static unsigned int sd_check_events(struct gendisk *disk, unsigned int clearing)
{
	struct scsi_disk *sdkp = scsi_disk(disk);
	struct scsi_device *sdp = sdkp->device;
	struct scsi_sense_hdr *sshdr = NULL;
	int retval;

	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_check_events\n"));

	/*
	 * If the device is offline, don't send any commands - just pretend as
	 * if the command failed.  If the device ever comes back online, we
	 * can deal with it then.  It is only because of unrecoverable errors
	 * that we would ever take a device offline in the first place.
	 */
	if (!scsi_device_online(sdp)) {
		set_media_not_present(sdkp);
		goto out;
	}

	/*
	 * Using TEST_UNIT_READY enables differentiation between drive with
	 * no cartridge loaded - NOT READY, drive with changed cartridge -
	 * UNIT ATTENTION, or with same cartridge - GOOD STATUS.
	 *
	 * Drives that auto spin down. eg iomega jaz 1G, will be started
	 * by sd_spinup_disk() from sd_revalidate_disk(), which happens whenever
	 * sd_revalidate() is called.
	 */
	retval = -ENODEV;

	if (scsi_block_when_processing_errors(sdp)) {
		sshdr  = kzalloc(sizeof(*sshdr), GFP_KERNEL);
		retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, SD_MAX_RETRIES,
					      sshdr);
	}

	/* failed to execute TUR, assume media not present */
	if (host_byte(retval)) {
		set_media_not_present(sdkp);
		goto out;
	}

	if (media_not_present(sdkp, sshdr))
		goto out;

	/*
	 * For removable scsi disk we have to recognise the presence
	 * of a disk in the drive.
	 */
	if (!sdkp->media_present)
		sdp->changed = 1;
	sdkp->media_present = 1;
out:
	/*
	 * sdp->changed is set under the following conditions:
	 *
	 *	Medium present state has changed in either direction.
	 *	Device has indicated UNIT_ATTENTION.
	 */
	kfree(sshdr);
	retval = sdp->changed ? DISK_EVENT_MEDIA_CHANGE : 0;
	sdp->changed = 0;
	return retval;
}
static unsigned int sd_check_events(struct gendisk *disk, unsigned int clearing)
{
	struct scsi_disk *sdkp = scsi_disk(disk);
	struct scsi_device *sdp = sdkp->device;
	struct scsi_sense_hdr *sshdr = NULL;
	int retval;

	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_check_events\n"));

	 
	if (!scsi_device_online(sdp)) {
		set_media_not_present(sdkp);
		goto out;
	}

	 
	retval = -ENODEV;

	if (scsi_block_when_processing_errors(sdp)) {
		sshdr  = kzalloc(sizeof(*sshdr), GFP_KERNEL);
		retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, SD_MAX_RETRIES,
					      sshdr);
	}

	 
	if (host_byte(retval)) {
		set_media_not_present(sdkp);
		goto out;
	}

	if (media_not_present(sdkp, sshdr))
		goto out;

	 
	if (!sdkp->media_present)
		sdp->changed = 1;
	sdkp->media_present = 1;
out:
	 
	kfree(sshdr);
	retval = sdp->changed ? DISK_EVENT_MEDIA_CHANGE : 0;
	sdp->changed = 0;
	return retval;
}