[S390] dasd: add sanity check to detect path connection error

Prevents possible data corruption by detecting cabling error.
Therefor read and compare the UID for all available channel paths.
Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/block/dasd_eckd.c

@@ -752,24 +752,13 @@ dasd_eckd_cdl_reclen(int recid)
 		return sizes_trk0[recid];
 	return LABEL_SIZE;
 }
-
-/*
- * Generate device unique id that specifies the physical device.
- */
-static int dasd_eckd_generate_uid(struct dasd_device *device)
+/* create unique id from private structure. */
+static void create_uid(struct dasd_eckd_private *private)
 {
-	struct dasd_eckd_private *private;
-	struct dasd_uid *uid;
 	int count;
-	unsigned long flags;
+	struct dasd_uid *uid;
 
-	private = (struct dasd_eckd_private *) device->private;
-	if (!private)
-		return -ENODEV;
-	if (!private->ned || !private->gneq)
-		return -ENODEV;
 	uid = &private->uid;
-	spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 	memset(uid, 0, sizeof(struct dasd_uid));
 	memcpy(uid->vendor, private->ned->HDA_manufacturer,
 	       sizeof(uid->vendor) - 1);
@@ -792,6 +781,23 @@ static int dasd_eckd_generate_uid(struct dasd_device *device)
 				private->vdsneq->uit[count]);
 		}
 	}
+}
+
+/*
+ * Generate device unique id that specifies the physical device.
+ */
+static int dasd_eckd_generate_uid(struct dasd_device *device)
+{
+	struct dasd_eckd_private *private;
+	unsigned long flags;
+
+	private = (struct dasd_eckd_private *) device->private;
+	if (!private)
+		return -ENODEV;
+	if (!private->ned || !private->gneq)
+		return -ENODEV;
+	spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
+	create_uid(private);
 	spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 	return 0;
 }
@@ -811,6 +817,21 @@ static int dasd_eckd_get_uid(struct dasd_device *device, struct dasd_uid *uid)
 	return -EINVAL;
 }
 
+/*
+ * compare device UID with data of a given dasd_eckd_private structure
+ * return 0 for match
+ */
+static int dasd_eckd_compare_path_uid(struct dasd_device *device,
+				      struct dasd_eckd_private *private)
+{
+	struct dasd_uid device_uid;
+
+	create_uid(private);
+	dasd_eckd_get_uid(device, &device_uid);
+
+	return memcmp(&device_uid, &private->uid, sizeof(struct dasd_uid));
+}
+
 static void dasd_eckd_fill_rcd_cqr(struct dasd_device *device,
 				   struct dasd_ccw_req *cqr,
 				   __u8 *rcd_buffer,
@@ -1005,17 +1026,19 @@ static int dasd_eckd_read_conf(struct dasd_device *device)
 	int conf_len, conf_data_saved;
 	int rc;
 	__u8 lpm, opm;
-	struct dasd_eckd_private *private;
+	struct dasd_eckd_private *private, path_private;
 	struct dasd_path *path_data;
+	struct dasd_uid *uid;
+	char print_path_uid[60], print_device_uid[60];
 
