kernel/git/stable/linux.git/drivers/ata/libata-eh.c, branch linux-7.2.y

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: 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: Add an argument to ata_eh_reset()

2026-06-01T17:09:07+00:00

Pass the ATA port pointer as first argument to ata_eh_reset(). No functionality has been changed. This patch prepares for enabling lock context analysis. Without this patch, lockdep_assert_held() statements would have to be added before each ata_eh_reset() call because the compiler doesn't know that ap->link.p == ap. See also ata_link_init(). Signed-off-by: Bart Van Assche Signed-off-by: Niklas Cassel

ata: libata-eh: queue hotplug work on the system_dfl_long_wq workqueue

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

ata_scsi_port_error_handler() uses schedule_delayed_work() to queue the ap->hotplug_task work. schedule_delayed_work() always uses the system_percpu_wq per-cpu workqueue. ata_scsi_scan_host() queues the ap->hotplug_task work on the unbound system_dfl_long_wq workqueue. It seems counter-intuitive to queue the same work on two different workqueues. Thus, change ata_scsi_port_error_handler() to also queue the ap->hotplug_task work on the system_dfl_long_wq workqueue, such that the work is always queued on the same workqueue. Reviewed-by: Damien Le Moal 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-eh: Do not retry reset if the device is gone

2026-04-02T18:18:29+00:00

If a device is hot-unplugged or otherwise disappears during error handling, ata_eh_reset() may fail with -ENODEV. Currently, the error handler will continue to retry the reset operation up to max_tries times. Prevent unnecessary reset retries by exiting the loop early when ata_do_reset() returns -ENODEV. Reviewed-by: Damien Le Moal Signed-off-by: Igor Pylypiv Signed-off-by: Niklas Cassel

Merge branch 'for-7.0-fixes' into for-7.1

2026-03-20T10:13:32+00:00

ata: libata-eh: Fix detection of deferred qc timeouts

2026-03-06T08:58:47+00:00

If the ata_qc_for_each_raw() loop finishes without finding a matching SCSI command for any QC, the variable qc will hold a pointer to the last element examined, which has the tag i == ATA_MAX_QUEUE - 1. This qc can match the port deferred QC (ap->deferred_qc). If that happens, the condition qc == ap->deferred_qc evaluates to true despite the loop not breaking with a match on the SCSI command for this QC. In that case, the error handler mistakenly intercepts a command that has not been issued yet and that has not timed out, and thus erroneously returning a timeout error. Fix the problem by checking for i < ATA_MAX_QUEUE in addition to qc == ap->deferred_qc. The problem was found by an experimental code review agent based on gemini-3.1-pro while reviewing backports into v6.18.y. Assisted-by: Gemini:gemini-3.1-pro Fixes: eddb98ad9364 ("ata: libata-eh: correctly handle deferred qc timeouts") Signed-off-by: Guenter Roeck [cassel: modified commit log as suggested by Damien] Reviewed-by: Damien Le Moal Signed-off-by: Niklas Cassel

ata: libata: cancel pending work after clearing deferred_qc

2026-03-04T09:42:12+00:00

Syzbot reported a WARN_ON() in ata_scsi_deferred_qc_work(), caused by ap->ops->qc_defer() returning non-zero before issuing the deferred qc. ata_scsi_schedule_deferred_qc() is called during each command completion. This function will check if there is a deferred QC, and if ap->ops->qc_defer() returns zero, meaning that it is possible to queue the deferred qc at this time (without being deferred), then it will queue the work which will issue the deferred qc. Once the work get to run, which can potentially be a very long time after the work was scheduled, there is a WARN_ON() if ap->ops->qc_defer() returns non-zero. While we hold the ap->lock both when assigning and clearing deferred_qc, and the work itself holds the ap->lock, the code currently does not cancel the work after clearing the deferred qc. This means that the following scenario can happen: 1) One or several NCQ commands are queued. 2) A non-NCQ command is queued, gets stored in ap->deferred_qc. 3) Last NCQ command gets completed, work is queued to issue the deferred qc. 4) Timeout or error happens, ap->deferred_qc is cleared. The queued work is currently NOT canceled. 5) Port is reset. 6) One or several NCQ commands are queued. 7) A non-NCQ command is queued, gets stored in ap->deferred_qc. 8) Work is finally run. Yet at this time, there is still NCQ commands in flight. The work in 8) really belongs to the non-NCQ command in 2), not to the non-NCQ command in 7). The reason why the work is executed when it is not supposed to, is because it was never canceled when ap->deferred_qc was cleared in 4). Thus, ensure that we always cancel the work after clearing ap->deferred_qc. Another potential fix would have been to let ata_scsi_deferred_qc_work() do nothing if ap->ops->qc_defer() returns non-zero. However, canceling the work when clearing ap->deferred_qc seems slightly more logical, as we hold the ap->lock when clearing ap->deferred_qc, so we know that the work cannot be holding the lock. (The function could be waiting for the lock, but that is okay since it will do nothing if ap->deferred_qc is not set.) Reported-by: syzbot+bcaf842a1e8ead8dfb89@syzkaller.appspotmail.com Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation") Fixes: eddb98ad9364 ("ata: libata-eh: correctly handle deferred qc timeouts") Reviewed-by: Igor Pylypiv Reviewed-by: Damien Le Moal Signed-off-by: Niklas Cassel