linux-kernel - [PATCH AUTOSEL 4.14 079/105] libata: don't request sense data on !ZAC ATA devices

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Date:   Mon, 15 Jul 2019 10:28:13 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Tejun Heo <tj@...nel.org>, Hannes Reinecke <hare@...e.com>,
        Masato Suzuki <masato.suzuki@....com>,
        Damien Le Moal <damien.lemoal@....com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        linux-ide@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 079/105] libata: don't request sense data on !ZAC ATA devices

From: Tejun Heo <tj@...nel.org>

[ Upstream commit ca156e006add67e4beea7896be395160735e09b0 ]

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.

Reviewed-by: Hannes Reinecke <hare@...e.com>
Tested-by: Masato Suzuki <masato.suzuki@....com>
Reviewed-by: Damien Le Moal <damien.lemoal@....com>
Signed-off-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.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 2651c81d1edf..c398be4b1797 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1535,7 +1535,7 @@ 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;
@@ -1784,7 +1784,8 @@ 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;
@@ -1838,10 +1839,11 @@ 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))
-- 
2.20.1