3.16.51-rc1 review patch. If anyone has any objections, please let me know.
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From: Steffen Maier maier@linux.vnet.ibm.com
commit fdb7cee3b9e3c561502e58137a837341f10cbf8b upstream.
At the default trace level, we only trace unsuccessful events including FSF responses.
zfcp_dbf_hba_fsf_response() only used protocol status and FSF status to decide on an unsuccessful response. However, this is only one of multiple possible sources determining a failed struct zfcp_fsf_req.
An FSF request can also "fail" if its response runs into an ERP timeout or if it gets dismissed because a higher level recovery was triggered [trace tags "erscf_1" or "erscf_2" in zfcp_erp_strategy_check_fsfreq()]. FSF requests with ERP timeout are: FSF_QTCB_EXCHANGE_CONFIG_DATA, FSF_QTCB_EXCHANGE_PORT_DATA, FSF_QTCB_OPEN_PORT_WITH_DID or FSF_QTCB_CLOSE_PORT or FSF_QTCB_CLOSE_PHYSICAL_PORT for target ports, FSF_QTCB_OPEN_LUN, FSF_QTCB_CLOSE_LUN. One example is slow queue processing which can cause follow-on errors, e.g. FSF_PORT_ALREADY_OPEN after FSF_QTCB_OPEN_PORT_WITH_DID timed out. In order to see the root cause, we need to see late responses even if the channel presented them successfully with FSF_PROT_GOOD and FSF_GOOD. Example trace records formatted with zfcpdbf from the s390-tools package:
Timestamp : ... Area : REC Subarea : 00 Level : 1 Exception : - CPU ID : .. Caller : ... Record ID : 1 Tag : fcegpf1 LUN : 0xffffffffffffffff WWPN : 0x<WWPN> D_ID : 0x00<D_ID> Adapter status : 0x5400050b Port status : 0x41200000 LUN status : 0x00000000 Ready count : 0x00000001 Running count : 0x... ERP want : 0x02 ZFCP_ERP_ACTION_REOPEN_PORT ERP need : 0x02 ZFCP_ERP_ACTION_REOPEN_PORT | Timestamp : ... 30 seconds later Area : REC Subarea : 00 Level : 1 Exception : - CPU ID : .. Caller : ... Record ID : 2 Tag : erscf_2 LUN : 0xffffffffffffffff WWPN : 0x<WWPN> D_ID : 0x00<D_ID> Adapter status : 0x5400050b Port status : 0x41200000 LUN status : 0x00000000 Request ID : 0x<request_ID> ERP status : 0x10000000 ZFCP_STATUS_ERP_TIMEDOUT ERP step : 0x0800 ZFCP_ERP_STEP_PORT_OPENING ERP action : 0x02 ZFCP_ERP_ACTION_REOPEN_PORT ERP count : 0x00 | Timestamp : ... later than previous record Area : HBA Subarea : 00 Level : 5 > default level => 3 <= default level Exception : - CPU ID : 00 Caller : ... Record ID : 1 Tag : fs_qtcb => fs_rerr Request ID : 0x<request_ID> Request status : 0x00001010 ZFCP_STATUS_FSFREQ_DISMISSED | ZFCP_STATUS_FSFREQ_CLEANUP FSF cmnd : 0x00000005 FSF sequence no: 0x... FSF issued : ... > 30 seconds ago FSF stat : 0x00000000 FSF_GOOD FSF stat qual : 00000000 00000000 00000000 00000000 Prot stat : 0x00000001 FSF_PROT_GOOD Prot stat qual : 00000000 00000000 00000000 00000000 Port handle : 0x... LUN handle : 0x00000000 QTCB log length: ... QTCB log info : ...
In case of problems detecting that new responses are waiting on the input queue, we sooner or later trigger adapter recovery due to an FSF request timeout (trace tag "fsrth_1"). FSF requests with FSF request timeout are: typically FSF_QTCB_ABORT_FCP_CMND; but theoretically also FSF_QTCB_EXCHANGE_CONFIG_DATA or FSF_QTCB_EXCHANGE_PORT_DATA via sysfs, FSF_QTCB_OPEN_PORT_WITH_DID or FSF_QTCB_CLOSE_PORT for WKA ports, FSF_QTCB_FCP_CMND for task management function (LUN / target reset). One or more pending requests can meanwhile have FSF_PROT_GOOD and FSF_GOOD because the channel filled in the response via DMA into the request's QTCB.
