[S390] dasd: let device initialization wait for LCU setup

The first DASD that is set online for a specific logical control unit
has to do certain setup steps on the storage server to make full use
of it, for example it will enable PAV.
The features and characteristics reported by the storage server will
depend on this setup, so all other devices on the same LCU will need
to wait for the setup to be finished.
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/block/dasd_alias.c

@@ -152,6 +152,7 @@ static struct alias_lcu *_allocate_lcu(struct dasd_uid *uid)
 	INIT_WORK(&lcu->suc_data.worker, summary_unit_check_handling_work);
 	INIT_DELAYED_WORK(&lcu->ruac_data.dwork, lcu_update_work);
 	spin_lock_init(&lcu->lock);
+	init_completion(&lcu->lcu_setup);
 	return lcu;
 
 out_err4:
@@ -239,6 +240,67 @@ int dasd_alias_make_device_known_to_lcu(struct dasd_device *device)
 	return is_lcu_known;
 }
 
+/*
+ * The first device to be registered on an LCU will have to do
+ * some additional setup steps to configure that LCU on the
+ * storage server. All further devices should wait with their
+ * initialization until the first device is done.
+ * To synchronize this work, the first device will call
+ * dasd_alias_lcu_setup_complete when it is done, and all
+ * other devices will wait for it with dasd_alias_wait_for_lcu_setup.
+ */
+void dasd_alias_lcu_setup_complete(struct dasd_device *device)
+{
+	struct dasd_eckd_private *private;
+	unsigned long flags;
+	struct alias_server *server;
+	struct alias_lcu *lcu;
+	struct dasd_uid *uid;
+
+	private = (struct dasd_eckd_private *) device->private;
+	uid = &private->uid;
+	lcu = NULL;
+	spin_lock_irqsave(&aliastree.lock, flags);
+	server = _find_server(uid);
+	if (server)
+		lcu = _find_lcu(server, uid);
+	spin_unlock_irqrestore(&aliastree.lock, flags);
+	if (!lcu) {
+		DBF_EVENT_DEVID(DBF_ERR, device->cdev,
+				"could not find lcu for %04x %02x",
+				uid->ssid, uid->real_unit_addr);
+		WARN_ON(1);
+		return;
+	}
+	complete_all(&lcu->lcu_setup);
+}
+
+void dasd_alias_wait_for_lcu_setup(struct dasd_device *device)
+{
+	struct dasd_eckd_private *private;
+	unsigned long flags;
+	struct alias_server *server;
+	struct alias_lcu *lcu;
+	struct dasd_uid *uid;
+
+	private = (struct dasd_eckd_private *) device->private;
+	uid = &private->uid;
+	lcu = NULL;
+	spin_lock_irqsave(&aliastree.lock, flags);
+	server = _find_server(uid);
+	if (server)
+		lcu = _find_lcu(server, uid);
+	spin_unlock_irqrestore(&aliastree.lock, flags);
+	if (!lcu) {
+		DBF_EVENT_DEVID(DBF_ERR, device->cdev,
+				"could not find lcu for %04x %02x",
+				uid->ssid, uid->real_unit_addr);
+		WARN_ON(1);
+		return;
+	}
+	wait_for_completion(&lcu->lcu_setup);
+}
+
 /*
  * This function removes a device from the scope of alias management.
  * The complicated part is to make sure that it is not in use by

drivers/s390/block/dasd_eckd.c

@@ -1059,7 +1059,7 @@ dasd_eckd_psf_ssc(struct dasd_device *device, int enable_pav)
 /*
  * Valide storage server of current device.
  */
-static int dasd_eckd_validate_server(struct dasd_device *device)
+static void dasd_eckd_validate_server(struct dasd_device *device)
 {
 	int rc;
 	struct dasd_eckd_private *private;
@@ -1076,8 +1076,6 @@ static int dasd_eckd_validate_server(struct dasd_device *device)
 	private = (struct dasd_eckd_private *) device->private;
 	DBF_EVENT_DEVID(DBF_WARNING, device->cdev, "PSF-SSC for SSID %04x "
 			"returned rc=%d", private->uid.ssid, rc);
-	/* RE-Read Configuration Data */
-	return dasd_eckd_read_conf(device);
 }
 
 /*
@@ -1149,12 +1147,21 @@ dasd_eckd_check_characteristics(struct dasd_device *device)
 		rc = is_known;
 		goto out_err2;
 	}
+	/*
+	 * dasd_eckd_vaildate_server is done on the first device that
+	 * is found for an LCU. All later other devices have to wait
+	 * for it, so they will read the correct feature codes.
+	 */
 	if (!is_known) {
-		/* new lcu found */
-		rc = dasd_eckd_validate_server(device); /* will switch pav on */
-		if (rc)
-			goto out_err3;
-	}
+		dasd_eckd_validate_server(device);
+		dasd_alias_lcu_setup_complete(device);
+	} else
+		dasd_alias_wait_for_lcu_setup(device);
+
+	/* device may report different configuration data after LCU setup */
+	rc = dasd_eckd_read_conf(device);
+	if (rc)
+		goto out_err3;
 
 	/* Read Feature Codes */
 	dasd_eckd_read_features(device);
@@ -3282,11 +3289,15 @@ int dasd_eckd_restore_device(struct dasd_device *device)
 	if (is_known < 0)
 		return is_known;
 	if (!is_known) {
-		/* new lcu found */
-		rc = dasd_eckd_validate_server(device); /* will switch pav on */
-		if (rc)
-			goto out_err;
-	}
+		dasd_eckd_validate_server(device);
+		dasd_alias_lcu_setup_complete(device);
+	} else
+		dasd_alias_wait_for_lcu_setup(device);
+
+	/* RE-Read Configuration Data */
+	rc = dasd_eckd_read_conf(device);
+	if (rc)
+		goto out_err;
 
 	/* Read Feature Codes */
 	dasd_eckd_read_features(device);

drivers/s390/block/dasd_eckd.h

@@ -414,6 +414,7 @@ struct alias_lcu {
 	struct summary_unit_check_work_data suc_data;
 	struct read_uac_work_data ruac_data;
 	struct dasd_ccw_req *rsu_cqr;
+	struct completion lcu_setup;
 };
 
 struct alias_pav_group {
@@ -460,5 +461,6 @@ int dasd_alias_remove_device(struct dasd_device *);
 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *);
 void dasd_alias_handle_summary_unit_check(struct dasd_device *, struct irb *);
 void dasd_eckd_reset_ccw_to_base_io(struct dasd_ccw_req *);
-
+void dasd_alias_lcu_setup_complete(struct dasd_device *);
+void dasd_alias_wait_for_lcu_setup(struct dasd_device *);
 #endif				/* DASD_ECKD_H */