 	private = (struct dasd_eckd_private *) device->private;
 	path_data = &device->path_data;
 	opm = ccw_device_get_path_mask(device->cdev);
-	lpm = 0x80;
 	conf_data_saved = 0;
 	/* get configuration data per operational path */
 	for (lpm = 0x80; lpm; lpm>>= 1) {
-		if (lpm & opm) {
+		if (!(lpm & opm))
+			continue;
 		rc = dasd_eckd_read_conf_lpm(device, &conf_data,
 					     &conf_len, lpm);
 		if (rc && rc != -EOPNOTSUPP) {	/* -EOPNOTSUPP is ok */
@@ -1043,7 +1066,65 @@ static int dasd_eckd_read_conf(struct dasd_device *device)
 				kfree(conf_data);
 				continue;
 			}
+			/*
+			 * build device UID that other path data
+			 * can be compared to it
+			 */
+			dasd_eckd_generate_uid(device);
 			conf_data_saved++;
+		} else {
+			path_private.conf_data = conf_data;
+			path_private.conf_len = DASD_ECKD_RCD_DATA_SIZE;
+			if (dasd_eckd_identify_conf_parts(
+				    &path_private)) {
+				path_private.conf_data = NULL;
+				path_private.conf_len = 0;
+				kfree(conf_data);
+				continue;
+			}
+
+			if (dasd_eckd_compare_path_uid(
+				    device, &path_private)) {
+				uid = &path_private.uid;
+				if (strlen(uid->vduit) > 0)
+					snprintf(print_path_uid,
+						 sizeof(print_path_uid),
+						 "%s.%s.%04x.%02x.%s",
+						 uid->vendor, uid->serial,
+						 uid->ssid, uid->real_unit_addr,
+						 uid->vduit);
+				else
+					snprintf(print_path_uid,
+						 sizeof(print_path_uid),
+						 "%s.%s.%04x.%02x",
+						 uid->vendor, uid->serial,
+						 uid->ssid,
+						 uid->real_unit_addr);
+				uid = &private->uid;
+				if (strlen(uid->vduit) > 0)
+					snprintf(print_device_uid,
+						 sizeof(print_device_uid),
+						 "%s.%s.%04x.%02x.%s",
+						 uid->vendor, uid->serial,
+						 uid->ssid, uid->real_unit_addr,
+						 uid->vduit);
+				else
+					snprintf(print_device_uid,
+						 sizeof(print_device_uid),
+						 "%s.%s.%04x.%02x",
+						 uid->vendor, uid->serial,
+						 uid->ssid,
+						 uid->real_unit_addr);
+				dev_err(&device->cdev->dev,
+					"Not all channel paths lead to "
+					"the same device, path %02X leads to "
+					"device %s instead of %s\n", lpm,
+					print_path_uid, print_device_uid);
+				return -EINVAL;
+			}
+
+			path_private.conf_data = NULL;
+			path_private.conf_len = 0;
 		}
 		switch (dasd_eckd_path_access(conf_data, conf_len)) {
 		case 0x02:
@@ -1054,10 +1135,11 @@ static int dasd_eckd_read_conf(struct dasd_device *device)
 			break;
 		}
 		path_data->opm |= lpm;
+
 		if (conf_data != private->conf_data)
 			kfree(conf_data);
 	}
-	}
+
 	return 0;
 }
 
@@ -1090,12 +1172,61 @@ static int verify_fcx_max_data(struct dasd_device *device, __u8 lpm)
 	return 0;
 }
 
+static int rebuild_device_uid(struct dasd_device *device,
+			      struct path_verification_work_data *data)
+{
+	struct dasd_eckd_private *private;
+	struct dasd_path *path_data;
+	__u8 lpm, opm;
+	int rc;
+
+	rc = -ENODEV;
+	private = (struct dasd_eckd_private *) device->private;
+	path_data = &device->path_data;
+	opm = device->path_data.opm;
+
+	for (lpm = 0x80; lpm; lpm >>= 1) {
+		if (!(lpm & opm))
+			continue;
+		memset(&data->rcd_buffer, 0, sizeof(data->rcd_buffer));
+		memset(&data->cqr, 0, sizeof(data->cqr));
+		data->cqr.cpaddr = &data->ccw;
+		rc = dasd_eckd_read_conf_immediately(device, &data->cqr,
+						     data->rcd_buffer,
+						     lpm);
+
+		if (rc) {
+			if (rc == -EOPNOTSUPP) /* -EOPNOTSUPP is ok */
+				continue;
+			DBF_EVENT_DEVID(DBF_WARNING, device->cdev,
+					"Read configuration data "
+					"returned error %d", rc);
+			break;
+		}
+		memcpy(private->conf_data, data->rcd_buffer,
+		       DASD_ECKD_RCD_DATA_SIZE);
+		if (dasd_eckd_identify_conf_parts(private)) {
+			rc = -ENODEV;
+		} else /* first valid path is enough */
+			break;
+	}
+
+	if (!rc)
+		rc = dasd_eckd_generate_uid(device);
+
+	return rc;
+}
+
 static void do_path_verification_work(struct work_struct *work)
 {
 	struct path_verification_work_data *data;
 	struct dasd_device *device;
+	struct dasd_eckd_private path_private;
+	struct dasd_uid *uid;
+	__u8 path_rcd_buf[DASD_ECKD_RCD_DATA_SIZE];
 	__u8 lpm, opm, npm, ppm, epm;
 	unsigned long flags;
+	char print_uid[60];
 	int rc;
 
