From 270b48bb8da7452b4357d8726933beba72652310 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Wed, 19 Jan 2022 14:37:41 +0100 Subject: [PATCH] dma-buf: Warn about dma_fence_chain container rules v2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. v2: fix comment style Signed-off-by: Christian König Reviewed-by: Daniel Vetter Reviewed-by: Thomas Hellström Link: https://patchwork.freedesktop.org/patch/msgid/20220204100429.2049-4-christian.koenig@amd.com --- drivers/dma-buf/dma-fence-chain.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c index 1b4cb3e5cec9..084c6927b735 100644 --- a/drivers/dma-buf/dma-fence-chain.c +++ b/drivers/dma-buf/dma-fence-chain.c @@ -254,5 +254,14 @@ 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)); } EXPORT_SYMBOL(dma_fence_chain_init);