linux-kernel - [PATCH 3.16 026/133] scsi: zfcp: fix passing fsf_req to SCSI trace on TMF to correlate with HBA

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Message-ID: <lsq.1511315892.99218449@decadent.org.uk>
Date:   Wed, 22 Nov 2017 01:58:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Steffen Maier" <maier@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Benjamin Block" <bblock@...ux.vnet.ibm.com>
Subject: [PATCH 3.16 026/133] scsi: zfcp: fix passing fsf_req to SCSI
 trace on TMF to correlate with HBA

3.16.51-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Steffen Maier <maier@...ux.vnet.ibm.com>

commit 9fe5d2b2fd30aa8c7827ec62cbbe6d30df4fe3e3 upstream.

Without this fix we get SCSI trace records on task management functions
which cannot be correlated to HBA trace records because all fields
related to the FSF request are empty (zero).
Also, the FCP_RSP_IU is missing as well as any sense data if available.

This was caused by v2.6.14 commit 8a36e4532ea1 ("[SCSI] zfcp: enhancement
of zfcp debug features") introducing trace records for TMFs but
hard coding NULL for a possibly existing TMF FSF request.
The scsi_cmnd scribble is also zero or unrelated for the TMF request
so it also could not lookup a suitable FSF request from there.

A broken example trace record formatted with zfcpdbf from the s390-tools
package:

Timestamp      : ...
Area           : SCSI
Subarea        : 00
Level          : 1
Exception      : -
CPU ID         : ..
Caller         : 0x...
Record ID      : 1
Tag            : lr_fail
Request ID     : 0x0000000000000000
                   ^^^^^^^^^^^^^^^^ no correlation to HBA record
SCSI ID        : 0x<scsitarget>
SCSI LUN       : 0x<scsilun>
SCSI result    : 0x000e0000
SCSI retries   : 0x00
SCSI allowed   : 0x05
SCSI scribble  : 0x0000000000000000
SCSI opcode    : 2a000017 3bb80000 08000000 00000000
FCP rsp inf cod: 0x00
                   ^^ no TMF response
FCP rsp IU     : 00000000 00000000 00000000 00000000
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 00000000 00000000
                 ^^^^^^^^^^^^^^^^^ no interesting FCP_RSP_IU
Sense len      : ...
^^^^^^^^^^^^^^^^^^^^ no sense data length
Sense info     : ...
^^^^^^^^^^^^^^^^^^^^ no sense data content, even if present

There are some true cases where we really do not have an FSF request:
"rsl_fai" from zfcp_dbf_scsi_fail_send() called for early
returns / completions in zfcp_scsi_queuecommand(),
"abrt_or", "abrt_bl", "abrt_ru", "abrt_ar" from
zfcp_scsi_eh_abort_handler() where we did not get as far,
"lr_nres", "tr_nres" from zfcp_task_mgmt_function() where we're
successful and do not need to do anything because adapter stopped.
For these cases it's correct to pass NULL for fsf_req to _zfcp_dbf_scsi().

Signed-off-by: Steffen Maier <maier@...ux.vnet.ibm.com>
Fixes: 8a36e4532ea1 ("[SCSI] zfcp: enhancement of zfcp debug features")
Reviewed-by: Benjamin Block <bblock@...ux.vnet.ibm.com>
Signed-off-by: Benjamin Block <bblock@...ux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/s390/scsi/zfcp_dbf.h  | 7 ++++---
 drivers/s390/scsi/zfcp_scsi.c | 8 ++++----
 2 files changed, 8 insertions(+), 7 deletions(-)

--- 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, 2016
+ * Copyright IBM Corp. 2008, 2017
  */
 
 #ifndef ZFCP_DBF_H
@@ -401,7 +401,8 @@ void zfcp_dbf_scsi_abort(char *tag, stru
  * @flag: indicates type of reset (Target Reset, Logical Unit Reset)
  */
 static inline
-void zfcp_dbf_scsi_devreset(char *tag, struct scsi_cmnd *scmnd, u8 flag)
+void zfcp_dbf_scsi_devreset(char *tag, struct scsi_cmnd *scmnd, u8 flag,
+			    struct zfcp_fsf_req *fsf_req)
 {
 	char tmp_tag[ZFCP_DBF_TAG_LEN];
 
@@ -411,7 +412,7 @@ void zfcp_dbf_scsi_devreset(char *tag, s
 		memcpy(tmp_tag, "lr_", 3);
 
 	memcpy(&tmp_tag[3], tag, 4);
-	_zfcp_dbf_scsi(tmp_tag, 1, scmnd, NULL);
+	_zfcp_dbf_scsi(tmp_tag, 1, scmnd, fsf_req);
 }
 
 /**
--- 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, 2016
+ * Copyright IBM Corp. 2002, 2017
  */
 
 #define KMSG_COMPONENT "zfcp"
@@ -299,7 +299,7 @@ static int zfcp_task_mgmt_function(struc
 
 		if (!(atomic_read(&adapter->status) &
 		      ZFCP_STATUS_COMMON_RUNNING)) {
-			zfcp_dbf_scsi_devreset("nres", scpnt, tm_flags);
+			zfcp_dbf_scsi_devreset("nres", scpnt, tm_flags, NULL);
 			return SUCCESS;
 		}
 	}
@@ -309,10 +309,10 @@ static int zfcp_task_mgmt_function(struc
 	wait_for_completion(&fsf_req->completion);
 
 	if (fsf_req->status & ZFCP_STATUS_FSFREQ_TMFUNCFAILED) {
-		zfcp_dbf_scsi_devreset("fail", scpnt, tm_flags);
+		zfcp_dbf_scsi_devreset("fail", scpnt, tm_flags, fsf_req);
 		retval = FAILED;
 	} else {
-		zfcp_dbf_scsi_devreset("okay", scpnt, tm_flags);
+		zfcp_dbf_scsi_devreset("okay", scpnt, tm_flags, fsf_req);
 		zfcp_scsi_forget_cmnds(zfcp_sdev, tm_flags);
 	}