Hello Dan,
On Wed, 24 Jun 2020 20:58:06 +0300
Dan Carpenter <dan.carpenter at oracle.com> wrote:
> Hello Boris Brezillon,
>
> The patch 033bfe7538a1: "drm/vc4: dsi: Fix bridge chain handling"
> from Dec 27, 2019, leads to the following static checker warning:
>
> drivers/gpu/drm/vc4/vc4_dsi.c:758 vc4_dsi_encoder_disable()
> warn: iterator used outside loop: 'iter'
>
> drivers/gpu/drm/vc4/vc4_dsi.c
> 743 static void vc4_dsi_encoder_disable(struct drm_encoder *encoder)
> 744 {
> 745 struct vc4_dsi_encoder *vc4_encoder = to_vc4_dsi_encoder(encoder);
> 746 struct vc4_dsi *dsi = vc4_encoder->dsi;
> 747 struct device *dev = &dsi->pdev->dev;
> 748 struct drm_bridge *iter;
> 749
> 750 list_for_each_entry_reverse(iter, &dsi->bridge_chain, chain_node) {
> 751 if (iter->funcs->disable)
> 752 iter->funcs->disable(iter);
> 753 }
>
> This loops backwards until iter is parked on the list head.
>
> 754
> 755 vc4_dsi_ulps(dsi, true);
> 756
> 757 list_for_each_entry_from(iter, &dsi->bridge_chain, chain_node) {
>
> But then this "continues" until the iter is parked on the list head.
> Since we ended with the iterator already on the list head then we never
> enter this loop and it is a no-op.
>
> Am I missing something?
It should definitely be list_for_each_entry() here. Thanks for
this report. Would you mind sending a patch?
Regards,
Boris