scsi: scsi_debug: Don't hold driver host struct pointer in host->hostdata[]

This driver stores just a pointer to the driver host structure in
host->hostdata[]. Most other drivers actually have the driver host
structure allocated in host->hostdata[], but this driver is different as we
allocate that memory separately before allocating the shost memory.

However there is no need to allocate this memory only in host->hostdata[]
when we can already look up the driver host structure from shost->dma_dev,
so add a macro for this - shost_to_sdebug_host(). Rename to_sdebug_host()
-> dev_to_sdebug_host() to avoid ambiguity.

Also remove a check for !sdbg_host in find_build_dev_info(), as this cannot
be true. Other similar checks will be later removed.
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20230313093114.1498305-2-john.g.garry@oracle.comAcked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_debug.c

@@ -324,9 +324,12 @@ struct sdeb_store_info {
 	void *map_storep;	/* provisioning map */
 };
 
-#define to_sdebug_host(d)	\
+#define dev_to_sdebug_host(d)	\
 	container_of(d, struct sdebug_host_info, dev)
 
+#define shost_to_sdebug_host(shost)	\
+	dev_to_sdebug_host(shost->dma_dev)
+
 enum sdeb_defer_type {SDEB_DEFER_NONE = 0, SDEB_DEFER_HRT = 1,
 		      SDEB_DEFER_WQ = 2, SDEB_DEFER_POLL = 3};
 
@@ -5166,11 +5169,7 @@ static struct sdebug_dev_info *find_build_dev_info(struct scsi_device *sdev)
 	struct sdebug_dev_info *open_devip = NULL;
 	struct sdebug_dev_info *devip;
 
-	sdbg_host = *(struct sdebug_host_info **)shost_priv(sdev->host);
-	if (!sdbg_host) {
-		pr_err("Host info NULL\n");
-		return NULL;
-	}
+	sdbg_host = shost_to_sdebug_host(sdev->host);
 
 	list_for_each_entry(devip, &sdbg_host->dev_info_list, dev_list) {
 		if ((devip->used) && (devip->channel == sdev->channel) &&
@@ -5407,7 +5406,7 @@ static int scsi_debug_target_reset(struct scsi_cmnd *SCpnt)
 	hp = sdp->host;
 	if (!hp)
 		goto lie;
-	sdbg_host = *(struct sdebug_host_info **)shost_priv(hp);
+	sdbg_host = shost_to_sdebug_host(hp);
 	if (sdbg_host) {
 		list_for_each_entry(devip,
 				    &sdbg_host->dev_info_list,
@@ -5440,7 +5439,7 @@ static int scsi_debug_bus_reset(struct scsi_cmnd *SCpnt)
 		sdev_printk(KERN_INFO, sdp, "%s\n", __func__);
 	hp = sdp->host;
 	if (hp) {
-		sdbg_host = *(struct sdebug_host_info **)shost_priv(hp);
+		sdbg_host = shost_to_sdebug_host(hp);
 		if (sdbg_host) {
 			list_for_each_entry(devip,
 					    &sdbg_host->dev_info_list,
@@ -7165,7 +7164,7 @@ static void sdebug_release_adapter(struct device *dev)
 {
 	struct sdebug_host_info *sdbg_host;
 
-	sdbg_host = to_sdebug_host(dev);
+	sdbg_host = dev_to_sdebug_host(dev);
 	kfree(sdbg_host);
 }
 
@@ -7812,14 +7811,14 @@ static int sdebug_driver_probe(struct device *dev)
 	struct Scsi_Host *hpnt;
 	int hprot;
 
-	sdbg_host = to_sdebug_host(dev);
+	sdbg_host = dev_to_sdebug_host(dev);
 
 	sdebug_driver_template.can_queue = sdebug_max_queue;
 	sdebug_driver_template.cmd_per_lun = sdebug_max_queue;
 	if (!sdebug_clustering)
 		sdebug_driver_template.dma_boundary = PAGE_SIZE - 1;
 
-	hpnt = scsi_host_alloc(&sdebug_driver_template, sizeof(sdbg_host));
+	hpnt = scsi_host_alloc(&sdebug_driver_template, 0);
 	if (NULL == hpnt) {
 		pr_err("scsi_host_alloc failed\n");
 		error = -ENODEV;
@@ -7862,7 +7861,6 @@ static int sdebug_driver_probe(struct device *dev)
 		hpnt->nr_maps = 3;
 
 	sdbg_host->shost = hpnt;
-	*((struct sdebug_host_info **)hpnt->hostdata) = sdbg_host;
 	if ((hpnt->this_id >= 0) && (sdebug_num_tgts > hpnt->this_id))
 		hpnt->max_id = sdebug_num_tgts + 1;
 	else
@@ -7936,7 +7934,7 @@ static void sdebug_driver_remove(struct device *dev)
 	struct sdebug_host_info *sdbg_host;
 	struct sdebug_dev_info *sdbg_devinfo, *tmp;
 
-	sdbg_host = to_sdebug_host(dev);
+	sdbg_host = dev_to_sdebug_host(dev);
 
 	scsi_remove_host(sdbg_host->shost);