On Wed, Jan 19, 2022 at 02:43:38PM +0100, Christian König wrote: > Chaining of dma_fence_chain objects is only allowed through the prev > fence and not through the contained fence. > > Warn about that when we create a dma_fence_chain. > > Signed-off-by: Christian König <christian.koenig@xxxxxxx> > --- > drivers/dma-buf/dma-fence-chain.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c > index 1b4cb3e5cec9..fa33f6b7f77b 100644 > --- a/drivers/dma-buf/dma-fence-chain.c > +++ b/drivers/dma-buf/dma-fence-chain.c > @@ -254,5 +254,13 @@ void dma_fence_chain_init(struct dma_fence_chain *chain, > > dma_fence_init(&chain->base, &dma_fence_chain_ops, > &chain->lock, context, seqno); > + > + /* Chaining dma_fence_chain container together is only allowed through > + * the prev fence and not through the contained fence. > + * > + * The correct way of handling this is to flatten out the fence > + * structure into a dma_fence_array by the caller instead. > + */ > + WARN_ON(dma_fence_is_chain(fence)); At first I was worried that you'd leave a chain fence in the array fence as an option, but we exclude that with the previous patch. Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > } > EXPORT_SYMBOL(dma_fence_chain_init); > -- > 2.25.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
