[PATCH v4 2/8] ata: libata-scsi: Do not overwrite valid sense data when CK_COND=1

Igor Pylypiv
2024-07-01T19:58:08Z

Current ata_gen_passthru_sense() code performs two actions:
1. Generates sense data based on the ATA 'status' and ATA 'error' fields.
2. Populates "ATA Status Return sense data descriptor" / "Fixed format
sense data" with ATA taskfile fields.

The problem is that #1 generates sense data even when a valid sense data
is already present (ATA_QCFLAG_SENSE_VALID is set). Factoring out #2 into
a separate function allows us to generate sense data only when there is
no valid sense data (ATA_QCFLAG_SENSE_VALID is not set).

As a bonus, we can now delete a FIXME comment in atapi_qc_complete()
which states that we don't want to translate taskfile registers into
sense descriptors for ATAPI.

Cc: stable@vger.kernel.org # 4.19+
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
---
drivers/ata/libata-scsi.c | 158 +++++++++++++++++++++-----------------
1 file changed, 86 insertions(+), 72 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index a9e44ad4c2de..26b1263f5c7c 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -230,6 +230,80 @@ void ata_scsi_set_sense_information(struct ata_device *dev,
SCSI_SENSE_BUFFERSIZE, information);
}

+/**
+ * ata_scsi_set_passthru_sense_fields - Set ATA fields in sense buffer
+ * @qc: ATA PASS-THROUGH command.
+ *
+ * Populates "ATA Status Return sense data descriptor" / "Fixed format
+ * sense data" with ATA taskfile fields.
+ *
+ * LOCKING:
+ * None.
+ */
+static void ata_scsi_set_passthru_sense_fields(struct ata_queued_cmd *qc)
+{
+ struct scsi_cmnd *cmd = qc->scsicmd;
+ struct ata_taskfile *tf = &qc->result_tf;
+ unsigned char *sb = cmd->sense_buffer;
+
+ if ((sb[0] & 0x7f) >= 0x72) {
+ unsigned char *desc;
+ u8 len;
+
+ /* descriptor format */
+ len = sb[7];
+ desc = (char *)scsi_sense_desc_find(sb, len + 8, 9);
+ if (!desc) {
+ if (SCSI_SENSE_BUFFERSIZE < len + 14)
+ return;
+ sb[7] = len + 14;
+ desc = sb + 8 + len;
+ }
+ desc[0] = 9;
+ desc[1] = 12;
+ /*
+ * Copy registers into sense buffer.
+ */
+ desc[2] = 0x00;
+ desc[3] = tf->error;
+ desc[5] = tf->nsect;
+ desc[7] = tf->lbal;
+ desc[9] = tf->lbam;
+ desc[11] = tf->lbah;
+ desc[12] = tf->device;
+ desc[13] = tf->status;
+
+ /*
+ * Fill in Extend bit, and the high order bytes
+ * if applicable.
+ */
+ if (tf->flags & ATA_TFLAG_LBA48) {
+ desc[2] |= 0x01;
+ desc[4] = tf->hob_nsect;
+ desc[6] = tf->hob_lbal;
+ desc[8] = tf->hob_lbam;
+ desc[10] = tf->hob_lbah;
+ }
+ } else {
+ /* Fixed sense format */
+ sb[0] |= 0x80;
+ sb[3] = tf->error;
+ sb[4] = tf->status;
+ sb[5] = tf->device;
+ sb[6] = tf->nsect;
+ if (tf->flags & ATA_TFLAG_LBA48) {
+ sb[8] |= 0x80;
+ if (tf->hob_nsect)
+ sb[8] |= 0x40;
+ if (tf->hob_lbal || tf->hob_lbam || tf->hob_lbah)
+ sb[8] |= 0x20;
+ }
+ sb[9] = tf->lbal;
+ sb[10] = tf->lbam;
+ sb[11] = tf->lbah;
+ }
+}
+
static void ata_scsi_set_invalid_field(struct ata_device *dev,
struct scsi_cmnd *cmd, u16 field, u8 bit)
{
@@ -837,10 +911,8 @@ static void ata_to_sense_error(unsigned id, u8 drv_stat, u8 drv_err, u8 *sk,
* ata_gen_passthru_sense - Generate check condition sense block.
* @qc: Command that completed.
*
- * This function is specific to the ATA descriptor format sense
- * block specified for the ATA pass through commands. Regardless
- * of whether the command errored or not, return a sense
- * block. Copy all controller registers into the sense
+ * This function is specific to the ATA pass through commands.
+ * Regardless of whether the command errored or not, return a sense
* block. If there was no error, we get the request from an ATA
* passthrough command, so we use the following sense data:
* sk = RECOVERED ERROR
@@ -875,63 +947,6 @@ static void ata_gen_passthru_sense(struct ata_queued_cmd *qc)
*/
scsi_build_sense(cmd, 1, RECOVERED_ERROR, 0, 0x1D);
}
-
- if ((sb[0] & 0x7f) >= 0x72) {
- unsigned char *desc;
- u8 len;
-
- /* descriptor format */
- len = sb[7];
- desc = (char *)scsi_sense_desc_find(sb, len + 8, 9);
- if (!desc) {
- if (SCSI_SENSE_BUFFERSIZE < len + 14)
- return;
- sb[7] = len + 14;
- desc = sb + 8 + len;
- }
- desc[0] = 9;
- desc[1] = 12;
- /*
- * Copy registers into sense buffer.
- */
- desc[2] = 0x00;
- desc[3] = tf->error;
- desc[5] = tf->nsect;
- desc[7] = tf->lbal;
- desc[9] = tf->lbam;
- desc[11] = tf->lbah;
- desc[12] = tf->device;
- desc[13] = tf->status;
-
- /*
- * Fill in Extend bit, and the high order bytes
- * if applicable.
- */
- if (tf->flags & ATA_TFLAG_LBA48) {
- desc[2] |= 0x01;
- desc[4] = tf->hob_nsect;
- desc[6] = tf->hob_lbal;
- desc[8] = tf->hob_lbam;
- desc[10] = tf->hob_lbah;
- }
- } else {
- /* Fixed sense format */
- sb[0] |= 0x80;
- sb[3] = tf->error;
- sb[4] = tf->status;
- sb[5] = tf->device;
- sb[6] = tf->nsect;
- if (tf->flags & ATA_TFLAG_LBA48) {
- sb[8] |= 0x80;
- if (tf->hob_nsect)
- sb[8] |= 0x40;
- if (tf->hob_lbal || tf->hob_lbam || tf->hob_lbah)
- sb[8] |= 0x20;
- }
- sb[9] = tf->lbal;
- sb[10] = tf->lbam;
- sb[11] = tf->lbah;
- }
}

