Re: [PATCH] drm/crtc: fix uninitialized variable use even harder

[Rob Clark]

On Mon, Feb 12, 2024 at 1:55 PM Rob Clark <robdclark@xxxxxxxxx> wrote:
>
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> DRM_MODESET_LOCK_ALL_BEGIN() has a hidden trap-door (aka retry loop),
> which means we can't rely too much on variable initializers.
>
> Fixes: 6e455f5dcdd1 ("drm/crtc: fix uninitialized variable use")
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> ---
> I have mixed feelings about DRM_MODESET_LOCK_ALL_BEGIN() (and friends)
> magic.  On one hand it simplifies the deadlock/back dance.  OTOH it
> conceals a nasty sharp edge.  Maybe it is better to have the complicated
> restart path a bit more explicit, like it was originally.

I should also point out, had drm-misc-next been using gitlab MRs and
gitlab CI, we would have caught this ;-)

BR,
-R

>  drivers/gpu/drm/drm_crtc.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index cb90e70d85e8..65f9f66933bb 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -904,6 +904,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
>         connector_set = NULL;
>         fb = NULL;
>         mode = NULL;
> +       num_connectors = 0;
>
>         DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
>
> --
> 2.43.0
>