scsi: zfcp: fix missing SCSI trace for result of eh_host_reset_handler

For problem determination we need to see whether and why we were successful
or not. This allows deduction of scsi_eh escalation.

Example trace record formatted with zfcpdbf from s390-tools:

Timestamp      : ...
Area           : SCSI
Subarea        : 00
Level          : 1
Exception      : -
CPU ID         : ..
Caller         : 0x...
Record ID      : 1
Tag            : schrh_r        SCSI host reset handler result
Request ID     : 0x0000000000000000                     none (invalid)
SCSI ID        : 0xffffffff                             none (invalid)
SCSI LUN       : 0xffffffff                             none (invalid)
SCSI LUN high  : 0xffffffff                             none (invalid)
SCSI result    : 0x00002002     field re-used for midlayer value: SUCCESS
                                or in other cases: 0x2009 == FAST_IO_FAIL
SCSI retries   : 0xff                                   none (invalid)
SCSI allowed   : 0xff                                   none (invalid)
SCSI scribble  : 0xffffffffffffffff                     none (invalid)
SCSI opcode    : ffffffff ffffffff ffffffff ffffffff    none (invalid)
FCP rsp inf cod: 0xff                                   none (invalid)
FCP rsp IU     : 00000000 00000000 00000000 00000000    none (invalid)
                 00000000 00000000

v2.6.35 commit a1dbfddd02d2 ("[SCSI] zfcp: Pass return code from
fc_block_scsi_eh to scsi eh") introduced the first return with something
other than the previously hardcoded single SUCCESS return path.

Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Fixes: a1dbfddd02d2 ("[SCSI] zfcp: Pass return code from fc_block_scsi_eh to scsi eh")
Cc: <stable@vger.kernel.org> #2.6.38+
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_dbf.c

@@ -643,6 +643,46 @@ void zfcp_dbf_scsi(char *tag, int level, struct scsi_cmnd *sc,
 	spin_unlock_irqrestore(&dbf->scsi_lock, flags);
 }
 
+/**
+ * zfcp_dbf_scsi_eh() - Trace event for special cases of scsi_eh callbacks.
+ * @tag: Identifier for event.
+ * @adapter: Pointer to zfcp adapter as context for this event.
+ * @scsi_id: SCSI ID/target to indicate scope of task management function (TMF).
+ * @ret: Return value of calling function.
+ *
+ * This SCSI trace variant does not depend on any of:
+ * scsi_cmnd, zfcp_fsf_req, scsi_device.
+ */
+void zfcp_dbf_scsi_eh(char *tag, struct zfcp_adapter *adapter,
+		      unsigned int scsi_id, int ret)
+{
+	struct zfcp_dbf *dbf = adapter->dbf;
+	struct zfcp_dbf_scsi *rec = &dbf->scsi_buf;
+	unsigned long flags;
+	static int const level = 1;
+
+	if (unlikely(!debug_level_enabled(adapter->dbf->scsi, level)))
+		return;
+
+	spin_lock_irqsave(&dbf->scsi_lock, flags);
+	memset(rec, 0, sizeof(*rec));
+
+	memcpy(rec->tag, tag, ZFCP_DBF_TAG_LEN);
+	rec->id = ZFCP_DBF_SCSI_CMND;
+	rec->scsi_result = ret; /* re-use field, int is 4 bytes and fits */
+	rec->scsi_retries = ~0;
+	rec->scsi_allowed = ~0;
+	rec->fcp_rsp_info = ~0;
+	rec->scsi_id = scsi_id;
+	rec->scsi_lun = (u32)ZFCP_DBF_INVALID_LUN;
+	rec->scsi_lun_64_hi = (u32)(ZFCP_DBF_INVALID_LUN >> 32);
+	rec->host_scribble = ~0;
+	memset(rec->scsi_opcode, 0xff, ZFCP_DBF_SCSI_OPCODE);
+
+	debug_event(dbf->scsi, level, rec, sizeof(*rec));
+	spin_unlock_irqrestore(&dbf->scsi_lock, flags);
+}
+
 static debug_info_t *zfcp_dbf_reg(const char *name, int size, int rec_size)
 {
 	struct debug_info *d;

drivers/s390/scsi/zfcp_ext.h

@@ -49,6 +49,8 @@ extern void zfcp_dbf_san_res(char *, struct zfcp_fsf_req *);
 extern void zfcp_dbf_san_in_els(char *, struct zfcp_fsf_req *);
 extern void zfcp_dbf_scsi(char *, int, struct scsi_cmnd *,
 			  struct zfcp_fsf_req *);
+extern void zfcp_dbf_scsi_eh(char *tag, struct zfcp_adapter *adapter,
+			     unsigned int scsi_id, int ret);
 
 /* zfcp_erp.c */
 extern void zfcp_erp_set_adapter_status(struct zfcp_adapter *, u32);

drivers/s390/scsi/zfcp_scsi.c

@@ -323,15 +323,16 @@ static int zfcp_scsi_eh_host_reset_handler(struct scsi_cmnd *scpnt)
 {
 	struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(scpnt->device);
 	struct zfcp_adapter *adapter = zfcp_sdev->port->adapter;
-	int ret;
+	int ret = SUCCESS, fc_ret;
 
 	zfcp_erp_adapter_reopen(adapter, 0, "schrh_1");
 	zfcp_erp_wait(adapter);
-	ret = fc_block_scsi_eh(scpnt);
-	if (ret)
-		return ret;
+	fc_ret = fc_block_scsi_eh(scpnt);
+	if (fc_ret)
+		ret = fc_ret;
 
-	return SUCCESS;
+	zfcp_dbf_scsi_eh("schrh_r", adapter, ~0, ret);
+	return ret;
 }
 
 struct scsi_transport_template *zfcp_scsi_transport_template;