Re: [Intel-gfx] [PATCH 4/4] drm/i915/selftest: Always cancel semaphore on error

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On 3/14/22 19:20, Ramalingam C wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
>
> Ensure that we always signal the semaphore when timing out, so that if it
> happens to be stuck waiting for the semaphore we will quickly recover
> without having to wait for a reset.
>
> Reported-by: CQ Tang <cq.tang@intel.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: CQ Tang <cq.tang@intel.com>
> cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>


> ---
>   drivers/gpu/drm/i915/gt/selftest_lrc.c | 17 ++++++++---------
>   1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> index b9cc89de01bf..ae16668dd9d4 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> @@ -1435,18 +1435,17 @@ static int __lrc_isolation(struct intel_engine_cs *engine, u32 poison)
>   	}
>   
>   	err = poison_registers(B, poison, sema);
> -	if (err) {
> -		WRITE_ONCE(*sema, -1);
> -		i915_request_put(rq);
> -		goto err_result1;
> -	}
> -
> -	if (i915_request_wait(rq, 0, HZ / 2) < 0) {
> -		i915_request_put(rq);
> +	if (err == 0 && i915_request_wait(rq, 0, HZ / 2) < 0) {
> +		pr_err("%s(%s): wait for results timed out\n",
> +		       __func__, engine->name);
>   		err = -ETIME;
> -		goto err_result1;
>   	}
> +
> +	/* Always cancel the semaphore wait, just in case the GPU gets stuck */
> +	WRITE_ONCE(*sema, -1);
>   	i915_request_put(rq);
> +	if (err)
> +		goto err_result1;
>   
>   	err = compare_isolation(engine, ref, result, A, poison);
>