[PATCH] dma-buf/sync_file: Allow multiple sync_files to wrap a single dma-fence

[Gustavo Padovan]

Hi Chris,

2017-07-28 Chris Wilson <chris at chris-wilson.co.uk>:

> Up until recently sync_file were create to export a single dma-fence to
> userspace, and so we could canabalise a bit insie dma-fence to mark
> whether or not we had enable polling for the sync_file itself. However,
> with the advent of syncobj, we do allow userspace to create multiple
> sync_files for a single dma-fence. (Similarly, that the sw-sync
> validation framework also started returning multiple sync-files wrapping
> a single dma-fence for a syncpt also triggering the problem.)
> 
> This patch reverts my suggestion in commit e24165537312
> ("dma-buf/sync_file: only enable fence signalling on poll()") to use a
> single bit in the shared dma-fence and restores the sync_file->flags for
> tracking the bits individually.
> 
> Reported-by: Gustavo Padovan <gustavo at padovan.org>
> Fixes: f1e8c67123cf ("dma-buf/sw-sync: Use an rbtree to sort fences in the timeline")
> Fixes: e9083420bbac ("drm: introduce sync objects (v4)")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal at linaro.org>
> Cc: Sean Paul <seanpaul at chromium.org>
> Cc: Gustavo Padovan <gustavo at padovan.org>
> Cc: dri-devel at lists.freedesktop.org
> Cc: <drm-intel-fixes at lists.freedesktop.org> # v4.13-rc1+
> ---
>  drivers/dma-buf/sync_file.c | 5 +++--
>  include/linux/sync_file.h   | 3 ++-
>  2 files changed, 5 insertions(+), 3 deletions(-)

I confirm the patch fixes the sync kselftests for me. Pushed to
drm-misc-next.

Gustavo