Re: [PATCH 8/8] dma-buf: use inline lock for the dma-fence-chain

[Boris Brezillon <boris.brezillon@collabora.com>]

On Tue, 10 Feb 2026 11:02:03 +0100
"Christian König" <ckoenig.leichtzumerken@gmail.com> wrote:

> Using the inline lock is now the recommended way for dma_fence
> implementations.
> 
> So use this approach for the framework's internal fences as well.
> 
> Also saves about 4 bytes for the external spinlock.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
> Reviewed-by: Philipp Stanner <phasta@kernel.org>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/dma-buf/dma-fence-chain.c | 3 +--
>  include/linux/dma-fence-chain.h   | 1 -
>  2 files changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
> index a8a90acf4f34..a707792b6025 100644
> --- a/drivers/dma-buf/dma-fence-chain.c
> +++ b/drivers/dma-buf/dma-fence-chain.c
> @@ -245,7 +245,6 @@ void dma_fence_chain_init(struct dma_fence_chain *chain,
>  	struct dma_fence_chain *prev_chain = to_dma_fence_chain(prev);
>  	uint64_t context;
>  
> -	spin_lock_init(&chain->lock);
>  	rcu_assign_pointer(chain->prev, prev);
>  	chain->fence = fence;
>  	chain->prev_seqno = 0;
> @@ -261,7 +260,7 @@ void dma_fence_chain_init(struct dma_fence_chain *chain,
>  			seqno = max(prev->seqno, seqno);
>  	}
>  
> -	dma_fence_init64(&chain->base, &dma_fence_chain_ops, &chain->lock,
> +	dma_fence_init64(&chain->base, &dma_fence_chain_ops, NULL,
>  			 context, seqno);
>  
>  	/*
> diff --git a/include/linux/dma-fence-chain.h b/include/linux/dma-fence-chain.h
> index 68c3c1e41014..d39ce7a2e599 100644
> --- a/include/linux/dma-fence-chain.h
> +++ b/include/linux/dma-fence-chain.h
> @@ -46,7 +46,6 @@ struct dma_fence_chain {
>  		 */
>  		struct irq_work work;
>  	};
> -	spinlock_t lock;
>  };
>  
>