Merge: [s390] s390/cio: Do not unregister the subchannel based on DNV

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/741

JIRA: https://issues.redhat.com/browse/RHEL-87158

commits;
```
8c58a22
```

Signed-off-by: Mete Durlu <mdurlu@redhat.com>

Approved-by: Steve Best <sbest@redhat.com>
Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Julio Faracco <jfaracco@redhat.com>

Author: jcfaracco

drivers/s390/cio/cio.c

@@ -459,10 +459,14 @@ int cio_update_schib(struct subchannel *sch)
 {
 	struct schib schib;
 
-	if (stsch(sch->schid, &schib) || !css_sch_is_valid(&schib))
+	if (stsch(sch->schid, &schib))
 		return -ENODEV;
 
 	memcpy(&sch->schib, &schib, sizeof(schib));
+
+	if (!css_sch_is_valid(&schib))
+		return -EACCES;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(cio_update_schib);

drivers/s390/cio/device.c

@@ -1387,21 +1387,35 @@ enum io_sch_action {
 	IO_SCH_VERIFY,
 	IO_SCH_DISC,
 	IO_SCH_NOP,
+	IO_SCH_ORPH_CDEV,
 };
 
 static enum io_sch_action sch_get_action(struct subchannel *sch)
 {
 	struct ccw_device *cdev;
+	int rc;
 
 	cdev = sch_get_cdev(sch);
-	if (cio_update_schib(sch)) {
+	rc = cio_update_schib(sch);
+
+	if (rc == -ENODEV) {
 		/* Not operational. */
 		if (!cdev)
 			return IO_SCH_UNREG;
 		if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
 			return IO_SCH_UNREG;
 		return IO_SCH_ORPH_UNREG;
 	}
+
+	/* Avoid unregistering subchannels without working device. */
+	if (rc == -EACCES) {
+		if (!cdev)
+			return IO_SCH_NOP;
+		if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
+			return IO_SCH_UNREG_CDEV;
+		return IO_SCH_ORPH_CDEV;
+	}
+
 	/* Operational. */
 	if (!cdev)
 		return IO_SCH_ATTACH;
@@ -1471,6 +1485,7 @@ static int io_subchannel_sch_event(struct subchannel *sch, int process)
 		rc = 0;
 		goto out_unlock;
 	case IO_SCH_ORPH_UNREG:
+	case IO_SCH_ORPH_CDEV:
 	case IO_SCH_ORPH_ATTACH:
 		ccw_device_set_disconnected(cdev);
 		break;
@@ -1502,6 +1517,7 @@ static int io_subchannel_sch_event(struct subchannel *sch, int process)
 	/* Handle attached ccw device. */
 	switch (action) {
 	case IO_SCH_ORPH_UNREG:
+	case IO_SCH_ORPH_CDEV:
 	case IO_SCH_ORPH_ATTACH:
 		/* Move ccw device to orphanage. */
 		rc = ccw_device_move_to_orph(cdev);