scsi: zfcp: Handle event-lost notification for Version Change events

As recovery for a lost Version Change event, trigger an Exchange Config
Data cmd to retrieve the current FW version.

Doing so requires process context (as eg. zfcp_qdio_sbal_get() might need
to sleep), so defer from tasklet context into a work item.

Link: https://lore.kernel.org/r/297c7be2944c3714863fcd22d531d910312d29f0.1603908167.git.bblock@linux.ibm.com
Suggested-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_aux.c

@@ -292,6 +292,14 @@ static void _zfcp_status_read_scheduler(struct work_struct *work)
 					     stat_work));
 }
 
+static void zfcp_version_change_lost_work(struct work_struct *work)
+{
+	struct zfcp_adapter *adapter = container_of(work, struct zfcp_adapter,
+						    version_change_lost_work);
+
+	zfcp_fsf_exchange_config_data_sync(adapter->qdio, NULL);
+}
+
 static void zfcp_print_sl(struct seq_file *m, struct service_level *sl)
 {
 	struct zfcp_adapter *adapter =
@@ -353,6 +361,8 @@ struct zfcp_adapter *zfcp_adapter_enqueue(struct ccw_device *ccw_device)
 	INIT_WORK(&adapter->stat_work, _zfcp_status_read_scheduler);
 	INIT_DELAYED_WORK(&adapter->scan_work, zfcp_fc_scan_ports);
 	INIT_WORK(&adapter->ns_up_work, zfcp_fc_sym_name_update);
+	INIT_WORK(&adapter->version_change_lost_work,
+		  zfcp_version_change_lost_work);
 
 	adapter->next_port_scan = jiffies;
 
@@ -429,6 +439,7 @@ void zfcp_adapter_unregister(struct zfcp_adapter *adapter)
 	cancel_delayed_work_sync(&adapter->scan_work);
 	cancel_work_sync(&adapter->stat_work);
 	cancel_work_sync(&adapter->ns_up_work);
+	cancel_work_sync(&adapter->version_change_lost_work);
 	zfcp_destroy_adapter_work_queue(adapter);
 
 	zfcp_fc_wka_ports_force_offline(adapter->gs);

drivers/s390/scsi/zfcp_def.h

@@ -201,6 +201,7 @@ struct zfcp_adapter {
 	struct zfcp_fc_events events;
 	unsigned long		next_port_scan;
 	struct zfcp_diag_adapter	*diagnostics;
+	struct work_struct	version_change_lost_work;
 };
 
 struct zfcp_port {

drivers/s390/scsi/zfcp_fsf.c

@@ -309,6 +309,9 @@ static void zfcp_fsf_status_read_handler(struct zfcp_fsf_req *req)
 	case FSF_STATUS_READ_NOTIFICATION_LOST:
 		if (sr_buf->status_subtype & FSF_STATUS_READ_SUB_INCOMING_ELS)
 			zfcp_fc_conditional_port_scan(adapter);
+		if (sr_buf->status_subtype & FSF_STATUS_READ_SUB_VERSION_CHANGE)
+			queue_work(adapter->work_queue,
+				   &adapter->version_change_lost_work);
 		break;
 	case FSF_STATUS_READ_FEATURE_UPDATE_ALERT:
 		adapter->adapter_features = sr_buf->payload.word[0];

drivers/s390/scsi/zfcp_fsf.h

@@ -143,6 +143,7 @@
 
 /* status subtypes for unsolicited status notification lost */
 #define FSF_STATUS_READ_SUB_INCOMING_ELS	0x00000001
+#define FSF_STATUS_READ_SUB_VERSION_CHANGE	0x00000100
 
 /* status subtypes for version change */
 #define FSF_STATUS_READ_SUB_LIC_CHANGE		0x00000001