/**
@@ -1634,6 +1649,8 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
u8 *cdb = cmd->cmnd;
int need_sense = (qc->err_mask != 0) &&
!(qc->flags & ATA_QCFLAG_SENSE_VALID);
+ int need_passthru_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
@@ -1645,13 +1662,16 @@ 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_passthru_sense)) {
+ if (!(qc->flags & ATA_QCFLAG_SENSE_VALID))
+ ata_gen_passthru_sense(qc);
+ ata_scsi_set_passthru_sense_fields(qc);
+ } else if (need_sense) {
ata_gen_ata_sense(qc);
- else
+ } else {
/* Keep the SCSI ML and status byte, clear host byte. */
cmd->result &= 0x0000ffff;
+ }

ata_qc_done(qc);
}
@@ -2590,14 +2610,8 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
/* handle completion from EH */
if (unlikely(err_mask || qc->flags & ATA_QCFLAG_SENSE_VALID)) {

- if (!(qc->flags & ATA_QCFLAG_SENSE_VALID)) {
- /* FIXME: not quite right; we don't want the
- * translation of taskfile registers into a
- * sense descriptors, since that's only
- * correct for ATA, not ATAPI
- */
+ if (!(qc->flags & ATA_QCFLAG_SENSE_VALID))
ata_gen_passthru_sense(qc);
- }

/* SCSI EH automatically locks door if sdev->locked is
* set. Sometimes door lock request continues to
--
2.45.2.803.g4e1b14247a-goog