[PATCH v=2] ata: libata-scsi: fix requeue of deferred ATA PASS-THROUGH commands

[PATCH v=2] ata: libata-scsi: fix requeue of deferred ATA PASS-THROUGH commands

[Igor Pylypiv]

Commit 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
introduced ata_scsi_requeue_deferred_qc() to handle commands deferred
during resets or NCQ failures. This deferral logic completed commands
with DID_SOFT_ERROR to trigger a retry in the SCSI mid-layer.

However, DID_SOFT_ERROR is subject to scsi_cmd_retry_allowed() checks.
ATA PASS-THROUGH commands sent via SG_IO ioctl have scmd->allowed set
to zero. This causes the mid-layer to fail the command immediately
instead of retrying, even though the command was never actually issued
to the hardware.

Switch to DID_REQUEUE to ensure these commands are inserted back into
the request queue regardless of retry limits.

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
---

Changes from v1:
- Dropped the usage of set_host_byte() because it is logically a separate
  change from what this commit is fixing. set_host_byte() does not clear
  the status byte and the ML byte.

 drivers/ata/libata-scsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 3b65df914ebb..cd607911d724 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1692,7 +1692,7 @@ void ata_scsi_requeue_deferred_qc(struct ata_port *ap)
 	/*
 	 * If we have a deferred qc when a reset occurs or NCQ commands fail,
 	 * do not try to be smart about what to do with this deferred command
-	 * and simply retry it by completing it with DID_SOFT_ERROR.
+	 * and simply requeue it by completing it with DID_REQUEUE.
 	 */
 	if (!qc)
 		return;
@@ -1701,7 +1701,7 @@ void ata_scsi_requeue_deferred_qc(struct ata_port *ap)
 	ap->deferred_qc = NULL;
 	cancel_work(&ap->deferred_qc_work);
 	ata_qc_free(qc);
-	scmd->result = (DID_SOFT_ERROR << 16);
+	scmd->result = (DID_REQUEUE << 16);
 	scsi_done(scmd);
 }
 
-- 
2.53.0.1213.gd9a14994de-goog

Re: [PATCH v=2] ata: libata-scsi: fix requeue of deferred ATA PASS-THROUGH commands

[Sergey Shtylyov]

On 4/12/26 6:36 PM, Igor Pylypiv wrote:

> Commit 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
> introduced ata_scsi_requeue_deferred_qc() to handle commands deferred
> during resets or NCQ failures. This deferral logic completed commands
> with DID_SOFT_ERROR to trigger a retry in the SCSI mid-layer.
> 
> However, DID_SOFT_ERROR is subject to scsi_cmd_retry_allowed() checks.
> ATA PASS-THROUGH commands sent via SG_IO ioctl have scmd->allowed set
> to zero. This causes the mid-layer to fail the command immediately
> instead of retrying, even though the command was never actually issued
> to the hardware.
> 
> Switch to DID_REQUEUE to ensure these commands are inserted back into
> the request queue regardless of retry limits.
> 
> Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
> Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
> Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
> ---
> 
> Changes from v1:
> - Dropped the usage of set_host_byte() because it is logically a separate
>   change from what this commit is fixing. set_host_byte() does not clear
>   the status byte and the ML byte.
> 
>  drivers/ata/libata-scsi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 3b65df914ebb..cd607911d724 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
[...]
> @@ -1701,7 +1701,7 @@ void ata_scsi_requeue_deferred_qc(struct ata_port *ap)
>  	ap->deferred_qc = NULL;
>  	cancel_work(&ap->deferred_qc_work);
>  	ata_qc_free(qc);
> -	scmd->result = (DID_SOFT_ERROR << 16);
> +	scmd->result = (DID_REQUEUE << 16);

   You could drop the useless parens, while at it...

>  	scsi_done(scmd);
>  }
>  

MBR, Sergey

Re: [PATCH v=2] ata: libata-scsi: fix requeue of deferred ATA PASS-THROUGH commands

[Niklas Cassel]

On Sun, 12 Apr 2026 08:36:37 -0700, Igor Pylypiv wrote:
> Commit 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
> introduced ata_scsi_requeue_deferred_qc() to handle commands deferred
> during resets or NCQ failures. This deferral logic completed commands
> with DID_SOFT_ERROR to trigger a retry in the SCSI mid-layer.
> 
> However, DID_SOFT_ERROR is subject to scsi_cmd_retry_allowed() checks.
> ATA PASS-THROUGH commands sent via SG_IO ioctl have scmd->allowed set
> to zero. This causes the mid-layer to fail the command immediately
> instead of retrying, even though the command was never actually issued
> to the hardware.
> 
> [...]

Hello Igor,

Considering that Linus is expected for release 7.0 any minute now (it is
already Sunday afternoon), it seems too late to send this as a PR for 7.0.

The fix will have to be backported to v7.0 stable instead.

Therefore, I rebased your patch on libata/for-next
(without any parens - the comment from Sergey).


Applied to libata/linux.git (for-7.1), thanks!

[1/1] ata: libata-scsi: fix requeue of deferred ATA PASS-THROUGH commands
      https://git.kernel.org/libata/linux/c/8ebf408e

Kind regards,
Niklas