Op 31-10-2019 om 23:36 schreef Rob Clark:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> Stalling on cleanup_done ensures that any atomic state related to a
> nonblock commit no longer has dangling references to per-object state
> that can be freed.
>
> Otherwise, if a !nonblock commit completes after a nonblock commit has
> swapped state (ie. the synchronous part of the nonblock commit comes
> before the !nonblock commit), but before the asynchronous part of the
> nonblock commit completes, what was the new per-object state in the
> nonblock commit can be freed.
>
> This shows up with the new self-refresh helper, as _update_avg_times()
> dereferences the original old and new crtc_state.
>
> Fixes: d4da4e33341c ("drm: Measure Self Refresh Entry/Exit times to avoid thrashing")
> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> ---
> Other possibilities:
> 1) maybe block later before freeing atomic state?
> 2) refcount individual per-object state
>
> drivers/gpu/drm/drm_atomic_helper.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 3ef2ac52ce94..a5d95429f91b 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -2711,7 +2711,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state,
> if (!commit)
> continue;
>
> - ret = wait_for_completion_interruptible(&commit->hw_done);
> + ret = wait_for_completion_interruptible(&commit->cleanup_done);
> if (ret)
> return ret;
> }
> @@ -2722,7 +2722,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state,
> if (!commit)
> continue;
>
> - ret = wait_for_completion_interruptible(&commit->hw_done);
> + ret = wait_for_completion_interruptible(&commit->cleanup_done);
> if (ret)
> return ret;
> }
> @@ -2733,7 +2733,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state,
> if (!commit)
> continue;
>
> - ret = wait_for_completion_interruptible(&commit->hw_done);
> + ret = wait_for_completion_interruptible(&commit->cleanup_done);
> if (ret)
> return ret;
> }
Nack, hw_done means all new_crtc_state (from the old commit pov) dereferences are done.
Self refresh helpers should be fixed. :)
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