Re: [PATCH v2 2/3] rust: dma: convert the read/write macros to return Result

Danilo Krummrich
2025-04-10T11:54:59Z

On Thu, Apr 10, 2025 at 11:58:17AM +0300, Abdiel Janulgue wrote:
> diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs
> index 874c2c964afa..1e610545e100 100644
> --- a/samples/rust/rust_dma.rs
> +++ b/samples/rust/rust_dma.rs
> @@ -54,13 +54,9 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self
> let ca: CoherentAllocation<MyStruct> =
> CoherentAllocation::alloc_coherent(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?;
>
> - || -> Result {
> - for (i, value) in TEST_VALUES.into_iter().enumerate() {
> - kernel::dma_write!(ca[i] = MyStruct::new(value.0, value.1));
> - }
> -
> - Ok(())
> - }()?;
> + for (i, value) in TEST_VALUES.into_iter().enumerate() {
> + kernel::dma_write!(ca[i] = MyStruct::new(value.0, value.1))?;
> + }
>
> let drvdata = KBox::new(
> Self {
> @@ -78,13 +74,14 @@ impl Drop for DmaSampleDriver {
> fn drop(&mut self) {
> dev_info!(self.pdev.as_ref(), "Unload DMA test driver.\n");
>
> - let _ = || -> Result {
> - for (i, value) in TEST_VALUES.into_iter().enumerate() {
> - assert_eq!(kernel::dma_read!(self.ca[i].h), value.0);
> - assert_eq!(kernel::dma_read!(self.ca[i].b), value.1);
> - }
> - Ok(())
> - }();
> + for (i, value) in TEST_VALUES.into_iter().enumerate() {
> + let val0 = kernel::dma_read!(self.ca[i].h);
> + let val1 = kernel::dma_read!(self.ca[i].b);
> + assert!(val0.is_ok());
> + assert!(val1.is_ok());
> + assert_eq!(val0.unwrap(), value.0);
> + assert_eq!(val1.unwrap(), value.1);

Maybe use if-let to avoid the unwrap?

if let Ok(val0) = val0 {
assert_eq!(val0, value.0);
}

I know it's a bit pointless, since we know it must be ok, but the educational
message of the example should be to check and not to unwrap, so maybe that's
better.