scsi: core: Remove Scsi_Host.shost_dev_attr_groups

Simplify the scsi_host_alloc() implementation by setting the shost_class
.dev_groups member instead of copying all host attribute group pointers
into the shost_dev_attr_groups[] array.

Link: https://lore.kernel.org/r/20211116223115.2103031-1-bvanassche@acm.org
Cc: Steffen Maier <maier@linux.ibm.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Suggested-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hosts.c

@@ -61,6 +61,7 @@ static void scsi_host_cls_release(struct device *dev)
 static struct class shost_class = {
 	.name		= "scsi_host",
 	.dev_release	= scsi_host_cls_release,
+	.dev_groups	= scsi_shost_groups,
 };
 
 /**
@@ -377,7 +378,7 @@ static struct device_type scsi_host_type = {
 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 {
 	struct Scsi_Host *shost;
-	int index, i, j = 0;
+	int index;
 
 	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
 	if (!shost)
@@ -483,17 +484,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 	shost->shost_dev.parent = &shost->shost_gendev;
 	shost->shost_dev.class = &shost_class;
 	dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
-	shost->shost_dev.groups = shost->shost_dev_attr_groups;
-	shost->shost_dev_attr_groups[j++] = &scsi_shost_attr_group;
-	if (sht->shost_groups) {
-		for (i = 0; sht->shost_groups[i] &&
-			     j < ARRAY_SIZE(shost->shost_dev_attr_groups);
-		     i++, j++) {
-			shost->shost_dev_attr_groups[j] =
-				sht->shost_groups[i];
-		}
-	}
-	WARN_ON_ONCE(j >= ARRAY_SIZE(shost->shost_dev_attr_groups));
+	shost->shost_dev.groups = sht->shost_groups;
 
 	shost->ehandler = kthread_run(scsi_error_handler, shost,
 			"scsi_eh_%d", shost->host_no);

drivers/scsi/scsi_priv.h

@@ -144,7 +144,7 @@ extern struct scsi_transport_template blank_transport_template;
 extern void __scsi_remove_device(struct scsi_device *);
 
 extern struct bus_type scsi_bus_type;
-extern const struct attribute_group scsi_shost_attr_group;
+extern const struct attribute_group *scsi_shost_groups[];
 
 /* scsi_netlink.c */
 #ifdef CONFIG_SCSI_NETLINK

drivers/scsi/scsi_sysfs.c

@@ -424,10 +424,15 @@ static struct attribute *scsi_sysfs_shost_attrs[] = {
 	NULL
 };
 
-const struct attribute_group scsi_shost_attr_group = {
+static const struct attribute_group scsi_shost_attr_group = {
 	.attrs =	scsi_sysfs_shost_attrs,
 };
 
+const struct attribute_group *scsi_shost_groups[] = {
+	&scsi_shost_attr_group,
+	NULL
+};
+
 static void scsi_device_cls_release(struct device *class_dev)
 {
 	struct scsi_device *sdev;

include/scsi/scsi_host.h

@@ -691,12 +691,6 @@ struct Scsi_Host {
 
 	/* ldm bits */
 	struct device		shost_gendev, shost_dev;
-	/*
-	 * The array size 3 provides space for one attribute group defined by
-	 * the SCSI core, one attribute group defined by the SCSI LLD and one
-	 * terminating NULL pointer.
-	 */
-	const struct attribute_group *shost_dev_attr_groups[3];
 
 	/*
 	 * Points to the transport data (if any) which is allocated