linux-stable.git/include/linux/libata.h, branch v7.2-rc6

scsi: libsas: terminate deferred commands on time out

2026-07-29T01:52:04+00:00

If a command times out while we have deferred non-NCQ commands waiting to
be issued, the SCSI EH task is not immediately woken up as the waiting
deferred commands are never issued nor completed, thus leaving the SCSI
host in a busy state (shost->host_failed != scsi_host_busy(shost)) which
prevents the SCSI EH task from being woken up. Eventually, when the
deferred commands also time out, the SCSI EH task is woken up and the
timeout processing occurs.

Avoid this unnecessary additional SCSI EH wake up time with the same
method as implemented in libata-scsi, using the eh_timed_out SCSI host
template operation. The function sas_eh_timed_out() implements this
operation and executes the function ata_scsi_retry_deferred_qc()
for SATA devices.

Co-developed-by: Igor Pylypiv 
Signed-off-by: Igor Pylypiv 
Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal 
Reviewed-by: John Garry 
Reviewed-by: Hannes Reinecke 
Tested-by: Igor Pylypiv 
Reviewed-by: Niklas Cassel 
Reviewed-by: Martin K. Petersen

ata: libata-scsi: terminate deferred commands on time out

2026-07-29T01:51:57+00:00

If a command times out while we have deferred non-NCQ commands waiting to
be issued, the SCSI EH task is not immediately woken up as the waiting
deferred commands are never issued nor completed, thus leaving the SCSI
host in a busy state (shost->host_failed != scsi_host_busy(shost)) which
prevents the SCSI EH task from being woken up. Eventually, when the
deferred commands also time out, the SCSI EH task is woken up and the
timeout processing occurs.

Avoid this unnecessary SCSI EH task wake-up additional time by scheduling
a retry of all waiting deferred QCs, using the eh_timed_out SCSI host
template operation. The function ata_scsi_eh_timed_out() is introduced to
implement this operation.

However, terminating deferred commands with DID_REQUEUE to force a retry
by calling the function ata_scsi_requeue_deferred_qc() may still keep the
SCSI host in a busy state because the block layer may immediately re-issue
these commands. The solution to this is to schedule libata EH for the
port which suffered the command timeout to prevent accepting any new
command. ata_scsi_requeue_deferred_qc() is modified to add a call to
ata_port_schedule_eh() for this purpose.

In addition to this change, ata_scsi_requeue_deferred_qc() is also
modified to take a new timedout_scmd scsi command argument which indicates
the SCSI command that timed out. With this additional argument,
ata_scsi_requeue_deferred_qc() can now also terminate with DID_TIME_OUT
any timed out deferred qc, which simplifies ata_scsi_cmd_error_handler().
In this case, ata_scsi_requeue_deferred_qc() returns SCSI_EH_DONE, with
this return value propagated back to the ata_scsi_eh_timed_out() operation
to indicate to scsi_timeout() that the timed out command was handled and
no further processing is needed.

For non-timed out deferred qc that need to be retried,
ata_scsi_requeue_deferred_qc() returns SCSI_EH_NOT_HANDLED, thus
indicating to scsi_timeout() that the timed out command needs to go
through the SCSI EH (and libata EH) processing by adding it to the EH work
queue with scsi_eh_scmd_add().

One side effect of these changes is that the function atapi_qc_complete()
needs to be modified to ensure that a deferred ATAPI command that needs
to be retried is completed with DID_REQUEUE instead of the default
SAM_STAT_GOOD status, and a command that timed out is completed with
DID_TIME_OUT instead of SAM_STAT_CHECK_CONDITION.

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal 
Reviewed-by: Igor Pylypiv 
Tested-by: Igor Pylypiv 
Reviewed-by: Niklas Cassel 
Reviewed-by: Martin K. Petersen

ata: libata-eh: Increase STANDBY IMMEDIATE timeout

2026-07-28T03:04:17+00:00

Correct a previous change (see Fixes) which reduced the standby timeout
from 30 to 5 seconds. Increase it to 15 seconds.

I was troubleshooting an error spotted during system suspend:

    [ 1217.152867] ata1.00: Entering standby power mode
    [ 1222.322948] ata1.00: qc timeout after 5000 msecs (cmd 0xe0)
    [ 1222.324010] ata1.00: STANDBY IMMEDIATE failed (err_mask=0x4)

This drive is a Samsung 870 EVO SSD in good SMART standing, and I wasn't
aware of any reason it should be taking so long to standby. The issue is
intermittent, but I observed it sometimes taking 7 seconds to manually
standby. I assume this was interruption of background maintenance after
a power outage.

