On 10/4/23 15:43, Petr Tesařík wrote:
> On Wed, 4 Oct 2023 10:25:47 +0900
> Damien Le Moal <dlemoal@xxxxxxxxxx> wrote:
>
>> On 10/4/23 05:07, Petr Tesařík wrote:
>>> I just want to confirm that my understanding of the issue is correct
>>> now. After applying the patch below, my laptop has just survived half a
>>> dozen suspend/resume cycles with autosuspend enabled for the SATA SSD
>>> disk. Without the patch, it usually freezes on first attempt.
>>>
>>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>>> index a371b497035e..87000f89319e 100644
>>> --- a/drivers/ata/libata-scsi.c
>>> +++ b/drivers/ata/libata-scsi.c
>>> @@ -4768,6 +4768,14 @@ void ata_scsi_dev_rescan(struct work_struct *work)
>>> ata_for_each_dev(dev, link, ENABLED) {
>>> struct scsi_device *sdev = dev->sdev;
>>>
>>> + /*
>>> + * If the queue accepts only PM, bail out.
>>> + */
>>> + if (blk_queue_pm_only(sdev->request_queue)) {
>>> + ret = -EAGAIN;
>>> + goto unlock;
>>> + }
>>> +
>>> /*
>>> * If the port was suspended before this was scheduled,
>>> * bail out.
>>
>> This seems sensible to me: scsi_rescan_device() only checks that the device is
>> running, without checking that the device queue is also resumed. So the right
>> place for this check is scsi_rescan_device():
>>
>> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
>> index 3db4d31a03a1..b05a55f498a2 100644
>> --- a/drivers/scsi/scsi_scan.c
>> +++ b/drivers/scsi/scsi_scan.c
>> @@ -1627,12 +1627,13 @@ int scsi_rescan_device(struct scsi_device *sdev)
>> device_lock(dev);
>>
>> /*
>> - * Bail out if the device is not running. Otherwise, the rescan may
>> - * block waiting for commands to be executed, with us holding the
>> - * device lock. This can result in a potential deadlock in the power
>> - * management core code when system resume is on-going.
>> + * Bail out if the device or its queue are not running. Otherwise,
>> + * the rescan may block waiting for commands to be executed, with us
>> + * holding the device lock. This can result in a potential deadlock
>> + * in the power management core code when system resume is on-going.
>> */
>> - if (sdev->sdev_state != SDEV_RUNNING) {
>> + if (sdev->sdev_state != SDEV_RUNNING ||
>> + blk_queue_pm_only(sdev->request_queue)) {
>> ret = -EWOULDBLOCK;
>> goto unlock;
>> }
>>
>> Can you try the above to confirm it works for you ? It should, as that is
>> essentially the same as you did.
>
> After revertung my patch and applying yours, my system can still resume
> from S3. Congrats!
>
> Tested-by: Petr Tesarik <petr@xxxxxxxxxxx>
Thanks. I will send a proper patch asap.
>
> Petr T
--
Damien Le Moal
Western Digital Research
