[PATCH v3 11/18] ata: libata: change ata_eh_request_sense() to not set CHECK_CONDITION

[Niklas Cassel <niklas.cassel@wdc.com>]

Currently, ata_eh_request_sense() unconditionally sets the scsicmd->result
to SAM_STAT_CHECK_CONDITION.

For Command Duration Limits policy 0xD:
The device shall complete the command without error (SAM_STAT_GOOD)
with the additional sense code set to DATA CURRENTLY UNAVAILABLE.

It is perfectly fine to have sense data for a command that returned
completion without error.

In order to support for CDL policy 0xD, we have to remove this
assumption that having sense data means that the command failed
(SAM_STAT_CHECK_CONDITION).

Change ata_eh_request_sense() to not set SAM_STAT_CHECK_CONDITION,
and instead move the setting of SAM_STAT_CHECK_CONDITION to the single
caller that wants SAM_STAT_CHECK_CONDITION set, that way
ata_eh_request_sense() can be reused in a follow-up patch that adds
support for CDL policy 0xD.

The only caller of ata_eh_request_sense() is protected by:
if (!(qc->flags & ATA_QCFLAG_SENSE_VALID)), so we can remove this
duplicated check from ata_eh_request_sense() itself.

Additionally, ata_eh_request_sense() is only called from
ata_eh_analyze_tf(), which is only called when iteratating the QCs using
ata_qc_for_each_raw(), which does not include the internal tag,
so cmd can never be NULL (all non-internal commands have qc->scsicmd set),
so remove the !cmd check as well.

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
---
 drivers/ata/libata-eh.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index a6c901811802..598ae07195b6 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1401,8 +1401,11 @@ unsigned int atapi_eh_tur(struct ata_device *dev, u8 *r_sense_key)
  *
  *	LOCKING:
  *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	true if sense data could be fetched, false otherwise.
  */
-static void ata_eh_request_sense(struct ata_queued_cmd *qc)
+static bool ata_eh_request_sense(struct ata_queued_cmd *qc)
 {
 	struct scsi_cmnd *cmd = qc->scsicmd;
 	struct ata_device *dev = qc->dev;
@@ -1411,15 +1414,12 @@ static void ata_eh_request_sense(struct ata_queued_cmd *qc)
 
 	if (ata_port_is_frozen(qc->ap)) {
 		ata_dev_warn(dev, "sense data available but port frozen\n");
-		return;
+		return false;
 	}
 
-	if (!cmd || qc->flags & ATA_QCFLAG_SENSE_VALID)
-		return;
-
 	if (!ata_id_sense_reporting_enabled(dev->id)) {
 		ata_dev_warn(qc->dev, "sense data reporting disabled\n");
-		return;
+		return false;
 	}
 
 	ata_tf_init(dev, &tf);
@@ -1432,13 +1432,19 @@ static void ata_eh_request_sense(struct ata_queued_cmd *qc)
 	/* Ignore err_mask; ATA_ERR might be set */
 	if (tf.status & ATA_SENSE) {
 		if (ata_scsi_sense_is_valid(tf.lbah, tf.lbam, tf.lbal)) {
-			ata_scsi_set_sense(dev, cmd, tf.lbah, tf.lbam, tf.lbal);
+			/* Set sense without also setting scsicmd->result */
+			scsi_build_sense_buffer(dev->flags & ATA_DFLAG_D_SENSE,
+						cmd->sense_buffer, tf.lbah,
+						tf.lbam, tf.lbal);
 			qc->flags |= ATA_QCFLAG_SENSE_VALID;
+			return true;
 		}
 	} else {
 		ata_dev_warn(dev, "request sense failed stat %02x emask %x\n",
 			     tf.status, err_mask);
 	}
+
+	return false;
 }
 
 /**
@@ -1588,8 +1594,9 @@ static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc)
 		 *  was not included in the NCQ command error log
 		 *  (i.e. NCQ autosense is not supported by the device).
 		 */
-		if (!(qc->flags & ATA_QCFLAG_SENSE_VALID) && (stat & ATA_SENSE))
-			ata_eh_request_sense(qc);
+		if (!(qc->flags & ATA_QCFLAG_SENSE_VALID) &&
+		    (stat & ATA_SENSE) && ata_eh_request_sense(qc))
+			set_status_byte(qc->scsicmd, SAM_STAT_CHECK_CONDITION);
 		if (err & ATA_ICRC)
 			qc->err_mask |= AC_ERR_ATA_BUS;
 		if (err & (ATA_UNC | ATA_AMNF))
-- 
2.39.1