Re: [PATCH 1/6] drm/dp_mst: Introduce drm_dp_mst_connector_atomic_check()

Dan Carpenter
2018-09-20T09:16:51Z

Hi Lyude,

Thank you for the patch! Perhaps something to improve:

url: https://github.com/0day-ci/linux/commits/Lyude-Paul/Fix-legacy-DPMS-changes-with-MST/20180919-203434
base: git://anongit.freedesktop.org/drm-intel for-linux-next

smatch warnings:
drivers/gpu/drm/drm_dp_mst_topology.c:3144 drm_dp_mst_connector_still_exists() error: we previously assumed 'port' could be null (see line 3146)

# https://github.com/0day-ci/linux/commit/f8df31d5221b9a6da6698d4a37e622253bb17cdc
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout f8df31d5221b9a6da6698d4a37e622253bb17cdc
vim +/port +3144 drivers/gpu/drm/drm_dp_mst_topology.c

3f3353b7 Pandiyan, Dhinakaran 2017-04-20 3131
f8df31d5 Lyude Paul 2018-09-18 3132 static bool
f8df31d5 Lyude Paul 2018-09-18 3133 drm_dp_mst_connector_still_exists(struct drm_connector *connector,
f8df31d5 Lyude Paul 2018-09-18 3134 struct drm_dp_mst_topology_mgr *mgr,
f8df31d5 Lyude Paul 2018-09-18 3135 struct drm_dp_mst_branch *mstb)
f8df31d5 Lyude Paul 2018-09-18 3136 {
f8df31d5 Lyude Paul 2018-09-18 3137 struct drm_dp_mst_port *port;
f8df31d5 Lyude Paul 2018-09-18 3138 bool exists = false;
f8df31d5 Lyude Paul 2018-09-18 3139
f8df31d5 Lyude Paul 2018-09-18 3140 mstb = drm_dp_get_validated_mstb_ref(mgr, mstb);
f8df31d5 Lyude Paul 2018-09-18 3141 if (!mstb)
f8df31d5 Lyude Paul 2018-09-18 3142 return false;
f8df31d5 Lyude Paul 2018-09-18 3143
f8df31d5 Lyude Paul 2018-09-18 @3144 list_for_each_entry(port, &mstb->ports, next) {
^^^^
We need to use a different loop iterator, or possibly
list_for_each_entry_safe() because it looks like we're freeing
something. Maybe it's cleanest to do both.

f8df31d5 Lyude Paul 2018-09-18 3145 port = drm_dp_get_validated_port_ref(mgr, port);
f8df31d5 Lyude Paul 2018-09-18 @3146 if (!port)
f8df31d5 Lyude Paul 2018-09-18 3147 continue;
f8df31d5 Lyude Paul 2018-09-18 3148
f8df31d5 Lyude Paul 2018-09-18 3149 exists = (port->connector == connector ||
f8df31d5 Lyude Paul 2018-09-18 3150 (port->mstb &&
f8df31d5 Lyude Paul 2018-09-18 3151 drm_dp_mst_connector_still_exists(connector, mgr,
f8df31d5 Lyude Paul 2018-09-18 3152 port->mstb)));
f8df31d5 Lyude Paul 2018-09-18 3153
f8df31d5 Lyude Paul 2018-09-18 3154 drm_dp_put_port(port);
f8df31d5 Lyude Paul 2018-09-18 3155 if (exists)
f8df31d5 Lyude Paul 2018-09-18 3156 break;
f8df31d5 Lyude Paul 2018-09-18 3157 }
f8df31d5 Lyude Paul 2018-09-18 3158
f8df31d5 Lyude Paul 2018-09-18 3159 drm_dp_put_mst_branch_device(mstb);
f8df31d5 Lyude Paul 2018-09-18 3160 return exists;
f8df31d5 Lyude Paul 2018-09-18 3161 }
f8df31d5 Lyude Paul 2018-09-18 3162

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