Re: [PATCH 5/6] nfit, address-range-scrub: rework and simplify ARS state machine

[Dan Williams <dan.j.williams@intel.com>]

On Wed, Apr 4, 2018 at 9:26 AM, Kani, Toshi <toshi.kani@hpe.com> wrote:
> On Mon, 2018-04-02 at 21:46 -0700, Dan Williams wrote:
>  :
>> +static int init_ars(struct acpi_nfit_desc *acpi_desc, struct nfit_spa *nfit_spa,
>> +int query_rc)
>>  {
>> -struct acpi_nfit_system_address *spa = nfit_spa->spa;
>> -unsigned int overflow_retry = scrub_overflow_abort;
>> -u64 init_ars_start = 0, init_ars_len = 0;
>> -struct device *dev = acpi_desc->dev;
>> -unsigned int tmo = scrub_timeout;
>>  int rc;
>>
>> -if (!test_bit(ARS_REQ, &nfit_spa->ars_state) || !nfit_spa->nd_region)
>> -return;
>> +switch (query_rc) {
>> +case 0:
>> +/* ARS is idle, lets look for critical known errors... */
>> +break;
>> +case -EBUSY:
>> +/*
>> + * ARS is already running, some agent thought it was ok
>> + * to busy ARS before handing off to the nfit driver.
>> + */
>> +clear_bit(ARS_SHORT, &nfit_spa->ars_state);
>> +rc = query_rc;
>> +goto out;
>> +case -ENOSPC:
>> +/* ARS continuation needed... */
>> +clear_bit(ARS_SHORT, &nfit_spa->ars_state);
>> +rc = query_rc;
>> +goto out;
>> +default:
>> +rc = query_rc;
>> +goto out;
>> +}
>>
>> +WARN_ON_ONCE(!test_bit(ARS_SHORT, &nfit_spa->ars_state));
>
> I am hitting this WARN_ON_ONCE.  I think there is an issue in the code
> flow that ars_complete() clears ARS_SHORT before init_ars().
>
>   acpi_nfit_scrub
>     acpi_nfit_query_poison
>       ars_status_process_records
>          ars_complete
>     init_ars

Yes, I think we are inadvertently double completing operations. I have
a new version that adds an ARS_DONE flag to make sure we are only
completing ARS once.
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