 	data = container_of(work, struct path_verification_work_data, worker);
@@ -1112,8 +1243,9 @@ static void do_path_verification_work(struct work_struct *work)
 	ppm = 0;
 	epm = 0;
 	for (lpm = 0x80; lpm; lpm >>= 1) {
-		if (lpm & data->tbvpm) {
-			memset(data->rcd_buffer, 0, sizeof(data->rcd_buffer));
+		if (!(lpm & data->tbvpm))
+			continue;
+		memset(&data->rcd_buffer, 0, sizeof(data->rcd_buffer));
 		memset(&data->cqr, 0, sizeof(data->cqr));
 		data->cqr.cpaddr = &data->ccw;
 		rc = dasd_eckd_read_conf_immediately(device, &data->cqr,
@@ -1121,7 +1253,8 @@ static void do_path_verification_work(struct work_struct *work)
 						     lpm);
 		if (!rc) {
 			switch (dasd_eckd_path_access(data->rcd_buffer,
-						     DASD_ECKD_RCD_DATA_SIZE)) {
+						      DASD_ECKD_RCD_DATA_SIZE)
+				) {
 			case 0x02:
 				npm |= lpm;
 				break;
@@ -1150,9 +1283,71 @@ static void do_path_verification_work(struct work_struct *work)
 			opm &= ~lpm;
 			npm &= ~lpm;
 			ppm &= ~lpm;
+			continue;
+		}
+
+		/*
+		 * save conf_data for comparison after
+		 * rebuild_device_uid may have changed
+		 * the original data
+		 */
+		memcpy(&path_rcd_buf, data->rcd_buffer,
+		       DASD_ECKD_RCD_DATA_SIZE);
+		path_private.conf_data = (void *) &path_rcd_buf;
+		path_private.conf_len = DASD_ECKD_RCD_DATA_SIZE;
+		if (dasd_eckd_identify_conf_parts(&path_private)) {
+			path_private.conf_data = NULL;
+			path_private.conf_len = 0;
+			continue;
 		}
+
+		/*
+		 * compare path UID with device UID only if at least
+		 * one valid path is left
+		 * in other case the device UID may have changed and
+		 * the first working path UID will be used as device UID
+		 */
+		if (device->path_data.opm &&
+		    dasd_eckd_compare_path_uid(device, &path_private)) {
+			/*
+			 * the comparison was not successful
+			 * rebuild the device UID with at least one
+			 * known path in case a z/VM hyperswap command
+			 * has changed the device
+			 *
+			 * after this compare again
+			 *
+			 * if either the rebuild or the recompare fails
+			 * the path can not be used
+			 */
+			if (rebuild_device_uid(device, data) ||
+			    dasd_eckd_compare_path_uid(
+				    device, &path_private)) {
+				uid = &path_private.uid;
+				if (strlen(uid->vduit) > 0)
+					snprintf(print_uid, sizeof(print_uid),
+						 "%s.%s.%04x.%02x.%s",
+						 uid->vendor, uid->serial,
+						 uid->ssid, uid->real_unit_addr,
+						 uid->vduit);
+				else
+					snprintf(print_uid, sizeof(print_uid),
+						 "%s.%s.%04x.%02x",
+						 uid->vendor, uid->serial,
+						 uid->ssid,
+						 uid->real_unit_addr);
+				dev_err(&device->cdev->dev,
+					"The newly added channel path %02X "
+					"will not be used because it leads "
+					"to a different device %s\n",
+					lpm, print_uid);
+				opm &= ~lpm;
+				npm &= ~lpm;
+				ppm &= ~lpm;
+				continue;
 			}
 		}
+
 		/*
 		 * There is a small chance that a path is lost again between
 		 * above path verification and the following modification of
@@ -1170,6 +1365,7 @@ static void do_path_verification_work(struct work_struct *work)
 		device->path_data.ppm |= ppm;
 		device->path_data.tbvpm |= epm;
 		spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
+	}
 
 	dasd_put_device(device);
 	if (data->isglobal)
@@ -1441,11 +1637,6 @@ dasd_eckd_check_characteristics(struct dasd_device *device)
 			device->default_expires = value;
 	}
 
-	/* Generate device unique id */
-	rc = dasd_eckd_generate_uid(device);
-	if (rc)
-		goto out_err1;
-
 	dasd_eckd_get_uid(device, &temp_uid);
 	if (temp_uid.type == UA_BASE_DEVICE) {
 		block = dasd_alloc_block();