[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 <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index c55dd2728f90..c557ba34e1aa 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/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;
         }
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index ae151390cb9f..8aab3091a7b1 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/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;