[SCSI] Recognize missing LUNs for non-standard devices

Some non-standard SCSI targets or protocols, such as USB UFI, report "no
LUN present" by setting the Peripheral Device Type to 0x1f and the
Peripheral Qualifier to 0 (not 3 as the standard requires) in the INQUIRY
response.  This patch (as650b) adds a new target flag and code to
accomodate such targets.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_scan.c

@@ -853,6 +853,19 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
 		goto out_free_result;
 	}
 
+	/*
+	 * Non-standard SCSI targets may set the PDT to 0x1f (unknown or
+	 * no device type) instead of using the Peripheral Qualifier to
+	 * indicate that no LUN is present.  For example, USB UFI does this.
+	 */
+	if (starget->pdt_1f_for_no_lun && (result[0] & 0x1f) == 0x1f) {
+		SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
+					"scsi scan: peripheral device type"
+					" of 31, no device added\n"));
+		res = SCSI_SCAN_TARGET_PRESENT;
+		goto out_free_result;
+	}
+
 	res = scsi_add_lun(sdev, result, &bflags);
 	if (res == SCSI_SCAN_LUN_PRESENT) {
 		if (bflags & BLIST_KEY) {

include/scsi/scsi_device.h

@@ -167,7 +167,10 @@ struct scsi_target {
 	unsigned int		channel;
 	unsigned int		id; /* target id ... replace
 				     * scsi_device.id eventually */
-	unsigned long		create:1; /* signal that it needs to be added */
+	unsigned int		create:1; /* signal that it needs to be added */
+	unsigned int		pdt_1f_for_no_lun;	/* PDT = 0x1f */
+						/* means no lun present */
+
 	char			scsi_level;
 	void 			*hostdata; /* available to low-level driver */
 	unsigned long		starget_data[0]; /* for the transport */