scsi_debug: add cdb_len parameter

index 09ba494f8896..a573012524b3 100644
@@ -6,7 +6,7 @@
  *  anything out of the ordinary is seen.
  * ^^^^^^^^^^^^^^^^^^^^^^^ Original ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  *
- * Copyright (C) 2001 - 2016 Douglas Gilbert
+ * Copyright (C) 2001 - 2017 Douglas Gilbert
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

@@ -61,8 +61,8 @@
 #include "scsi_logging.h"
 
 /* make sure inq_product_rev string corresponds to this version */
-#define SDEBUG_VERSION "1.86"
-static const char *sdebug_version_date = "20160430";
+#define SDEBUG_VERSION "1.87"
+static const char *sdebug_version_date = "20171105";
 
 #define MY_NAME "scsi_debug"
 

@@ -105,6 +105,7 @@ static const char *sdebug_version_date = "20160430";
  * (id 0) containing 1 logical unit (lun 0). That is 1 device.
  */
 #define DEF_ATO 1
+#define DEF_CDB_LEN 10
 #define DEF_JDELAY   1		/* if > 0 unit is a jiffy */
 #define DEF_DEV_SIZE_MB   8
 #define DEF_DIF 0

@@ -571,6 +572,7 @@ static const struct opcode_info_t opcode_info_arr[SDEB_I_LAST_ELEMENT + 1] = {
 
 static int sdebug_add_host = DEF_NUM_HOST;
 static int sdebug_ato = DEF_ATO;
+static int sdebug_cdb_len = DEF_CDB_LEN;
 static int sdebug_jdelay = DEF_JDELAY;	/* if > 0 then unit is jiffies */
 static int sdebug_dev_size_mb = DEF_DEV_SIZE_MB;
 static int sdebug_dif = DEF_DIF;

@@ -797,6 +799,62 @@ static int scsi_debug_ioctl(struct scsi_device *dev, int cmd, void __user *arg)
 	/* return -ENOTTY; // correct return but upsets fdisk */
 }
 
+static void config_cdb_len(struct scsi_device * sdev)
+{
+	switch (sdebug_cdb_len) {
+	case 6:	/* suggest 6 byte READ, WRITE and MODE SENSE/SELECT */
+		sdev->use_10_for_rw = false;
+		sdev->use_16_for_rw = false;
+		sdev->use_10_for_ms = false;
+		break;
+	case 10: /* suggest 10 byte RWs and 6 byte MODE SENSE/SELECT */
+		sdev->use_10_for_rw = true;
+		sdev->use_16_for_rw = false;
+		sdev->use_10_for_ms = false;
+		break;
+	case 12: /* suggest 10 byte RWs and 10 byte MODE SENSE/SELECT */
+		sdev->use_10_for_rw = true;
+		sdev->use_16_for_rw = false;
+		sdev->use_10_for_ms = true;
+		break;
+	case 16:
+		sdev->use_10_for_rw = false;
+		sdev->use_16_for_rw = true;
+		sdev->use_10_for_ms = true;
+		break;
+	case 32: /* No knobs to suggest this so same as 16 for now */
+		sdev->use_10_for_rw = false;
+		sdev->use_16_for_rw = true;
+		sdev->use_10_for_ms = true;
+		break;
+	default:
+		pr_warn("unexpected cdb_len=%d, force to 10\n",
+			sdebug_cdb_len);
+		sdev->use_10_for_rw = true;
+		sdev->use_16_for_rw = false;
+		sdev->use_10_for_ms = false;
+		sdebug_cdb_len = 10;
+		break;
+	}
+}
+
+static void all_config_cdb_len(void)
+{
+	struct sdebug_host_info *sdbg_host;
+	struct Scsi_Host *shost;
+	struct scsi_device *sdev;
+
+
+	spin_lock(&sdebug_host_list_lock);
+	list_for_each_entry(sdbg_host, &sdebug_host_list, host_list) {
+		shost = sdbg_host->shost;
+		shost_for_each_device(sdev, shost) {
+			config_cdb_len(sdev);
+		}
+	}
+	spin_unlock(&sdebug_host_list_lock);
+}
+
 static void clear_luns_changed_on_target(struct sdebug_dev_info *devip)
 {
 	struct sdebug_host_info *sdhp;

@@ -3660,6 +3718,7 @@ static int scsi_debug_slave_configure(struct scsi_device *sdp)
 	blk_queue_max_segment_size(sdp->request_queue, -1U);
 	if (sdebug_no_uld)
 		sdp->no_uld_attach = 1;
+	config_cdb_len(sdp);
 	return 0;
 }
 

@@ -4141,6 +4200,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
  */
 module_param_named(add_host, sdebug_add_host, int, S_IRUGO | S_IWUSR);
 module_param_named(ato, sdebug_ato, int, S_IRUGO);
+module_param_named(cdb_len, sdebug_cdb_len, int, S_IRUGO | S_IWUSR);
 module_param_named(clustering, sdebug_clustering, bool, S_IRUGO | S_IWUSR);
 module_param_named(delay, sdebug_jdelay, int, S_IRUGO | S_IWUSR);
 module_param_named(dev_size_mb, sdebug_dev_size_mb, int, S_IRUGO);

@@ -4192,6 +4252,7 @@ MODULE_VERSION(SDEBUG_VERSION);
 
 MODULE_PARM_DESC(add_host, "0..127 hosts allowed(def=1)");
 MODULE_PARM_DESC(ato, "application tag ownership: 0=disk 1=host (def=1)");
+MODULE_PARM_DESC(cdb_len, "suggest CDB lengths to drivers (def=10)");
 MODULE_PARM_DESC(clustering, "when set enables larger transfers (def=0)");
 MODULE_PARM_DESC(delay, "response delay (def=1 jiffy); 0:imm, -1,-2:tiny");
 MODULE_PARM_DESC(dev_size_mb, "size in MiB of ram shared by devs(def=8)");

@@ -4875,6 +4936,24 @@ static ssize_t uuid_ctl_show(struct device_driver *ddp, char *buf)
 }
 static DRIVER_ATTR_RO(uuid_ctl);
 
+static ssize_t cdb_len_show(struct device_driver *ddp, char *buf)
+{
+	return scnprintf(buf, PAGE_SIZE, "%d\n", sdebug_cdb_len);
+}
+static ssize_t cdb_len_store(struct device_driver *ddp, const char *buf,
+			     size_t count)
+{
+	int n;
+
+	if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n >= 0)) {
+		sdebug_cdb_len = n;
+		all_config_cdb_len();
+		return count;
+	}
+	return -EINVAL;
+}
+static DRIVER_ATTR_RW(cdb_len);
+
 
 /* Note: The following array creates attribute files in the
    /sys/bus/pseudo/drivers/scsi_debug directory. The advantage of these

@@ -4914,6 +4993,7 @@ static struct attribute *sdebug_drv_attrs[] = {
 	&driver_attr_ndelay.attr,
 	&driver_attr_strict.attr,
 	&driver_attr_uuid_ctl.attr,
+	&driver_attr_cdb_len.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(sdebug_drv);