+Cc André
On Thu, 2026-06-25 at 22:12 +0800, Baineng Shou wrote:
> dma_fence_timeline_name() incorrectly invokes ops->get_driver_name()
> instead of ops->get_timeline_name(), so every caller receives the
> driver name where the timeline name was expected.
>
> This is a copy-paste regression that has resurfaced twice. It was
> originally introduced by commit 62918542b7bf ("dma-fence: Fix sparse
> warnings due __rcu annotations") when adding the __rcu casts, fixed
> by commit 033559473dd3 ("dma-fence: Fix safe access wrapper to call
> timeline name method"), and then accidentally reintroduced by commit
> e58b4dea9054 ("dma-buf/dma-fence: Add dma_fence_test_signaled_flag()")
> when both wrappers were refactored to use the new helper.
>
> Signed-off-by: Baineng Shou <[email protected]>
André has caught this a few days ago already:
https://lore.kernel.org/dri-devel/[email protected]/
To save my honor I want to state that e58b4dea9054 did not actually *do
this* change. But merging it must have caused it somehow, since that
commit was still based on the old bug. I guess somewhere in conflict
resolution somehow tho old code must have entered.
P.
> ---
> drivers/dma-buf/dma-fence.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index b3bfa6943a8e..5292d714419b 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -1202,7 +1202,7 @@ const char __rcu *dma_fence_timeline_name(struct
> dma_fence *fence)
> /* RCU protection is required for safe access to returned string */
> ops = rcu_dereference(fence->ops);
> if (!dma_fence_test_signaled_flag(fence))
> - return (const char __rcu *)ops->get_driver_name(fence);
> + return (const char __rcu *)ops->get_timeline_name(fence);
> else
> return (const char __rcu *)"signaled-timeline";
> }
