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

["Kani, Toshi" <toshi.kani@hpe.com>]

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

Thanks!
-Toshi
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