For SCSI ML byte: In the case where a command is completed via libata EH: irq -> ata_qc_complete() -> ata_qc_schedule_eh() irq done ... -> ata_do_eh() -> ata_eh_link_autopsy() -> ata_eh_finish() -> ata_eh_qc_complete() -> __ata_eh_qc_complete() -> __ata_qc_complete() -> qc->complete_fn() (ata_scsi_qc_complete()) -> ata_qc_done() -> qc->scsidone() (empty stub) ... -> scsi_eh_finish_cmd() -> scsi_eh_flush_done_q() -> scsi_finish_command() ata_eh_link_autopsy() will call ata_eh_analyze_tf(), which calls scsi_check_sense(), which sets the SCSI ML byte. Since ata_scsi_qc_complete() is called after scsi_check_sense() when a command is completed via libata EH, we cannot simply overwrite the SCSI ML byte that was set earlier in the call chain. For SCSI status byte: When a SCSI command is prepared using scsi_prepare_cmd(), it sets cmd->result to 0. (SAM_STAT_GOOD is defined as 0x0). Likewise, when a command is requeued from SCSI EH, scsi_queue_insert() is called, which sets cmd->result to 0. A SCSI command thus always has a GOOD status by default when being sent to libata. If libata fetches sense data from the device, it will call ata_scsi_set_sense(), which will set the status byte to SAM_STAT_CHECK_CONDITION, if the caller deems that the status should be a check condition. ata_scsi_qc_complete() should therefore never overwrite the existing status byte, because if it is != GOOD, it was set by libata itself, for a reason. For the host byte: When libata abort commands, because of a NCQ error, it will schedule SCSI EH for all QCs using blk_abort_request(), which will all end up in scsi_timeout(), which will call scsi_abort_command(). scsi_timeout() sets DID_TIME_OUT regardless if a command was aborted or timed out. If we don't clear the DID_TIME_OUT byte for the QC that caused the NCQ error, we that QC will be reported as a timed out command, instead of being reported as a NCQ error. For a command that actually timed out, DID_TIME_OUT would be fine to keep, but libata has its own way of detecting that a command timed out (see ata_scsi_cmd_error_handler()), and sets AC_ERR_TIMEOUT if that is the case. libata will retry timed out commands. We could clear DID_TIME_OUT only for the QC that caused the NCQ error, but since libata has its own way of detecting timeouts, simply clear it always. Note that the existing ata_scsi_qc_complete() code does: cmd->result = SAM_STAT_CHECK_CONDITION or cmd->result = SAM_STAT_GOOD. This WILL clear the host byte. So us clearing the host byte unconditionally is in line with the existing libata behavior. Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx> --- drivers/ata/libata-scsi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index 0e6684ca0315..ca3b92a1a6a5 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -1656,7 +1656,8 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc) struct ata_port *ap = qc->ap; struct scsi_cmnd *cmd = qc->scsicmd; u8 *cdb = cmd->cmnd; - int need_sense = (qc->err_mask != 0); + int need_sense = (qc->err_mask != 0) && + !(qc->flags & ATA_QCFLAG_SENSE_VALID); /* For ATA pass thru (SAT) commands, generate a sense block if * user mandated it or if there's an error. Note that if we @@ -1670,12 +1671,11 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc) if (((cdb[0] == ATA_16) || (cdb[0] == ATA_12)) && ((cdb[2] & 0x20) || need_sense)) ata_gen_passthru_sense(qc); - else if (qc->flags & ATA_QCFLAG_SENSE_VALID) - cmd->result = SAM_STAT_CHECK_CONDITION; else if (need_sense) ata_gen_ata_sense(qc); else - cmd->result = SAM_STAT_GOOD; + /* Keep the SCSI ML and status byte, clear host byte. */ + cmd->result &= 0x0000ffff; if (need_sense && !ap->ops->error_handler) ata_dump_status(ap, &qc->result_tf); -- 2.38.1
