scsi_debug 1.64 , remove detect(), "hotplug" hosts

This patch is against lk 2.5.46-bk3 which includes
Christoph's work removing the requirement for
detect() functions in LLDDs. He sent me an example
for scsi_debug which I have built on with this patch.

As threatened, this version includes a "scsi_debug_add_host"
parameter. At kernel or module load time this is an absolute
number (0..127 are allowable and 1 is the default). So:
     modprobe scsi_debug scsi_debug_num_devs=20 scsi_debug_add_host=0
will result in no scsi_debug hosts (thus no devices) but
the driver has 20 slots available for devices.

Then a host can be introduced (simulated hotplug) by
     echo 1 > /sysfs/bus/scsi/drivers/scsi_debug/add_host
This causes a scsi_debug host to appear and devices get
found on it [14 in my system: 7 targets (0..6) each with
2 luns (0..1)]. Another host hotplug can be simulated by
     echo 1 > /sysfs/bus/scsi/drivers/scsi_debug/add_host
which results in another 6 devices being attached (for a
total of 20 scsi_debug devices as dictated by the original
scsi_debug_num_devs).

That last (second) scsi_debug host can be removed by
     echo -1 > /sysfs/bus/scsi/drivers/scsi_debug/add_host
and its 6 devices go. Another application of this "echo"
removes the first host and all remaining devices.

Seems to work fine.

drivers/scsi/scsi_debug.h

 #ifndef _SCSI_DEBUG_H
 
 #include <linux/types.h>
-#include <linux/kdev_t.h>
 
-static int scsi_debug_detect(struct SHT *);
 static int scsi_debug_slave_attach(struct scsi_device *);
 static void scsi_debug_slave_detach(struct scsi_device *);
-static int scsi_debug_release(struct Scsi_Host *);
-/* static int scsi_debug_command(struct scsi_cmnd *); */
 static int scsi_debug_queuecommand(struct scsi_cmnd *, 
 				   void (*done) (struct scsi_cmnd *));
 static int scsi_debug_ioctl(struct scsi_device *, int, void *);
@@ -20,10 +16,6 @@ static int scsi_debug_host_reset(struct scsi_cmnd *);
 static int scsi_debug_proc_info(char *, char **, off_t, int, int, int);
 static const char * scsi_debug_info(struct Scsi_Host *);
 
-#ifndef NULL
-#define NULL 0
-#endif
-
 /*
  * This driver is written for the lk 2.5 series
  */
@@ -31,14 +23,12 @@ static const char * scsi_debug_info(struct Scsi_Host *);
 
 #define SCSI_DEBUG_MAX_CMD_LEN 16
 
-static Scsi_Host_Template driver_template = {
+static Scsi_Host_Template sdebug_driver_template = {
 	.proc_info =		scsi_debug_proc_info,
 	.name =			"SCSI DEBUG",
 	.info =			scsi_debug_info,
-	.detect =		scsi_debug_detect,
 	.slave_attach =		scsi_debug_slave_attach,
 	.slave_detach =		scsi_debug_slave_detach,
-	.release =		scsi_debug_release,
 	.ioctl =		scsi_debug_ioctl,
 	.queuecommand =		scsi_debug_queuecommand,
 	.eh_abort_handler =	scsi_debug_abort,
@@ -50,8 +40,9 @@ static Scsi_Host_Template driver_template = {
 	.this_id =		7,
 	.sg_tablesize =		64,
 	.cmd_per_lun =		3,
+	.max_sectors =		4096,
 	.unchecked_isa_dma = 	0,
 	.use_clustering = 	ENABLE_CLUSTERING,
-};	/* the name 'driver_template' is used by scsi_module.c */
+};
 
 #endif