[PATCH v2 3/4] drm/dp_mst: Check payload count in drm_dp_mst_atomic_check()

[Lyude Paul <lyude@redhat.com>]

It occurred to me that we never actually check this! So let's start
doing that.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index dcfab7536914..8bb03700e199 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3238,7 +3238,7 @@ int drm_dp_mst_atomic_check(struct drm_dp_mst_topology_state *state)
 {
 	struct drm_dp_mst_topology_mgr *mgr = state->mgr;
 	struct drm_dp_vcpi_allocation *pos;
-	int avail_slots = 63;
+	int avail_slots = 63, payload_count = 0;
 
 	list_for_each_entry(pos, &state->vcpis, next) {
 		DRM_DEBUG_ATOMIC("[MST PORT:%p] requires %d vcpi slots\n",
@@ -3251,6 +3251,12 @@ int drm_dp_mst_atomic_check(struct drm_dp_mst_topology_state *state)
 					 avail_slots + pos->vcpi);
 			return -ENOSPC;
 		}
+
+		if (++payload_count > mgr->max_payloads) {
+			DRM_DEBUG_ATOMIC("[MST MGR:%p] state %p has too many payloads (max=%d)\n",
+					 mgr, state, mgr->max_payloads);
+			return -EINVAL;
+		}
 	}
 	DRM_DEBUG_ATOMIC("[MST MGR:%p] state %p vcpi avail=%d used=%d\n",
 			 mgr, state, avail_slots, 63 - avail_slots);
-- 
2.17.2

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