Quoting Gustavo Padovan (2017-07-29 16:22:16)
From: Gustavo Padovan gustavo.padovan@collabora.com
If userspace already dropped its own reference by closing the sw_sync fence fd we might end up in a deadlock where dma_fence_is_signaled_locked() will trigger the release of the fence and thus try to hold the lock to remove the fence from the list.
dma_fence_is_signaled_locked() tries to release/free the fence and hold the lock in the process.
We fix that by changing the order operation and clean up the list and rb-tree first.
v2: Drop the fence get/put dance and manipulate the list first (Chris Wilson)
Cc: Chris Wilson chris@chris-wilson.co.uk Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.com
Reviewed-by: Chris Wilson chris@chris-wilson.co.uk -Chris