The addition of ww_acquire_done() call to mark the point where all locks
should already be held, added in:
commit 992cbf19b32900efa17850b9fa0031fd623edd4d
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
AuthorDate: Thu Aug 6 15:06:40 2015 +0200
drm/atomic: Call ww_acquire_done after check phase is complete
missed the case that legacy paths (which are already called between
drm_modeset_lock_all()/unlock_all()) re-use the single acquire ctx, even
if there are multiple atomic updates. For example, restore_fbdev_mode()
clearing rotation properties individually on each plane.
Inki already sent a patch which completely removed the ww_acquire_done()
call, but I think this is less ideal (since it is a nice debugging
feature of ww_mutex to confirm that everyone is following the rules).
So instead, just skip the call only in the special legacy-path case.
Reported-by: Inki Dae <inki.dae@xxxxxxxxxxx>
Tested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
Signed-off-by: Rob Clark <robdclark@xxxxxxxxx>
---
drivers/gpu/drm/drm_atomic.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 1066e4b..b90068c 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1230,8 +1230,15 @@ int drm_atomic_check_only(struct drm_atomic_state *state)
}
}
- if (ret == 0)
- ww_acquire_done(&state->acquire_ctx->ww_ctx);
+ if (ret == 0) {
+ /* in legacy paths, there can be multiple atomic updates,
+ * such as drm_mode_plane_set_obj_prop(), which happen
+ * under a single drm_modeset_lock_all(). In the legacy
+ * paths, skip marking acquire-done lest we anger ww-mutex:
+ */
+ if (state->acquire_ctx != dev->mode_config.acquire_ctx)
+ ww_acquire_done(&state->acquire_ctx->ww_ctx);
+ }
return ret;
}
--
2.4.3
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