): What about locking?
         */
        shost->host_blocked = 0;
        sdev->device_blocked = 0;

	/*
	 * If we have valid sense information, then some kind of recovery
	 * must have taken place.  Make a note of this.
	 */
	if (SCSI_SENSE_VALID(cmd))