On Fri, Jun 14, 2024 at 07:18:33PM +0000, Igor Pylypiv wrote: > SCSI/ATA Translation-5 (SAT-5) Table 209 — "ATA command results" > specifies that SATL shall generate sense data for ATA PASS-THROUGH > commands when either CK_COND is set or when ATA_ERR or ATA_DF status > bits are set. > > ata_eh_analyze_tf() sets AC_ERR_DEV bit in qc->err_mask when ATA_ERR > or ATA_DF bits are set. It looks like qc->err_mask can be used as > an error indicator but ata_eh_link_autopsy() clears AC_ERR_DEV bit > when ATA_QCFLAG_SENSE_VALID is set. This effectively clears the error > indication if no other bits were set in qc->err_mask. The reason why libata clears the err_mask when having sense data, is because the upper layer, i.e. SCSI, should determine what to do with the command, if there is sense data. For a non-passthrough command, this will be done by scsi_io_completion_action(): https://github.com/torvalds/linux/blob/v6.10-rc4/drivers/scsi/scsi_lib.c#L1084-L1087 However, if there is any bits set in cmd->result, scsi_io_completion_nz_result() will be called: https://github.com/torvalds/linux/blob/v6.10-rc4/drivers/scsi/scsi_lib.c#L1052-L1053 which will do the following for a passthrough command: https://github.com/torvalds/linux/blob/v6.10-rc4/drivers/scsi/scsi_lib.c#L969-L978 which will set blk_stat. After that, scsi_io_completion() which check blk_stat and if it is a scsi_noretry_cmd(): https://github.com/torvalds/linux/blob/v6.10-rc4/drivers/scsi/scsi_lib.c#L1073-L1078 A passthrough command will return true for scsi_noretry_cmd(), so scsi_io_completion_action() should NOT get called for a passthough command. So IIUC, for a non-passthrough command, scsi_io_completion_action() will decide what to do depending on the sense data, but a passthrough command will get finished with the sense data, leaving the user to decide what to do. > > ata_scsi_qc_complete() should not use qc->err_mask for ATA PASS-THROUGH > commands because qc->err_mask can be zero (i.e. "no error") even when > the corresponding command has failed with ATA_ERR/ATA_DF bits set. > > Additionally, the presence of valid sense data (ATA_QCFLAG_SENSE_VALID) > should not prevent SATL from generating sense data for ATA PASS-THROUGH. > > Signed-off-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx> > --- > drivers/ata/libata-scsi.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > index 032cf11d0bcc..79e8103ef3a9 100644 > --- a/drivers/ata/libata-scsi.c > +++ b/drivers/ata/libata-scsi.c > @@ -1632,8 +1632,8 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc) > !(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 > - * generate because the user forced us to [CK_COND =1], a check > + * user mandated it or if ATA_ERR or ATA_DF bits are set. Note that > + * if we generate because the user forced us to [CK_COND=1], a check > * condition is generated and the ATA register values are returned > * whether the command completed successfully or not. If there > * was no error, we use the following sense data: > @@ -1641,7 +1641,7 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc) > * asc,ascq = ATA PASS-THROUGH INFORMATION AVAILABLE > */ > if (((cdb[0] == ATA_16) || (cdb[0] == ATA_12)) && > - ((cdb[2] & 0x20) || need_sense)) > + ((cdb[2] & 0x20) || (qc->result_tf.status & (ATA_ERR | ATA_DF)))) qc->result_tf can only be used if qc->flags has ATA_QCFLAG_RESULT_TF set, otherwise it can contain bogus data. You don't seem to check if ATA_QCFLAG_RESULT_TF is set. ata_scsi_pass_thru() does set ATA_QCFLAG_RESULT_TF. > ata_gen_passthru_sense(qc); > else if (need_sense) > ata_gen_ata_sense(qc); > -- > 2.45.2.627.g7a2c4fd464-goog >
