[PATCH] drm/vmwgfx: fix lock breakage

[Rob Clark]

On Thu, Oct 30, 2014 at 1:39 PM, Rob Clark <robdclark at gmail.com> wrote:
> After:
>
> commit d059f652e73c35678d28d4cd09ab2cec89696af9
> Author:     Daniel Vetter <daniel.vetter at ffwll.ch>
> AuthorDate: Fri Jul 25 18:07:40 2014 +0200
>
>     drm: Handle legacy per-crtc locking with full acquire ctx
>
> drm_mode_cursor_common() was switched to use drm_modeset_(un)lock_crtc()
> which uses full aquire ctx.  So dropping/reaquiring the lock via
> drm_modeset_(un)lock() directly isn't the right thing to do, as lockdep
> kindly points out.
>
> The 'FIXME's about sorting out whether vmwgfx *really* needs to lock-all
> for cursor updates still apply.
>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1155825

> Signed-off-by: Rob Clark <robdclark at gmail.com>
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index d2bc2b0..8fc1e38 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -187,7 +187,7 @@ int vmw_du_crtc_cursor_set(struct drm_crtc *crtc, struct drm_file *file_priv,
>          * can do this since the caller in the drm core doesn't check anything
>          * which is protected by any looks.
>          */
> -       drm_modeset_unlock(&crtc->mutex);
> +       drm_modeset_unlock_crtc(crtc);
>         drm_modeset_lock_all(dev_priv->dev);
>
>         /* A lot of the code assumes this */
> @@ -252,7 +252,7 @@ int vmw_du_crtc_cursor_set(struct drm_crtc *crtc, struct drm_file *file_priv,
>         ret = 0;
>  out:
>         drm_modeset_unlock_all(dev_priv->dev);
> -       drm_modeset_lock(&crtc->mutex, NULL);
> +       drm_modeset_lock_crtc(crtc);
>
>         return ret;
>  }
> @@ -273,7 +273,7 @@ int vmw_du_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
>          * can do this since the caller in the drm core doesn't check anything
>          * which is protected by any looks.
>          */
> -       drm_modeset_unlock(&crtc->mutex);
> +       drm_modeset_unlock_crtc(crtc);
>         drm_modeset_lock_all(dev_priv->dev);
>
>         vmw_cursor_update_position(dev_priv, shown,
> @@ -281,7 +281,7 @@ int vmw_du_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
>                                    du->cursor_y + du->hotspot_y);
>
>         drm_modeset_unlock_all(dev_priv->dev);
> -       drm_modeset_lock(&crtc->mutex, NULL);
> +       drm_modeset_lock_crtc(crtc);
>
>         return 0;
>  }
> --
> 1.9.3
>