[SCSI] zfcp: fix deadlock between wq triggered port scan and ERP

Waiting for the ERP to be finished in a task running in the global
kernel work-queue is a bad idea, especially if the ERP needs to run
another job in this work-queue before it can finish. -> deadlock.

This patch removes the necessity to wait for a finished ERP from the
scan task and moves the job scheduling to the end of the ERP.

Signed-off-by: Swen Schillig <[email protected]>
Signed-off-by: Christof Schmitt <[email protected]>
Signed-off-by: James Bottomley <[email protected]>

Author: sswen

drivers/s390/scsi/zfcp_erp.c

@@ -720,7 +720,6 @@ static int zfcp_erp_adapter_strategy_generic(struct zfcp_erp_action *act,
 		goto failed_openfcp;
 
 	atomic_set_mask(ZFCP_STATUS_COMMON_OPEN, &act->adapter->status);
-	schedule_work(&act->adapter->scan_work);
 
 	return ZFCP_ERP_SUCCEEDED;
 
@@ -1284,6 +1283,8 @@ static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act, int result)
 	case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
 		if (result != ZFCP_ERP_SUCCEEDED)
 			zfcp_erp_rports_del(adapter);
+		else
+			schedule_work(&adapter->scan_work);
 		zfcp_adapter_put(adapter);
 		break;
 	}

drivers/s390/scsi/zfcp_fc.c

@@ -610,7 +610,6 @@ int zfcp_scan_ports(struct zfcp_adapter *adapter)
 	int ret, i;
 	struct zfcp_gpn_ft *gpn_ft;
 
-	zfcp_erp_wait(adapter); /* wait until adapter is finished with ERP */
 	if (fc_host_port_type(adapter->scsi_host) != FC_PORTTYPE_NPORT)
 		return 0;