From e0b870123cafde3b82cfa147f78e1e9dbec46e16 Mon Sep 17 00:00:00 2001 From: Steffen Maier Date: Wed, 10 Aug 2016 18:30:46 +0200 Subject: [PATCH] zfcp: close window with unblocked rport during rport gone commit 4eeaa4f3f1d6c47b69f70e222297a4df4743363e upstream. On a successful end of reopen port forced, zfcp_erp_strategy_followup_success() re-uses the port erp_action and the subsequent zfcp_erp_action_cleanup() now sees ZFCP_ERP_SUCCEEDED with erp_action->action==ZFCP_ERP_ACTION_REOPEN_PORT instead of ZFCP_ERP_ACTION_REOPEN_PORT_FORCED but must not perform zfcp_scsi_schedule_rport_register(). We can detect this because the fresh port reopen erp_action is in its very first step ZFCP_ERP_STEP_UNINITIALIZED. Otherwise this opens a time window with unblocked rport (until the followup port reopen recovery would block it again). If a scsi_cmnd timeout occurs during this time window fc_timed_out() cannot work as desired and such command would indeed time out and trigger scsi_eh. This prevents a clean and timely path failover. This should not happen if the path issue can be recovered on FC transport layer such as path issues involving RSCNs. Also, unnecessary and repeated DID_IMM_RETRY for pending and undesired new requests occur because internally zfcp still has its zfcp_port blocked. As follow-on errors with scsi_eh, it can cause, in the worst case, permanently lost paths due to one of: sd : [] Medium access timeout failure. Offlining disk! sd : Device offlined - not ready after error recovery For fix validation and to aid future debugging with other recoveries we now also trace (un)blocking of rports. Signed-off-by: Steffen Maier Fixes: 5767620c383a ("[SCSI] zfcp: Do not unblock rport from REOPEN_PORT_FORCED") Fixes: a2fa0aede07c ("[SCSI] zfcp: Block FC transport rports early on errors") Fixes: 5f852be9e11d ("[SCSI] zfcp: Fix deadlock between zfcp ERP and SCSI") Fixes: 338151e06608 ("[SCSI] zfcp: make use of fc_remote_port_delete when target port is unavailable") Fixes: 3859f6a248cb ("[PATCH] zfcp: add rports to enable scsi_add_device to work again") Reviewed-by: Benjamin Block Reviewed-by: Hannes Reinecke Signed-off-by: Martin K. Petersen [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/s390/scsi/zfcp_dbf.h | 7 ++++++- drivers/s390/scsi/zfcp_erp.c | 12 +++++++++--- drivers/s390/scsi/zfcp_scsi.c | 8 +++++++- 3 files changed, 22 insertions(+), 5 deletions(-) diff --git a/drivers/s390/scsi/zfcp_dbf.h b/drivers/s390/scsi/zfcp_dbf.h index 3ac7a4b30dd9..b5afa3d01e93 100644 --- a/drivers/s390/scsi/zfcp_dbf.h +++ b/drivers/s390/scsi/zfcp_dbf.h @@ -2,7 +2,7 @@ * zfcp device driver * debug feature declarations * - * Copyright IBM Corp. 2008, 2010 + * Copyright IBM Corp. 2008, 2015 */ #ifndef ZFCP_DBF_H @@ -17,6 +17,11 @@ #define ZFCP_DBF_INVALID_LUN 0xFFFFFFFFFFFFFFFFull +enum zfcp_dbf_pseudo_erp_act_type { + ZFCP_PSEUDO_ERP_ACTION_RPORT_ADD = 0xff, + ZFCP_PSEUDO_ERP_ACTION_RPORT_DEL = 0xfe, +}; + /** * struct zfcp_dbf_rec_trigger - trace record for triggered recovery action * @ready: number of ready recovery actions diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c index 5c872708a574..723cbe3985f0 100644 --- a/drivers/s390/scsi/zfcp_erp.c +++ b/drivers/s390/scsi/zfcp_erp.c @@ -3,7 +3,7 @@ * * Error Recovery Procedures (ERP). * - * Copyright IBM Corporation 2002, 2010 + * Copyright IBM Corp. 2002, 2015 */ #define KMSG_COMPONENT "zfcp" @@ -1225,8 +1225,14 @@ static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act, int result) break; case ZFCP_ERP_ACTION_REOPEN_PORT: - if (result == ZFCP_ERP_SUCCEEDED) - zfcp_scsi_schedule_rport_register(port); + /* This switch case might also happen after a forced reopen + * was successfully done and thus overwritten with a new + * non-forced reopen at `ersfs_2'. In this case, we must not + * do the clean-up of the non-forced version. + */ + if (act->step != ZFCP_ERP_STEP_UNINITIALIZED) + if (result == ZFCP_ERP_SUCCEEDED) + zfcp_scsi_schedule_rport_register(port); /* fall through */ case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED: put_device(&port->dev); diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c index 7b353647cb90..38ee0df633a3 100644 --- a/drivers/s390/scsi/zfcp_scsi.c +++ b/drivers/s390/scsi/zfcp_scsi.c @@ -3,7 +3,7 @@ * * Interface to Linux SCSI midlayer. * - * Copyright IBM Corp. 2002, 2013 + * Copyright IBM Corp. 2002, 2015 */ #define KMSG_COMPONENT "zfcp" @@ -577,6 +577,9 @@ static void zfcp_scsi_rport_register(struct zfcp_port *port) ids.port_id = port->d_id; ids.roles = FC_RPORT_ROLE_FCP_TARGET; + zfcp_dbf_rec_trig("scpaddy", port->adapter, port, NULL, + ZFCP_PSEUDO_ERP_ACTION_RPORT_ADD, + ZFCP_PSEUDO_ERP_ACTION_RPORT_ADD); rport = fc_remote_port_add(port->adapter->scsi_host, 0, &ids); if (!rport) { dev_err(&port->adapter->ccw_device->dev, @@ -598,6 +601,9 @@ static void zfcp_scsi_rport_block(struct zfcp_port *port) struct fc_rport *rport = port->rport; if (rport) { + zfcp_dbf_rec_trig("scpdely", port->adapter, port, NULL, + ZFCP_PSEUDO_ERP_ACTION_RPORT_DEL, + ZFCP_PSEUDO_ERP_ACTION_RPORT_DEL); fc_remote_port_delete(rport); port->rport = NULL; } -- 2.39.2