linux-kernel - Re: [PATCH v2 6/6] drm/v3d: Invalidate the caches from the outside in.

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Message-ID: <CAApk1dXGx4BQOgRHU1F0yR+1oO6FhLGS-JHdCENMNVJ_qLouQg@mail.gmail.com>
Date:   Tue, 4 Dec 2018 12:01:36 +0000
From:   Dave Emett <david.emett@...adcom.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Thomas Spurden <thomas.spurden@...adcom.com>
Subject: Re: [PATCH v2 6/6] drm/v3d: Invalidate the caches from the outside in.

On Mon, 3 Dec 2018 at 22:24, Eric Anholt <eric@...olt.net> wrote:
>
> This would be a fairly obscure race, but let's make sure we don't ever
> lose it.
>
> Signed-off-by: Eric Anholt <eric@...olt.net>

Reviewed-by: Dave Emett <david.emett@...adcom.com>

> ---
>  drivers/gpu/drm/v3d/v3d_gem.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index 8a4be9515179..443b1c53117a 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -171,11 +171,15 @@ v3d_invalidate_slices(struct v3d_dev *v3d, int core)
>  void
>  v3d_invalidate_caches(struct v3d_dev *v3d)
>  {
> +       /* Invalidate the caches from the outside in.  That way if
> +        * another CL's concurrent use of nearby memory were to pull
> +        * an invalidated cacheline back in, we wouldn't leave stale
> +        * data in the inner cache.
> +        */
>         v3d_flush_l3(v3d);
> -
>         v3d_invalidate_l2c(v3d, 0);
> -       v3d_invalidate_slices(v3d, 0);
>         v3d_flush_l2t(v3d, 0);
> +       v3d_invalidate_slices(v3d, 0);
>  }
>
>  static void
> --
> 2.20.0.rc1
>