linux-kernel - [PATCH] ata: libata-scsi: fix bogus SCSI sense after abort

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Message-Id: <20230623181908.2032764-1-lorenz@brun.one>
Date:   Fri, 23 Jun 2023 20:19:07 +0200
From:   Lorenz Brun <lorenz@...n.one>
To:     Damien Le Moal <dlemoal@...nel.org>
Cc:     linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ata: libata-scsi: fix bogus SCSI sense after abort

Since commit 058e55e120ca which fixed that commands without valid
error/status codes did not result in any sense error, the returned sense
errors were completely bogus as ata_to_sense_error did not have valid
inputs in the first place.

For example the following ATA error

exception Emask 0x10 SAct 0x20c000 SErr 0x280100 action 0x6 frozen
irq_stat 0x08000000, interface fatal error
SError: { UnrecovData 10B8B BadCRC }
failed command: READ FPDMA QUEUED
cmd 60/e0:70:20:0a:00/00:00:00:00:00/40 tag 14 ncq dma 114688 in
res 40/00:ac:20:5e:50/00:00:5d:01:00/40 Emask 0x10 (ATA bus error)
status: { DRDY }

got turned into the following nonsensical SCSI error

FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
Sense Key : Illegal Request [current]
Add. Sense: Unaligned write command
CDB: Read(16) 88 00 00 00 00 00 00 00 0a 20 00 00 00 e0 00 00

This has nothing to do with an unaligned write command, but is due to an
ATA EH-triggered abort. But ata_to_sense_error only knows about
status and error, both of which aren't even valid here as the command
has been aborted.

Add an additional section to ata_gen_ata_sense which handles
errors not coming from the device first, before calling into
ata_to_sense_error.

According to the SAT-5 spec a reset should cause a Unit Attention event,
which the SCSI subsystem should handle to retry its commands but I
am not sure how much of that infra is present in Linux's SCSI layer, so
this is a simpler solution.

Signed-off-by: Lorenz Brun <lorenz@...n.one>
---
 drivers/ata/libata-scsi.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 551077cea4e4..61c6a4e8123a 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -13,6 +13,7 @@
  *  - http://www.t13.org/
  */
 
+#include "scsi/scsi_proto.h"
 #include <linux/compat.h>
 #include <linux/slab.h>
 #include <linux/kernel.h>
@@ -1013,6 +1014,21 @@ static void ata_gen_ata_sense(struct ata_queued_cmd *qc)
 		ata_scsi_set_sense(dev, cmd, NOT_READY, 0x04, 0x21);
 		return;
 	}
+	if (qc->err_mask & (AC_ERR_HSM | AC_ERR_ATA_BUS | AC_ERR_HOST_BUS |
+		AC_ERR_SYSTEM | AC_ERR_OTHER)) {
+		/* Command aborted because of some issue with the ATA subsystem
+		 * Should technically cause unit attention, but this is better
+		 * than nothing, which results in nonsensical errors.
+		 * POWER ON, RESET, OR BUS DEVICE RESET OCCURRED
+		 */
+		ata_scsi_set_sense(dev, cmd, ABORTED_COMMAND, 0x29, 0x00);
+		return;
+	}
+	if (qc->err_mask & AC_ERR_TIMEOUT) {
+		/* COMMAND TIMEOUT DURING PROCESSING */
+		ata_scsi_set_sense(dev, cmd, ABORTED_COMMAND, 0x2e, 0x02);
+		return;
+	}
 	/* Use ata_to_sense_error() to map status register bits
 	 * onto sense key, asc & ascq.
 	 */
-- 
2.40.1