scsi.c

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

		cmd->result |= (DRIVER_SENSE << 24);

	SCSI_LOG_MLCOMPLETE(4, printk("Notifying upper driver of completion "
				"for device %d %x\n", sdev->id, cmd->result));

	cmd->owner = SCSI_OWNER_HIGHLEVEL;
	cmd->state = SCSI_STATE_FINISHED;

	/*
	 * We can get here with use_sg=0, causing a panic in the upper level
	 */
	cmd->use_sg = cmd->old_use_sg;

	/*
	 * If there is an associated request structure, copy the data over
	 * before we call the completion function.
	 */
	sreq = cmd->sc_request;
	if (sreq) {
	       sreq->sr_result = sreq->sr_command->result;
	       if (sreq->sr_result) {
		       memcpy(sreq->sr_sense_buffer,
			      sreq->sr_command->sense_buffer,
			      sizeof(sreq->sr_sense_buffer));
	       }
	}

	cmd->done(cmd);
}
EXPORT_SYMBOL(scsi_finish_command);

/*
 * Function:	scsi_adjust_queue_depth()
 *
 * Purpose:	Allow low level drivers to tell us to change the queue depth
 * 		on a specific SCSI device
 *
 * Arguments:	sdev	- SCSI Device in question
 * 		tagged	- Do we use tagged queueing (non-0) or do we treat
 * 			  this device as an untagged device (0)
 * 		tags	- Number of tags allowed if tagged queueing enabled,
 * 			  or number of commands the low level driver can
 * 			  queue up in non-tagged mode (as per cmd_per_lun).
 *
 * Returns:	Nothing
 *
 * Lock Status:	None held on entry
 *
 * Notes:	Low level drivers may call this at any time and we will do
 * 		the right thing depending on whether or not the device is
 * 		currently active and whether or not it even has the
 * 		command blocks built yet.
 *
 * XXX(hch):	What exactly is device_request_lock trying to protect?
 */
void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
{
	static spinlock_t device_request_lock = SPIN_LOCK_UNLOCKED;
	unsigned long flags;

	/*
	 * refuse to set tagged depth to an unworkable size
	 */
	if (tags <= 0)
		return;

	spin_lock_irqsave(&device_request_lock, flags);
	spin_lock(sdev->request_queue->queue_lock);

	/* Check to see if the queue is managed by the block layer
	 * if it is, and we fail to adjust the depth, exit */
	if (blk_queue_tagged(sdev->request_queue) &&
	    blk_queue_resize_tags(sdev->request_queue, tags) != 0)
		goto out;

	sdev->queue_depth = tags;
	switch (tagged) {
		case MSG_ORDERED_TAG:
			sdev->ordered_tags = 1;
			sdev->simple_tags = 1;
			break;
		case MSG_SIMPLE_TAG:
			sdev->ordered_tags = 0;
			sdev->simple_tags = 1;
			break;
		default:
			printk(KERN_WARNING "(scsi%d:%d:%d:%d) "
				"scsi_adjust_queue_depth, bad queue type, "
				"disabled\n", sdev->host->host_no,
				sdev->channel, sdev->id, sdev->lun); 
		case 0:
			sdev->ordered_tags = sdev->simple_tags = 0;
			sdev->queue_depth = tags;
			break;
	}
 out:
	spin_unlock(sdev->request_queue->queue_lock);
	spin_unlock_irqrestore(&device_request_lock, flags);
}

/*
 * Function:	scsi_track_queue_full()
 *
 * Purpose:	This function will track successive QUEUE_FULL events on a
 * 		specific SCSI device to determine if and when there is a
 * 		need to adjust the queue depth on the device.
 *
 * Arguments:	sdev	- SCSI Device in question
 * 		depth	- Current number of outstanding SCSI commands on
 * 			  this device, not counting the one returned as
 * 			  QUEUE_FULL.
 *
 * Returns:	0 - No change needed
 * 		>0 - Adjust queue depth to this new depth
 * 		-1 - Drop back to untagged operation using host->cmd_per_lun
 * 			as the untagged command depth
 *
 * Lock Status:	None held on entry
 *
 * Notes:	Low level drivers may call this at any time and we will do
 * 		"The Right Thing."  We are interrupt context safe.
 */
int scsi_track_queue_full(struct scsi_device *sdev, int depth)
{
	if ((jiffies >> 4) == sdev->last_queue_full_time)
		return 0;

