Re: [Intel-gfx] [PATCH] drm/i915/selftests: Use clear_and_wake_up_bit() for the per-engine reset bitlocks

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Nov 04, 2021 at 01:58:44PM +0100, Thomas Hellström wrote:
> Some selftests assume that nothing will attempt to grab these bitlocks
> while they are held by the selftests. With GuC, for example, that is
> not true because the hanging workloads may cause the GuC code to attempt
> to grab them for a global reset, and that may cause it to end up
> sleeping on the bit never waking up. Regardless whether that will be
> the final solution for GuC, use clear_and_wake_up_bit() pending a more
> thorough investigation on how this should be handled moving forward.
> 
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

This series will also fix the CI crash:
https://patchwork.freedesktop.org/series/96406/

Regardless of the above series this one looks correct and needed.

With that:
Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/i915/gt/selftest_hangcheck.c | 8 ++++----
>  drivers/gpu/drm/i915/selftests/igt_reset.c   | 2 +-
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
> index 7e2d99dd012d..8590419be4c6 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
> @@ -528,7 +528,7 @@ static int igt_reset_nop_engine(void *arg)
>  				break;
>  			}
>  		} while (time_before(jiffies, end_time));
> -		clear_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
> +		clear_and_wake_up_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
>  		st_engine_heartbeat_enable(engine);
>  
>  		pr_info("%s(%s): %d resets\n", __func__, engine->name, count);
> @@ -679,7 +679,7 @@ static int igt_reset_fail_engine(void *arg)
>  out:
>  		pr_info("%s(%s): %d resets\n", __func__, engine->name, count);
>  skip:
> -		clear_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
> +		clear_and_wake_up_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
>  		st_engine_heartbeat_enable(engine);
>  		intel_context_put(ce);
>  
> @@ -824,7 +824,7 @@ static int __igt_reset_engine(struct intel_gt *gt, bool active)
>  			if (err)
>  				break;
>  		} while (time_before(jiffies, end_time));
> -		clear_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
> +		clear_and_wake_up_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
>  		st_engine_heartbeat_enable(engine);
>  		pr_info("%s: Completed %lu %s resets\n",
>  			engine->name, count, active ? "active" : "idle");
> @@ -1165,7 +1165,7 @@ static int __igt_reset_engines(struct intel_gt *gt,
>  			if (err)
>  				break;
>  		} while (time_before(jiffies, end_time));
> -		clear_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
> +		clear_and_wake_up_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
>  		st_engine_heartbeat_enable_no_pm(engine);
>  
>  		pr_info("i915_reset_engine(%s:%s): %lu resets\n",
> diff --git a/drivers/gpu/drm/i915/selftests/igt_reset.c b/drivers/gpu/drm/i915/selftests/igt_reset.c
> index 9f8590b868a9..a2838c65f8a5 100644
> --- a/drivers/gpu/drm/i915/selftests/igt_reset.c
> +++ b/drivers/gpu/drm/i915/selftests/igt_reset.c
> @@ -36,7 +36,7 @@ void igt_global_reset_unlock(struct intel_gt *gt)
>  	enum intel_engine_id id;
>  
>  	for_each_engine(engine, gt, id)
> -		clear_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
> +		clear_and_wake_up_bit(I915_RESET_ENGINE + id, &gt->reset.flags);
>  
>  	clear_bit(I915_RESET_BACKOFF, &gt->reset.flags);
>  	wake_up_all(&gt->reset.queue);
> -- 
> 2.31.1
>