diff mbox series

dma-buf: cleanup dma_fence_chain_walk

Message ID 20220518085446.31338-1-christian.koenig@amd.com (mailing list archive)
State Not Applicable
Headers
Series dma-buf: cleanup dma_fence_chain_walk |

Commit Message

Christian König May 18, 2022, 8:54 a.m. UTC 
  Use unrcu_pointer() instead of the manual cast.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-fence-chain.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Daniel Vetter May 25, 2022, 3:18 p.m. UTC | #1 
On Wed, May 18, 2022 at 10:54:46AM +0200, Christian König wrote:
> Use unrcu_pointer() instead of the manual cast.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

TIL about unrcu_pointer, and also that entire code here freaks me out. But
at least this seems more with what other users of similar xchg and cmpxchg
tricks are doing, so that's nice.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/dma-buf/dma-fence-chain.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
> index 06f8ef97c6e8..a0d920576ba6 100644
> --- a/drivers/dma-buf/dma-fence-chain.c
> +++ b/drivers/dma-buf/dma-fence-chain.c
> @@ -62,8 +62,8 @@ struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence)
>  			replacement = NULL;
>  		}
>  
> -		tmp = cmpxchg((struct dma_fence __force **)&chain->prev,
> -			      prev, replacement);
> +		tmp = unrcu_pointer(cmpxchg(&chain->prev, RCU_INITIALIZER(prev),
> +					     RCU_INITIALIZER(replacement)));
>  		if (tmp == prev)
>  			dma_fence_put(tmp);
>  		else
> -- 
> 2.25.1
>
diff mbox series

Patch

diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
index 06f8ef97c6e8..a0d920576ba6 100644
--- a/drivers/dma-buf/dma-fence-chain.c
+++ b/drivers/dma-buf/dma-fence-chain.c
@@ -62,8 +62,8 @@  struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence)
 			replacement = NULL;
 		}
 
-		tmp = cmpxchg((struct dma_fence __force **)&chain->prev,
-			      prev, replacement);
+		tmp = unrcu_pointer(cmpxchg(&chain->prev, RCU_INITIALIZER(prev),
+					     RCU_INITIALIZER(replacement)));
 		if (tmp == prev)
 			dma_fence_put(tmp);
 		else