Re: [PATCH v2 0/6] rust / dma_buf: Add abstractions for dma_fence

["Danilo Krummrich" <dakr@kernel.org>]

On Tue Jun 16, 2026 at 10:28 AM CEST, Philipp Stanner wrote:
> Changes since v1:

It seems that some of the comments from v1 [1][2] are not addressed, did you
forget them?

In particular the pin_init_from_closure() looks unnecessary and can probably
replaced with something like (untested):

	let mut callback = Some(callback);
	
	try_pin_init!(Self {
	    cb <- Opaque::try_ffi_init(|ptr| {
	        // SAFETY: `fence.inner.get()` is a valid, initialized `struct dma_fence`. `ptr`
	        // points to the `struct dma_fence_cb` field within the pinned allocation, so it
	        // remains valid until `dma_fence_remove_callback()` in `PinnedDrop` or until the
	        // callback fires.
	        let ret = unsafe {
	            to_result(bindings::dma_fence_add_callback(
	                fence.inner.get(),
	                ptr,
	                Some(Self::dma_fence_callback),
	            ))
	        };
	        match ret {
	            Ok(()) => Ok(()),
	            Err(e) => {
	                let cb_back = callback.take().expect("success path did not run");
	                if e == ENOENT {
	                    Err(CallbackError::AlreadySignaled(cb_back))
	                } else {
	                    Err(CallbackError::Other(e))
	                }
	            }
	        }
	    }),
	    callback: callback.take().expect("error path did not run"),
	    fence: ARef::from(fence),
	}? CallbackError<T>)

Please also see my previous comments regarding DriverFenceBorrow, it still seems
to miss the lifetime and it should probably use ManuallyDrop<DriverFence>.

It also seems the patch series was created without --base, what's the base
revision?

[1] https://lore.kernel.org/all/DIW3ZK5NLKU3.1QYMQB0ISHFBG@kernel.org/
[2] https://lore.kernel.org/all/DIW42TO5HY6H.2RLL8V8H48A5A@kernel.org/