	sdev->last_queue_full_time = (jiffies >> 4);
	if (sdev->last_queue_full_depth != depth) {
		sdev->last_queue_full_count = 1;
		sdev->last_queue_full_depth = depth;
	} else {
		sdev->last_queue_full_count++;
	}

	if (sdev->last_queue_full_count <= 10)
		return 0;
	if (sdev->last_queue_full_depth < 8) {
		/* Drop back to untagged */
		scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
		return -1;
	}
	
	if (sdev->ordered_tags)
		scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
	else
		scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
	return depth;
}

/**
 * scsi_device_get  -  get an addition reference to a scsi_device
 * @sdev:	device to get a reference to
 *
 * Gets a reference to the scsi_device and increments the use count
 * of the underlying LLDD module.  You must hold host_lock of the
 * parent Scsi_Host or already have a reference when calling this.
 */
int scsi_device_get(struct scsi_device *sdev)
{
	if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
		return -ENXIO;
	if (!get_device(&sdev->sdev_gendev))
		return -ENXIO;
	if (!try_module_get(sdev->host->hostt->module)) {
		put_device(&sdev->sdev_gendev);
		return -ENXIO;
	}
	return 0;
}
EXPORT_SYMBOL(scsi_device_get);

/**
 * scsi_device_put  -  release a reference to a scsi_device
 * @sdev:	device to release a reference on.
 *
 * Release a reference to the scsi_device and decrements the use count
 * of the underlying LLDD module.  The device is freed once the last
 * user vanishes.
 */
void scsi_device_put(struct scsi_device *sdev)
{
	module_put(sdev->host->hostt->module);
	put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_device_put);

/* helper for shost_for_each_device, thus not documented */
struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
					   struct scsi_device *prev)
{
	struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
	struct scsi_device *next = NULL;
	unsigned long flags;

	spin_lock_irqsave(shost->host_lock, flags);
	while (list->next != &shost->__devices) {
		next = list_entry(list->next, struct scsi_device, siblings);
		/* skip devices that we can't get a reference to */
		if (!scsi_device_get(next))
			break;
		list = list->next;
	}
	spin_unlock_irqrestore(shost->host_lock, flags);

	if (prev)
		scsi_device_put(prev);
	return next;
}
EXPORT_SYMBOL(__scsi_iterate_devices);

/**
 * scsi_device_lookup - find a device given the host (UNLOCKED)
 * @shost:	SCSI host pointer
 * @channel:	SCSI channel (zero if only one channel)
 * @pun:	SCSI target number (physical unit number)
 * @lun:	SCSI Logical Unit Number
 *
 * Looks up the scsi_device with the specified @channel, @id, @lun for a
 * give host. The returned scsi_device does not have an additional reference.
 * You must hold the host's host_lock over this call and any access to the
 * returned scsi_device.
 *
 * Note:  The only reason why drivers would want to use this is because
 * they're need to access the device list in irq context.  Otherwise you
 * really want to use scsi_device_lookup instead.
 **/
struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
		uint channel, uint id, uint lun)
{
	struct scsi_device *sdev;

	list_for_each_entry(sdev, &shost->__devices, siblings) {
		if (sdev->channel == channel && sdev->id == id &&
				sdev->lun ==lun)
			return sdev;
	}

	return NULL;
}
EXPORT_SYMBOL(__scsi_device_lookup);

/**
 * scsi_device_lookup - find a device given the host
 * @shost:	SCSI host pointer
 * @channel:	SCSI channel (zero if only one channel)
 * @id:		SCSI target number (physical unit number)
 * @lun:	SCSI Logical Unit Number
 *
 * Looks up the scsi_device with the specified @channel, @id, @lun for a
 * give host.  The returned scsi_device has an additional reference that
 * needs to be release with scsi_host_put once you're done with it.
 **/
struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
		uint channel, uint id, uint lun)
{
	struct scsi_device *sdev;
	unsigned long flags;

	spin_lock_irqsave(shost->host_lock, flags);
	sdev = __scsi_device_lookup(shost, channel, id, lun);
	if (sdev && scsi_device_get(sdev))
		sdev = NULL;
	spin_unlock_irqrestore(shost->host_lock, flags);

	return sdev;
}
EXPORT_SYMBOL(scsi_device_lookup);

