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ata: libata-scsi: Do not overwrite valid sense data when CK_COND=1
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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.

Additionally, always set SAM_STAT_CHECK_CONDITION when CK_COND=1 because
SAT specification mandates that SATL shall return CHECK CONDITION if
the CK_COND bit is set.

The ATA PASS-THROUGH handling logic in ata_scsi_qc_complete() is hard
to read/understand. Improve the readability of the code by moving checks
into self-explanatory boolean variables.

Cc: stable@vger.kernel.org # 4.19+
Co-developed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
Link: https://lore.kernel.org/r/20240702024735.1152293-3-ipylypiv@google.com
Signed-off-by: Niklas Cassel <cassel@kernel.org>
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ipylypiv authored and Niklas Cassel committed Jul 3, 2024
1 parent 38dab83 commit 9798192
Showing 1 changed file with 92 additions and 77 deletions.
169 changes: 92 additions & 77 deletions drivers/ata/libata-scsi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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;
}
}

/**
Expand Down Expand Up @@ -1632,26 +1647,32 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
{
struct scsi_cmnd *cmd = qc->scsicmd;
u8 *cdb = cmd->cmnd;
int need_sense = (qc->err_mask != 0) &&
!(qc->flags & ATA_QCFLAG_SENSE_VALID);
bool have_sense = qc->flags & ATA_QCFLAG_SENSE_VALID;
bool is_ata_passthru = cdb[0] == ATA_16 || cdb[0] == ATA_12;
bool is_ck_cond_request = cdb[2] & 0x20;
bool is_error = qc->err_mask != 0;

/* 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
* 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:
* was no error, and CK_COND=1, we use the following sense data:
* sk = RECOVERED ERROR
* 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)
if (is_ata_passthru && (is_ck_cond_request || is_error || have_sense)) {
if (!have_sense)
ata_gen_passthru_sense(qc);
ata_scsi_set_passthru_sense_fields(qc);
if (is_ck_cond_request)
set_status_byte(qc->scsicmd, SAM_STAT_CHECK_CONDITION);
} else if (is_error && !have_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);
}
Expand Down Expand Up @@ -2590,14 +2611,8 @@ 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
Expand Down

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