kernel/git/stable/linux.git/drivers/ata/libata-scsi.c, branch master

ata: libata-scsi: limit simulated SCSI command copy to response length

2026-07-03T04:44:18+00:00

The function ata_scsi_rbuf_fill() is used to copy the response of emulated SCSI commands from ata_scsi_rbuf to the SCSI command's scatterlist. Currently, sg_copy_from_buffer() is called with the size argument set to ATA_SCSI_RBUF_SIZE (2048 bytes). Since ata_scsi_rbuf is zeroed out before the simulation actor is invoked, copying the full buffer size causes the remainder of the SCSI command's transfer buffer (beyond the actual response length 'len') to be overwritten with zeroes. This clobbers any pre-existing sentinel values or data in the caller's buffer tail, even though the correct residual count is reported via scsi_set_resid(). Fix this by passing the actual response length 'len' as the copy size to sg_copy_from_buffer(), ensuring that the tail of the caller's buffer remains untouched. Also, add a defensive check to ensure that the actor does not return a length exceeding the static buffer capacity. If this occurs, trigger a WARN_ON(), fail the command with an aborted command error, and return immediately without copying any data. The fix was tested by invoking an SCSI SG_IO INQUIRY on an ATA disk on vanilla build, and build with the fix. Confirmed that the input buffer's tail end remains unmodified with the fix. Fixes: 5251ae224d8d ("ata: libata-scsi: Return residual for emulated SCSI commands") Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Karuna Ramkumar Signed-off-by: Damien Le Moal

ata: libata-core: Reject an invalid concurrent positioning ranges count

2026-07-03T04:44:18+00:00

ata_dev_config_cpr() takes the number of range descriptors from buf[0] of the concurrent positioning ranges log (up to 255), which the device reports independently of the log size in the GPL directory. The count is then walked at a fixed 32-byte stride in two places with no bound: the log read here, and the INQUIRY VPD page B9h emitter, which writes one descriptor per range into the fixed 2048-byte ata_scsi_rbuf. A device reporting a count larger than its own log overflows the read buffer (up to 7704 bytes past a 512-byte slab), and a count above 62 overflows the response buffer on the emit side. Bound the count once, on probe, against both the log the device returned and the number of descriptors the VPD B9h response buffer can hold (ATA_DEV_MAX_CPR, derived from the rbuf size). Reject an out-of-range count with a warning; this keeps the emitter in bounds with no separate change there. Suggested-by: Damien Le Moal Fixes: fe22e1c2f705 ("libata: support concurrent positioning ranges log") Fixes: c745dfc541e7 ("libata: fix reading concurrent positioning ranges log") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Niklas Cassel 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: Pass ap parameter directly to functions in the issuing path

2026-06-01T17:14:29+00:00

Context analysis cannot recognize that qc->ap == ap. Therefore, grow a struct ata_port parameter to the following functions: ata_qc_issue(), __ata_scsi_queuecmd(), and ata_scsi_translate() such that we will be able to enable context analysis in a follow-up commit. No functionality has been changed. Signed-off-by: Bart Van Assche Reviewed-by: Hannes Reinecke Signed-off-by: Niklas Cassel

ata: libata-scsi: Move long delayed work on system_dfl_long_wq

2026-06-01T17:07:37+00:00

Currently the code enqueue work items using {queue|mod}_delayed_work(), using system_long_wq. This workqueue should be used when long works are expected, but it is a per-cpu workqueue. This is important because queue_delayed_work() queue the work using: queue_delayed_work_on(WORK_CPU_UNBOUND, ...); Note that WORK_CPU_UNBOUND = NR_CPUS. This would end up calling __queue_delayed_work() that does: if (housekeeping_enabled(HK_TYPE_TIMER)) { // [....] } else { if (likely(cpu == WORK_CPU_UNBOUND)) add_timer_global(timer); else add_timer_on(timer, cpu); } So when cpu == WORK_CPU_UNBOUND the timer is global and is not using a specific CPU. Later, when __queue_work() is called: if (req_cpu == WORK_CPU_UNBOUND) { if (wq->flags & WQ_UNBOUND) cpu = wq_select_unbound_cpu(raw_smp_processor_id()); else cpu = raw_smp_processor_id(); } Because the wq is not unbound, it takes the CPU where the timer fired and enqueue the work on that CPU. The consequence of all of this is that the work can run anywhere, depending on where the timer fired. Recently, a new unbound workqueue specific for long running work has been added: c116737e972e ("workqueue: Add system_dfl_long_wq for long unbound works") So change system_long_wq with system_dfl_long_wq so that the work may benefit from scheduler task placement. Signed-off-by: Marco Crivellari 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-scsi: do not use the deferred QC feature for ATA_DEFER_PORT

2026-05-18T10:11:46+00:00

The deferred QC feature was meant to handle mixed NCQ and non-NCQ commands, i.e. for return value ATA_DEFER_LINK. ATA_DEFER_PORT is returned by PATA drivers, but also certain SATA drivers like sata_mv and sata_sil24 that uses ap->excl_link to workaround hardware bugs in these HBAs. Regardless of the reason, using the deferred QC feature for ATA_DEFER_PORT is always wrong, and will break the ap->excl_link usage of the SATA drivers that rely on that feature. Modify ata_scsi_qc_issue() to only use the deferred QC feature when mixing NCQ and non-NCQ commands, i.e. ATA_DEFER_LINK. 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: improve readability of ata_scsi_qc_issue()

2026-05-18T10:10:34+00:00

Improve readability of ata_scsi_qc_issue(). No functional changes. Tested-by: Tommy Kelly Reviewed-by: Damien Le Moal Signed-off-by: Niklas Cassel

ata: libata-scsi: fix requeue of deferred ATA PASS-THROUGH commands

2026-04-12T17:57:59+00:00

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 Signed-off-by: Igor Pylypiv Signed-off-by: Niklas Cassel