/**
 * scsi_device_cancel - cancel outstanding IO to this device
 * @sdev:	pointer to struct scsi_device
 * @data:	pointer to cancel value.
 *
 **/
int scsi_device_cancel(struct scsi_device *sdev, int recovery)
{
	struct scsi_cmnd *scmd;
	LIST_HEAD(active_list);
	struct list_head *lh, *lh_sf;
	unsigned long flags;

	scsi_device_set_state(sdev, SDEV_CANCEL);

	spin_lock_irqsave(&sdev->list_lock, flags);
	list_for_each_entry(scmd, &sdev->cmd_list, list) {
		if (scmd->request && scmd->request->rq_status != RQ_INACTIVE) {
			/*
			 * If we are unable to remove the timer, it means
			 * that the command has already timed out or
			 * finished.
			 */
			if (!scsi_delete_timer(scmd))
				continue;
			list_add_tail(&scmd->eh_entry, &active_list);
		}
	}
	spin_unlock_irqrestore(&sdev->list_lock, flags);

	if (!list_empty(&active_list)) {
		list_for_each_safe(lh, lh_sf, &active_list) {
			scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
			list_del_init(lh);
			if (recovery) {
				scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
			} else {
				scmd->result = (DID_ABORT << 16);
				scsi_finish_command(scmd);
			}
		}
	}

	return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static int scsi_cpu_notify(struct notifier_block *self,
			   unsigned long action, void *hcpu)
{
	int cpu = (unsigned long)hcpu;

	switch(action) {
	case CPU_DEAD:
		/* Drain scsi_done_q. */
		local_irq_disable();
		list_splice_init(&per_cpu(scsi_done_q, cpu),
				 &__get_cpu_var(scsi_done_q));
		raise_softirq_irqoff(SCSI_SOFTIRQ);
		local_irq_enable();
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block __devinitdata scsi_cpu_nb = {
	.notifier_call	= scsi_cpu_notify,
};

#define register_scsi_cpu() register_cpu_notifier(&scsi_cpu_nb)
#define unregister_scsi_cpu() unregister_cpu_notifier(&scsi_cpu_nb)
#else
#define register_scsi_cpu()
#define unregister_scsi_cpu()
#endif /* CONFIG_HOTPLUG_CPU */

MODULE_DESCRIPTION("SCSI core");
MODULE_LICENSE("GPL");

module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");

static int __init init_scsi(void)
{
	int error, i;

	error = scsi_init_queue();
	if (error)
		return error;
	error = scsi_init_procfs();
	if (error)
		goto cleanup_queue;
	error = scsi_init_devinfo();
	if (error)
		goto cleanup_procfs;
	error = scsi_init_hosts();
	if (error)
		goto cleanup_devlist;
	error = scsi_init_sysctl();
	if (error)
		goto cleanup_hosts;
	error = scsi_sysfs_register();
	if (error)
		goto cleanup_sysctl;

	for (i = 0; i < NR_CPUS; i++)
		INIT_LIST_HEAD(&per_cpu(scsi_done_q, i));

	devfs_mk_dir("scsi");
	open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);
	register_scsi_cpu();
	printk(KERN_NOTICE "SCSI subsystem initialized\n");
	return 0;

cleanup_sysctl:
	scsi_exit_sysctl();
cleanup_hosts:
	scsi_exit_hosts();
cleanup_devlist:
	scsi_exit_devinfo();
cleanup_procfs:
	scsi_exit_procfs();
cleanup_queue:
	scsi_exit_queue();
	printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
	       -error);
	return error;
}

static void __exit exit_scsi(void)
{
	scsi_sysfs_unregister();
	scsi_exit_sysctl();
	scsi_exit_hosts();
	scsi_exit_devinfo();
	devfs_remove("scsi");
	scsi_exit_procfs();
	scsi_exit_queue();
	unregister_scsi_cpu();
}

subsys_initcall(init_scsi);
module_exit(exit_scsi);