On Thu, Jun 20, 2024 at 04:24:11PM +0200, Niklas Cassel wrote: > On Mon, Jun 17, 2024 at 11:31:49PM +0000, Igor Pylypiv wrote: > > On Mon, Jun 17, 2024 at 12:49:47PM +0200, Niklas Cassel wrote: > > > On Fri, Jun 14, 2024 at 07:18:34PM +0000, Igor Pylypiv wrote: > > > > Do not generate sense data from ATA status/error registers > > > > if valid sense data is already present. > > > > > > > > Signed-off-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx> > > > > --- > > > > drivers/ata/libata-scsi.c | 17 +++++++++++------ > > > > 1 file changed, 11 insertions(+), 6 deletions(-) > > > > > > > > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > > > > index 79e8103ef3a9..4bfe47e7d266 100644 > > > > --- a/drivers/ata/libata-scsi.c > > > > +++ b/drivers/ata/libata-scsi.c > > > > @@ -858,12 +858,17 @@ static void ata_gen_passthru_sense(struct ata_queued_cmd *qc) > > > > unsigned char *desc = sb + 8; > > > > u8 sense_key, asc, ascq; > > > > > > Like I suggested in the earlier patch, > > > > > > can't you do a: > > > > > > if (qc->flags & ATA_QCFLAG_SENSE_VALID) > > > return; > > > > > > here instead? > > > > > > > We need to populate the "ATA Status Return sense data descriptor" as per SAT-5 > > "Table 209 — ATA command results". By returning early we are skipping the code > > that copies ATA output fields into descriptor/fixed sense data buffer. > > We might get sense data from the drive. > If we use REQUEST SENSE DATA EXT, we will get SK/ASC/ASCQ, > we will then call scsi_build_sense_buffer() which will generate > sense data in either the descriptor format or the fixed format, > based on the D_SENSE bit, which is set in the control mode page. > > The user can toggle this bit, see: > https://github.com/torvalds/linux/blob/v6.10-rc4/drivers/ata/libata-scsi.c#L3691-L3694 > > But by default it is 0: > https://github.com/torvalds/linux/blob/v6.10-rc4/drivers/ata/libata-scsi.c#L86 > which means fixed format. > > This all seems to be in accordance with > "Table 209 — Returned sense data with the CK_COND bit set to one" > in sat6r1. > > > > When calling scsi_build_sense_buffer(), we supply: > scsi_build_sense_buffer(dev->flags & ATA_DFLAG_D_SENSE, > cmd->sense_buffer, tf.lbah, > tf.lbam, tf.lbal); > > so we do not supply the STATUS and ERROR fields when building the sense data. > > This seems fine, since SCSI has no knowledge of ATA status or ATA error. > > > However, for ATA-passthrough commands, ATA status and ATA error fields > are part of either the COMMAND-SPECIFIC information in the fixed format > case, or part for the descriptor format, in case of the descriptor type > being ATA Status Return sense data descriptor. > > > So what I think we should do: > 1) Keep the sense data if it exists, and fill in > the ATA status and ATA error at the correct offset (depending on if > the existing sense data is in fixed format or descriptor format). > 2) If there doesn't exist any sense data, generate it, including the > ATA passthru command specific fields (ATA status and ATA error). > This is basically what ata_gen_passthru_sense() does today. > Yes! That's exactly what I was trying to do with the horrible empty if in ata_gen_passthru_sense(). Factoring out ATA status and ATA error population into a separate function makes the code more readable and less error-prone. I'll make the change in v2. Thank you! Igor > > So something like this: > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > index bb4d30d377ae..a0687eb28ff7 100644 > --- a/drivers/ata/libata-scsi.c > +++ b/drivers/ata/libata-scsi.c > @@ -1645,9 +1645,17 @@ 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)) > - ata_gen_passthru_sense(qc); > - else if (need_sense) > + ((cdb[2] & 0x20) || need_sense)) { > + if ((qc->flags & ATA_QCFLAG_SENSE_VALID)) { > + /* > + * ATA PASS-THROUGH commands also need to fill in the > + * command specific ATA status and ATA error fields. > + */ > + ata_fill_passthru_specific_sense_fields(qc); > + } else { > + ata_gen_passthru_sense(qc); > + } > + } else if (need_sense) > ata_gen_ata_sense(qc); > else > /* Keep the SCSI ML and status byte, clear host byte. */ > > > Kind regards, > Niklas > > > >