In a theroretical case, inject code can create an erroneous FSF request on purpose. If data router is enabled, it uses deferred error reporting. A READ SCSI command can succeed with FSF_PROT_GOOD, FSF_GOOD, and SAM_STAT_GOOD. But on writing the read data to host memory via DMA, it can still fail, e.g. if an intentionally wrong scatter list does not provide enough space. Rather than getting an unsuccessful response, we get a QDIO activate check which in turn triggers adapter recovery. One or more pending requests can meanwhile have FSF_PROT_GOOD and FSF_GOOD because the channel filled in the response via DMA into the request's QTCB. Example trace records formatted with zfcpdbf from the s390-tools package:
Timestamp : ... Area : HBA Subarea : 00 Level : 6 > default level => 3 <= default level Exception : - CPU ID : .. Caller : ... Record ID : 1 Tag : fs_norm => fs_rerr Request ID : 0x<request_ID2> Request status : 0x00001010 ZFCP_STATUS_FSFREQ_DISMISSED | ZFCP_STATUS_FSFREQ_CLEANUP FSF cmnd : 0x00000001 FSF sequence no: 0x... FSF issued : ... FSF stat : 0x00000000 FSF_GOOD FSF stat qual : 00000000 00000000 00000000 00000000 Prot stat : 0x00000001 FSF_PROT_GOOD Prot stat qual : ........ ........ 00000000 00000000 Port handle : 0x... LUN handle : 0x... | Timestamp : ... Area : SCSI Subarea : 00 Level : 3 Exception : - CPU ID : .. Caller : ... Record ID : 1 Tag : rsl_err Request ID : 0x<request_ID2> SCSI ID : 0x... SCSI LUN : 0x... SCSI result : 0x000e0000 DID_TRANSPORT_DISRUPTED SCSI retries : 0x00 SCSI allowed : 0x05 SCSI scribble : 0x<request_ID2> SCSI opcode : 28... Read(10) FCP rsp inf cod: 0x00 FCP rsp IU : 00000000 00000000 00000000 00000000 ^^ SAM_STAT_GOOD 00000000 00000000
Only with luck in both above cases, we could see a follow-on trace record of an unsuccesful event following a successful but late FSF response with FSF_PROT_GOOD and FSF_GOOD. Typically this was the case for I/O requests resulting in a SCSI trace record "rsl_err" with DID_TRANSPORT_DISRUPTED [On ZFCP_STATUS_FSFREQ_DISMISSED, zfcp_fsf_protstatus_eval() sets ZFCP_STATUS_FSFREQ_ERROR seen by the request handler functions as failure]. However, the reason for this follow-on trace was invisible because the corresponding HBA trace record was missing at the default trace level (by default hidden records with tags "fs_norm", "fs_qtcb", or "fs_open").
On adapter recovery, after we had shut down the QDIO queues, we perform unsuccessful pseudo completions with flag ZFCP_STATUS_FSFREQ_DISMISSED for each pending FSF request in zfcp_fsf_req_dismiss_all(). In order to find the root cause, we need to see all pseudo responses even if the channel presented them successfully with FSF_PROT_GOOD and FSF_GOOD.
Therefore, check zfcp_fsf_req.status for ZFCP_STATUS_FSFREQ_DISMISSED or ZFCP_STATUS_FSFREQ_ERROR and trace with a new tag "fs_rerr".
It does not matter that there are numerous places which set ZFCP_STATUS_FSFREQ_ERROR after the location where we trace an FSF response early. These cases are based on protocol status != FSF_PROT_GOOD or == FSF_PROT_FSF_STATUS_PRESENTED and are thus already traced by default as trace tag "fs_perr" or "fs_ferr" respectively.
NB: The trace record with tag "fssrh_1" for status read buffers on dismiss all remains. zfcp_fsf_req_complete() handles this and returns early. All other FSF request types are handled separately and as described above.
Signed-off-by: Steffen Maier maier@linux.vnet.ibm.com Fixes: 8a36e4532ea1 ("[SCSI] zfcp: enhancement of zfcp debug features") Fixes: 2e261af84cdb ("[SCSI] zfcp: Only collect FSF/HBA debug data for matching trace levels") Reviewed-by: Benjamin Block bblock@linux.vnet.ibm.com Signed-off-by: Benjamin Block bblock@linux.vnet.ibm.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/s390/scsi/zfcp_dbf.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/s390/scsi/zfcp_dbf.h +++ b/drivers/s390/scsi/zfcp_dbf.h @@ -323,7 +323,11 @@ void zfcp_dbf_hba_fsf_response(struct zf { struct fsf_qtcb *qtcb = req->qtcb;
- if ((qtcb->prefix.prot_status != FSF_PROT_GOOD) && + if (unlikely(req->status & (ZFCP_STATUS_FSFREQ_DISMISSED | + ZFCP_STATUS_FSFREQ_ERROR))) { + zfcp_dbf_hba_fsf_resp("fs_rerr", 3, req); + + } else if ((qtcb->prefix.prot_status != FSF_PROT_GOOD) && (qtcb->prefix.prot_status != FSF_PROT_FSF_STATUS_PRESENTED)) { zfcp_dbf_hba_fsf_resp("fs_perr", 1, req);