[Intel-gfx] [PATCH] drm/i915/selftests: Fix mutex imbalance for igt_render_engine_reset_fallback

[Michel Thierry]

On 23/06/17 06:19, Chris Wilson wrote:
> Smatch spots:
>
> drivers/gpu/drm/i915/selftests/intel_hangcheck.c:669 igt_render_engine_reset_fallback() error: double unlock 'mutex:&i915->drm.struct_mutex'
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by: Michel Thierry <michel.thierry at intel.com>

> ---
>  drivers/gpu/drm/i915/selftests/intel_hangcheck.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> index af475189bd52..7096c3911cd3 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> @@ -597,12 +597,12 @@ static int igt_render_engine_reset_fallback(void *arg)
>
>         err = hang_init(&h, i915);
>         if (err)
> -               goto unlock;
> +               goto err_unlock;
>
>         rq = hang_create_request(&h, engine, i915->kernel_context);
>         if (IS_ERR(rq)) {
>                 err = PTR_ERR(rq);
> -               goto fini;
> +               goto err_fini;
>         }
>
>         i915_gem_request_get(rq);
> @@ -614,7 +614,7 @@ static int igt_render_engine_reset_fallback(void *arg)
>         if (!wait_for_hang(&h, rq)) {
>                 pr_err("Failed to start request %x\n", rq->fence.seqno);
>                 err = -EIO;
> -               goto out_rq;
> +               goto err_request;
>         }
>
>         reset_engine_count = i915_reset_engine_count(&i915->gpu_error, engine);
> @@ -646,13 +646,14 @@ static int igt_render_engine_reset_fallback(void *arg)
>          */
>         if (i915_terminally_wedged(&i915->gpu_error)) {
>                 set_bit(I915_RESET_BACKOFF, &i915->gpu_error.flags);
> -               mutex_lock(&i915->drm.struct_mutex);
>                 rq->fence.error = 0;
>
> +               mutex_lock(&i915->drm.struct_mutex);
>                 set_bit(I915_RESET_HANDOFF, &i915->gpu_error.flags);
>                 i915_reset(i915);
>                 GEM_BUG_ON(test_bit(I915_RESET_HANDOFF,
>                                     &i915->gpu_error.flags));
> +               mutex_unlock(&i915->drm.struct_mutex);
>
>                 if (i915_reset_count(&i915->gpu_error) == reset_count) {
>                         pr_err("No full GPU reset recorded!\n");
> @@ -663,10 +664,8 @@ static int igt_render_engine_reset_fallback(void *arg)
>
>  out_rq:
>         i915_gem_request_put(rq);
> -fini:
>         hang_fini(&h);
> -unlock:
> -       mutex_unlock(&i915->drm.struct_mutex);
> +out_backoff:
>         clear_bit(I915_RESET_BACKOFF, &i915->gpu_error.flags);
>         wake_up_all(&i915->gpu_error.reset_queue);
>
> @@ -674,6 +673,14 @@ static int igt_render_engine_reset_fallback(void *arg)
>                 return -EIO;
>
>         return err;
> +
> +err_request:
> +       i915_gem_request_put(rq);
> +err_fini:
> +       hang_fini(&h);
> +err_unlock:
> +       mutex_unlock(&i915->drm.struct_mutex);
> +       goto out_backoff;
>  }
>
>  int intel_hangcheck_live_selftests(struct drm_i915_private *i915)
> --
> 2.13.1
>
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