[PATCH] libata: don't request sense data on !ZAC ATA devices

From: Tejun Heo <tj@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-ide@vger.kernel.org, Hannes Reinecke <hare@kernel.org>,
	kernel-team@fb.com
Subject: [PATCH] libata: don't request sense data on !ZAC ATA devices
Date: Mon, 24 Jun 2019 09:32:50 -0700	[thread overview]
Message-ID: <20190624163250.GP657710@devbig004.ftw2.facebook.com> (raw)

ZAC support added sense data requesting on error for both ZAC and ATA
devices. This seems to cause erratic error handling behaviors on some
SSDs where the device reports sense data availability and then
delivers the wrong content making EH take the wrong actions.  The
failure mode was sporadic on a LITE-ON ssd and couldn't be reliably
reproduced.

There is no value in requesting sense data from non-ZAC ATA devices
while there's a significant risk of introducing EH misbehaviors which
are difficult to reproduce and fix.  Let's do the sense data dancing
only for ZAC devices.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Hannes Reinecke <hare@kernel.org>
---
 drivers/ata/libata-eh.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 9d687e1d4325..3bfd9da58473 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1469,7 +1469,7 @@ static int ata_eh_read_log_10h(struct ata_device *dev,
 	tf->hob_lbah = buf[10];
 	tf->nsect = buf[12];
 	tf->hob_nsect = buf[13];
-	if (ata_id_has_ncq_autosense(dev->id))
+	if (dev->class == ATA_DEV_ZAC && ata_id_has_ncq_autosense(dev->id))
 		tf->auxiliary = buf[14] << 16 | buf[15] << 8 | buf[16];
 
 	return 0;
@@ -1716,7 +1716,8 @@ void ata_eh_analyze_ncq_error(struct ata_link *link)
 	memcpy(&qc->result_tf, &tf, sizeof(tf));
 	qc->result_tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
 	qc->err_mask |= AC_ERR_DEV | AC_ERR_NCQ;
-	if ((qc->result_tf.command & ATA_SENSE) || qc->result_tf.auxiliary) {
+	if (dev->class == ATA_DEV_ZAC &&
+	    ((qc->result_tf.command & ATA_SENSE) || qc->result_tf.auxiliary)) {
 		char sense_key, asc, ascq;
 
 		sense_key = (qc->result_tf.auxiliary >> 16) & 0xff;
@@ -1770,10 +1771,11 @@ static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
 	}
 
 	switch (qc->dev->class) {
-	case ATA_DEV_ATA:
 	case ATA_DEV_ZAC:
 		if (stat & ATA_SENSE)
 			ata_eh_request_sense(qc, qc->scsicmd);
+		/* fall through */
+	case ATA_DEV_ATA:
 		if (err & ATA_ICRC)
 			qc->err_mask |= AC_ERR_ATA_BUS;
 		if (err & (ATA_UNC | ATA_AMNF))
