The legacy plane->fb pointer is refcounted by calling
drm_atomic_clean_old_fb().
In practice this isn't a real problem because:
- The caller in the i915 gpu reset code restores the original state
again, which means the plane->fb pointer won't change, hence can't
leak.
- Drivers using drm_atomic_helper_shutdown call the fbdev cleanup
first, and that usually cleans up the fb through
drm_remove_framebuffer, which does this correctly.
- Without fbdev the only framebuffers are from userspace, and those
get cleaned up (again using drm_remove_framebuffer) befor the driver
can even be unloaded.
But in i915 I've switched the cleanup sequence around so that the
_shutdown() calls happens after the drm_remove_framebuffer(), which is
how I discovered this issue.
v2: My analysis why the current code was ok for gpu reset and
suspend/resume was correct, but then I totally failed to realize that
we better keep this symmetric. Thanksfully CI noticed that for
balance, a refcounting bug must exist at 2 places if previously there
was no issue ...
v3: Don't be lazy and compute the plane_mask in
commit_duplicated_state properly too, instead of just using ~0U.
Cc: martin.peres@xxxxxxx
Cc: chris@xxxxxxxxxxxxxxxxxx
Acked-by: Dave Airlie <airlied@xxxxxxxxx> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/gpu/drm/drm_atomic_helper.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index b07fc30372d3..545328a9a769 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2726,6 +2726,7 @@ int drm_atomic_helper_disable_all(struct drm_device *dev,
struct drm_plane *plane;
struct drm_crtc_state *crtc_state;
struct drm_crtc *crtc;
+ unsigned plane_mask = 0;
int ret, i;
state = drm_atomic_state_alloc(dev);
@@ -2768,10 +2769,14 @@ int drm_atomic_helper_disable_all(struct drm_device *dev,
goto free;
drm_atomic_set_fb_for_plane(plane_state, NULL);
+ plane_mask |= BIT(drm_plane_index(plane));
+ plane->old_fb = plane->fb;
}
ret = drm_atomic_commit(state);
free:
+ if (plane_mask)
+ drm_atomic_clean_old_fb(dev, plane_mask, ret);
drm_atomic_state_put(state);
return ret;
}
@@ -2902,11 +2907,16 @@ int drm_atomic_helper_commit_duplicated_state(struct drm_atomic_state *state,
struct drm_connector_state *new_conn_state;
struct drm_crtc *crtc;
struct drm_crtc_state *new_crtc_state;
+ unsigned plane_mask = 0;
+ struct drm_device *dev = state->dev;
+ int ret;
state->acquire_ctx = ctx;
- for_each_new_plane_in_state(state, plane, new_plane_state, i)
+ for_each_new_plane_in_state(state, plane, new_plane_state, i) {
+ plane_mask |= BIT(drm_plane_index(plane));
state->planes[i].old_state = plane->state;
+ }
for_each_new_crtc_in_state(state, crtc, new_crtc_state, i)
state->crtcs[i].old_state = crtc->state;
@@ -2914,7 +2924,11 @@ int drm_atomic_helper_commit_duplicated_state(struct drm_atomic_state *state,
for_each_new_connector_in_state(state, connector, new_conn_state, i)
state->connectors[i].old_state = connector->state;
- return drm_atomic_commit(state);
+ ret = drm_atomic_commit(state);
+ if (plane_mask)
+ drm_atomic_clean_old_fb(dev, plane_mask, ret);
+
+ return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_commit_duplicated_state);
--
2.13.2
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