As a desktop user, I would prefer to wait the extra 2 seconds at suspend
to let the drive finish its business rather than drop the rails from
under it.

The change from 30 to 5 seconds was implicit when switching suspend
from START STOP UNIT to an internal command with no timeout table entry.
No reason was stated for the change.

Fixes: aa3998dbeb3a ("ata: libata-scsi: Disable scsi device manage_system_start_stop")
Cc: stable@vger.kernel.org
Signed-off-by: Matt Vollrath 
Assisted-by: Claude:claude-5-fable
Signed-off-by: Damien Le Moal

ata: Annotate functions in the issuing path with __must_hold()

2026-06-01T17:14:41+00:00

Annotate the following functions used in the issuing path:
ata_qc_issue(), ata_sas_queuecmd(), ata_scsi_qc_issue(),
ata_scsi_translate(), __ata_scsi_queuecmd()

These functions are all used in the issuing path, so context analysis will
be able to verify that the ap lock is held, from it is taken in
sas_queuecommand() or ata_scsi_queuecmd() all the way down to
ata_qc_issue().

Commenting out the spin_lock_irqsave() successfully results in a compiler
error on Clang 23.

Signed-off-by: Bart Van Assche 
Co-developed-by: Niklas Cassel 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Niklas Cassel

ata: libata: Document when host->eh_mutex should be held

2026-06-01T17:09:08+00:00

Annotate the following functions with __must_hold(&host->eh_mutex):
 * All ata_port_operations.error_handler() implementations.
 * ata_eh_reset() and ata_eh_recover() because these functions call
   ata_eh_release() and ata_eh_acquire().
 * All callers of ata_eh_reset() and ata_eh_recover().

Enable Clang's context analysis. This will cause the build to fail if
e.g. a locking bug would be introduced in an error path. This patch
should not affect the generated assembler code.

Signed-off-by: Bart Van Assche 
[cassel: drop note about clang 23 from commit log]
Signed-off-by: Niklas Cassel

ata: libata-scsi: do not needlessly defer commands when using PMP with FBS

2026-05-18T10:26:51+00:00

The ACS specification does not allow a non-NCQ command to be issued while
an NCQ command is outstanding.

Commit 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
introduced a feature where a deferred non-NCQ command gets issued from a
workqueue. The design stores a single non-NCQ command per port.

However, when using Port Multipliers (PMPs), specifically PMPs that
support FIS-Based Switching (FBS), non-NCQ and NCQ commands can be mixed
on the same port, just not for the same link, see e.g. ata_std_qc_defer()
which is, and always has operated on a per-link basis.

Therefore, move the deferred_qc from struct ata_port to struct ata_link.
This way, when using a PMP with FBS, we will not needlessly defer commands
to all other links, just because one link issued a non-NCQ command while
having an NCQ command outstanding. Only commands for that specific link
will be deferred. This is in line with how PMPs with FBS worked before
commit 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation").

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Tested-by: Tommy Kelly 
Reviewed-by: Damien Le Moal 
Signed-off-by: Niklas Cassel

ata: libata-scsi: do not use the deferred QC feature on PMPs with CBS

2026-05-18T10:25:28+00:00

When using Port Multipliers (PMPs) with Command-Based Switching (CBS), you
can only issue commands to one link at a time. For PMPs with CBS, there is
already code to handle commands being sent to different links in
sata_pmp_qc_defer_cmd_switch() using ap->excl_link. sata_sil24 also makes
use of ap->excl_link.

A user on the list reported that commit 0ea84089dbf6 ("ata: libata-scsi:
avoid Non-NCQ command starvation") broke PMPs with CBS. The commit
introduced code that stores a deferred qc in ap->deferred_qc, to later be
issued via a workqueue. It turns out that this change is incompatible with
the existing ap->excl_link handling used by PMPs with CBS.

Thus, modify sata_pmp_qc_defer_cmd_switch() and sil24_qc_defer() to return
ATA_DEFER_LINK_EXCL, and make sure that the deferred QC handling via
workqueue is not used for this return value.

This way, PMPs with CBS will work once again. Note that the starvation
referenced in commit 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ
command starvation") can only happen on libsas ports, and libsas does not
support Port Multipliers, thus there is no harm of reverting back to the
previous way of deferring commands for PMPs with CBS.

Non-libsas ports connected to anything but a PMP with CBS (e.g. a normal
drive or a PMP with FBS) will continue using the deferred workqueue, since
it does result in lower completion latencies for non-NCQ commands, even
though the workqueue is not strictly needed to avoid starvation for
non-libsas ports.

