Hello Dan,
On Wed, 24 Jun 2020 20:58:06 +0300 Dan Carpenter dan.carpenter@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