From 2ec86535555c0e748443c1f07087c088b645a9d5 Mon Sep 17 00:00:00 2001 From: Matthew Brost Date: Tue, 24 Feb 2026 10:39:21 -0800 Subject: [PATCH] dma-buf: Assign separate lockdep class to chain lock MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit dma_fence_chain_enable_signaling() and runs while holding the chain inline_lock and may add callbacks to underlying fences, which takes their inline_lock. Since both locks share the same lockdep class, this valid nesting triggers a recursive locking warning. Assign a distinct lockdep class to the chain inline_lock so lockdep can correctly model the hierarchy. Fixes: a408c0ca0c41 ("dma-buf: use inline lock for the dma-fence-chain") Cc: Christian König Cc: Tvrtko Ursulin Cc: Philipp Stanner Cc: Boris Brezillon Signed-off-by: Matthew Brost Reviewed-by: Christian König Link: https://patch.msgid.link/20260224183922.2256492-1-matthew.brost@intel.com --- drivers/dma-buf/dma-fence-chain.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c index a707792b6025a..a588f55ea4d3d 100644 --- a/drivers/dma-buf/dma-fence-chain.c +++ b/drivers/dma-buf/dma-fence-chain.c @@ -242,6 +242,7 @@ void dma_fence_chain_init(struct dma_fence_chain *chain, struct dma_fence *fence, uint64_t seqno) { + static struct lock_class_key dma_fence_chain_lock_key; struct dma_fence_chain *prev_chain = to_dma_fence_chain(prev); uint64_t context; @@ -263,6 +264,18 @@ void dma_fence_chain_init(struct dma_fence_chain *chain, dma_fence_init64(&chain->base, &dma_fence_chain_ops, NULL, context, seqno); + /* + * dma_fence_chain_enable_signaling() is invoked while holding + * chain->base.inline_lock and may call dma_fence_add_callback() + * on the underlying fences, which takes their inline_lock. + * + * Since both locks share the same lockdep class, this legitimate + * nesting confuses lockdep and triggers a recursive locking + * warning. Assign a separate lockdep class to the chain lock + * to model this hierarchy correctly. + */ + lockdep_set_class(&chain->base.inline_lock, &dma_fence_chain_lock_key); + /* * Chaining dma_fence_chain container together is only allowed through * the prev fence and not through the contained fence. -- 2.53.0