If we want to modify the scope of the workqueue issuing to also handle
PMPs with CBS, then we should ensure that we can save both NCQ and non-NCQ
commands in ap->deferred_qc, while also removing the existing PMP CBS
handling using ap->excl_link, such that we don't duplicate features.

While at it, also add a comment explaining how the ap->excl_link mechanism
works.

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Tested-by: Tommy Kelly 
Reported-by: Tommy Kelly 
Closes: https://lore.kernel.org/linux-ide/ce09cc21-a8e9-4845-b205-35411e22fba9@tkel.ly/
Reviewed-by: Damien Le Moal 
Signed-off-by: Niklas Cassel

ata: libata-eh: avoid unnecessary calls to ata_scsi_port_error_handler()

2026-02-25T06:20:18+00:00

When handling SCSI command timeouts, if we had no actual command
timeouts (either because the command was a deferred qc or the completion
path won the race with ata_scsi_cmd_error_handler()), we do not need to
go through a port error handling, as there was in fact no errors at all.

Modify ata_scsi_cmd_error_handler() to return the number of commands
that timed out and use this return value in ata_scsi_error() to call
ata_scsi_port_error_handler() only if we had command timeouts, or if
the port EH has already been scheduled due to failed commands.
Otherwise, simply call scsi_eh_flush_done_q() to finish the completed
commands without running the full port error handling.

Signed-off-by: Damien Le Moal 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Niklas Cassel 
Signed-off-by: Niklas Cassel

ata: libata-scsi: make ata_scsi_simulate() static

2026-02-24T00:40:58+00:00

ata_scsi_simulate() is called only from libata-scsi.c. Move this
function definition as a static function before its call in
__ata_scsi_queuecmd() and remove its declaration from
include/linux/libata.h.

No functional changes.

Signed-off-by: Damien Le Moal 
Reviewed-by: Hannes Reinecke

Merge tag 'ata-6.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/libata/linux

2026-02-13T01:12:43+00:00

Pull ATA updates from Damien Le Moal:

 - Cleanup IRQ masking in the handling of completed report zones
   commands (Niklas)

 - Improve the handling of Thunderbolt attached devices to speed up
   device removal (Henry)

 - Several patches to generalize the existing max_sec quirks to
   facilitates quirking the maximum command size of buggy drives, many
   of which have recently showed up with the recent increase of the
   default max_sectors block limit (Niklas)

 - Cleanup the ahci-platform and sata dt-bindings schema (Rob,
   Manivannan)

 - Improve device node scan in the ahci-dwc driver (Krzysztof)

 - Remove clang W=1 warnings with the ahci-imx and ahci-xgene drivers
   (Krzysztof)

 - Fix a long standing potential command starvation situation with
   non-NCQ commands issued when NCQ commands are on-going (me)

 - Limit max_sectors to 8191 on the INTEL SSDSC2KG480G8 SSD (Niklas)

 - Remove Vesa Local Bus (VLB) support in the pata_legacy driver (Ethan)

 - Simple fixes in the pata_cypress (typo) and pata_ftide010 (timing)
   drivers (Ethan, Linus W)

* tag 'ata-6.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/libata/linux:
  ata: pata_ftide010: Fix some DMA timings
  ata: pata_cypress: fix typo in error message
  ata: pata_legacy: remove VLB support
  ata: libata-core: Quirk INTEL SSDSC2KG480G8 max_sectors
  dt-bindings: ata: sata: Document the graph port
  ata: libata-scsi: avoid Non-NCQ command starvation
  ata: libata-scsi: refactor ata_scsi_translate()
  ata: ahci-xgene: Fix Wvoid-pointer-to-enum-cast warning
  ata: ahci-imx: Fix Wvoid-pointer-to-enum-cast warning
  ata: ahci-dwc: Simplify with scoped for each OF child loop
  dt-bindings: ata: ahci-platform: Drop unnecessary select schema
  ata: libata: Allow more quirks
  ata: libata: Add libata.force parameter max_sec
  ata: libata: Add support to parse equal sign in libata.force
  ata: libata: Change libata.force to use the generic ATA_QUIRK_MAX_SEC quirk
  ata: libata: Add ata_force_get_fe_for_dev() helper
  ata: libata: Add ATA_QUIRK_MAX_SEC and convert all device quirks
  ata: libata: avoid long timeouts on hot-unplugged SATA DAS
  ata: libata-scsi: Remove superfluous local_irq_save()