There is no need to look at the port's VCPI allocation before calling
drm_dp_mst_deallocate_vcpi(), as we already have msto->disabled to let
us avoid cleaning up an msto more then once. The DP MST core will never
call drm_dp_mst_deallocate_vcpi() on it's own, which is presumably what
these checks are meant to protect against.
More importantly though, we're about to stop clearing mstc->port in the
next commit, which means if we could potentially hit a use-after-free
error if we tried to check mstc->port->vcpi here. So to make life easier
for anyone who bisects this code in the future, use msto->disabled
instead to check whether or not we need to deallocate VCPI instead.
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Reviewed-By: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxxx>
Cc: Jerry Zuo <Jerry.Zuo@xxxxxxx>
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Juston Li <juston.li@xxxxxxxxx>
---
drivers/gpu/drm/nouveau/dispnv50/disp.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 800213be76ea..28538ef19b71 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -703,14 +703,17 @@ nv50_msto_cleanup(struct nv50_msto *msto)
struct nv50_mstc *mstc = msto->mstc;
struct nv50_mstm *mstm = mstc->mstm;
+ if (!msto->disabled)
+ return;
+
NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
- if (mstc->port && mstc->port->vcpi.vcpi > 0 && !nv50_msto_payload(msto))
+
+ if (mstc->port)
drm_dp_mst_deallocate_vcpi(&mstm->mgr, mstc->port);
- if (msto->disabled) {
- msto->mstc = NULL;
- msto->head = NULL;
- msto->disabled = false;
- }
+
+ msto->mstc = NULL;
+ msto->head = NULL;
+ msto->disabled = false;
}
static void
--
2.20.1
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