Re: dma_fence: force users to take the lock manually

["Christian König" <christian.koenig@amd.com>]

On 3/5/26 14:54, Philipp Stanner wrote:
> Yo Christian,
> 
> a while ago we were discussing this problem
> 
> dma_fence_set_error(f, -ECANCELED);
> dma_fence_signal(f); // racy!
> 
> 
> I think you mentioned that you are considering to redesign the
> dma_fence API so that users have to take the lock themselves to touch
> the fence:
> 
> dma_fence_lock(f);
> dma_fence_set_error(f, -ECANCELED);
> dma_fence_signal(f);
> dme_fence_unlock(f);
> 
> 
> Is that still up to date? Is there work in progress about that?

It's on my "maybe if I ever have time for that" list, but yeah I think it would be really nice to have and a great cleanup.

We have a bunch of different functions which provide both a _locked() and _unlocked() variant just because callers where to lazy to lock the fence.

Especially the dma_fence_signal function is overloaded 4 (!) times with locked/unlocked and with and without timestamp functions.

> I discovered that I might need / want that for the Rust abstractions.

Well my educated guess is for Rust you only want the locked function and never allow callers to be lazy.

Regards,
Christian.

> 
> 
> Regards,
> P.