[PATCH v2] rust/list: replace unwrap() with ? in doctest examples

[PATCH v2] rust/list: replace unwrap() with ? in doctest examples

[Albin Babu Varghese]

Using `unwrap()` in kernel doctests can cause panics on error and may
give newcomers the mistaken impression that panicking is acceptable
in kernel code.

Replace all `.unwrap()` calls in `kernel::list`
examples with `.ok_or(EINVAL)?` so that errors are properly propagated.

Closes: https://github.com/Rust-for-Linux/linux/issues/1164
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1164
Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
---
Changes in v2:
- Fixed patch formatting issues
- Link to v1: https://lore.kernel.org/rust-for-linux/20250525225925.14797-1-albinbabuvarghese20@gmail.com/ 
---
 rust/kernel/list.rs | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/rust/kernel/list.rs b/rust/kernel/list.rs
index c391c30b80f8..fe58a3920e70 100644
--- a/rust/kernel/list.rs
+++ b/rust/kernel/list.rs
@@ -82,9 +82,9 @@
 /// // [15, 10, 30]
 /// {
 ///     let mut iter = list.iter();
-///     assert_eq!(iter.next().unwrap().value, 15);
-///     assert_eq!(iter.next().unwrap().value, 10);
-///     assert_eq!(iter.next().unwrap().value, 30);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 15);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 10);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 30);
 ///     assert!(iter.next().is_none());
 ///
 ///     // Verify the length of the list.
@@ -93,9 +93,9 @@
 ///
 /// // Pop the items from the list using `pop_back()` and verify the content.
 /// {
-///     assert_eq!(list.pop_back().unwrap().value, 30);
-///     assert_eq!(list.pop_back().unwrap().value, 10);
-///     assert_eq!(list.pop_back().unwrap().value, 15);
+///     assert_eq!(list.pop_back().ok_or(EINVAL)?.value, 30);
+///     assert_eq!(list.pop_back().ok_or(EINVAL)?.value, 10);
+///     assert_eq!(list.pop_back().ok_or(EINVAL)?.value, 15);
 /// }
 ///
 /// // Insert 3 elements using `push_front()`.
@@ -107,9 +107,9 @@
 /// // [30, 10, 15]
 /// {
 ///     let mut iter = list.iter();
-///     assert_eq!(iter.next().unwrap().value, 30);
-///     assert_eq!(iter.next().unwrap().value, 10);
-///     assert_eq!(iter.next().unwrap().value, 15);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 30);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 10);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 15);
 ///     assert!(iter.next().is_none());
 ///
 ///     // Verify the length of the list.
@@ -118,8 +118,8 @@
 ///
 /// // Pop the items from the list using `pop_front()` and verify the content.
 /// {
-///     assert_eq!(list.pop_front().unwrap().value, 30);
-///     assert_eq!(list.pop_front().unwrap().value, 10);
+///     assert_eq!(list.pop_front().ok_or(EINVAL)?.value, 30);
+///     assert_eq!(list.pop_front().ok_or(EINVAL)?.value, 10);
 /// }
 ///
 /// // Push `list2` to `list` through `push_all_back()`.
@@ -135,9 +135,9 @@
 ///     // list: [15, 25, 35]
 ///     // list2: []
 ///     let mut iter = list.iter();
-///     assert_eq!(iter.next().unwrap().value, 15);
-///     assert_eq!(iter.next().unwrap().value, 25);
-///     assert_eq!(iter.next().unwrap().value, 35);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 15);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 25);
+///     assert_eq!(iter.next().ok_or(EINVAL)?.value, 35);
 ///     assert!(iter.next().is_none());
 ///     assert!(list2.is_empty());
 /// }
@@ -809,11 +809,11 @@ fn next(&mut self) -> Option<ArcBorrow<'a, T>> {
 /// merge_sorted(&mut list, list2);
 ///
 /// let mut items = list.into_iter();
-/// assert_eq!(items.next().unwrap().value, 10);
-/// assert_eq!(items.next().unwrap().value, 11);
-/// assert_eq!(items.next().unwrap().value, 12);
-/// assert_eq!(items.next().unwrap().value, 13);
-/// assert_eq!(items.next().unwrap().value, 14);
+/// assert_eq!(items.next().ok_or(EINVAL)?.value, 10);
+/// assert_eq!(items.next().ok_or(EINVAL)?.value, 11);
+/// assert_eq!(items.next().ok_or(EINVAL)?.value, 12);
+/// assert_eq!(items.next().ok_or(EINVAL)?.value, 13);
+/// assert_eq!(items.next().ok_or(EINVAL)?.value, 14);
 /// assert!(items.next().is_none());
 /// # Result::<(), Error>::Ok(())
 /// ```
--- 
Thanks,
Albin

Re: [PATCH v2] rust/list: replace unwrap() with ? in doctest examples

[Alice Ryhl]

On Tue, May 27, 2025 at 04:49:28PM -0400, Albin Babu Varghese wrote:
> Using `unwrap()` in kernel doctests can cause panics on error and may
> give newcomers the mistaken impression that panicking is acceptable
> in kernel code.
> 
> Replace all `.unwrap()` calls in `kernel::list`
> examples with `.ok_or(EINVAL)?` so that errors are properly propagated.
> 
> Closes: https://github.com/Rust-for-Linux/linux/issues/1164
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Reviewed-by: Benno Lossin <lossin@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/1164
> Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

Re: [PATCH v2] rust/list: replace unwrap() with ? in doctest examples

[Danilo Krummrich]

On 5/27/25 10:49 PM, Albin Babu Varghese wrote:
> Using `unwrap()` in kernel doctests can cause panics on error and may
> give newcomers the mistaken impression that panicking is acceptable
> in kernel code.
> 
> Replace all `.unwrap()` calls in `kernel::list`
> examples with `.ok_or(EINVAL)?` so that errors are properly propagated.
> 
> Closes: https://github.com/Rust-for-Linux/linux/issues/1164
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Reviewed-by: Benno Lossin <lossin@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/1164
> Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>

Reviewed-by: Danilo Krummrich <dakr@kernel.org>

Re: [PATCH v2] rust/list: replace unwrap() with ? in doctest examples

[Albin Babu Varghese]

Thank you Alice and Danilo for reviewing the patch.

---
Cheers,
Albin

Re: [PATCH v2] rust/list: replace unwrap() with ? in doctest examples

[Miguel Ojeda]

On Tue, May 27, 2025 at 10:52 PM Albin Babu Varghese
<albinbabuvarghese20@gmail.com> wrote:
>
> Using `unwrap()` in kernel doctests can cause panics on error and may
> give newcomers the mistaken impression that panicking is acceptable
> in kernel code.
>
> Replace all `.unwrap()` calls in `kernel::list`
> examples with `.ok_or(EINVAL)?` so that errors are properly propagated.
>
> Closes: https://github.com/Rust-for-Linux/linux/issues/1164
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Reviewed-by: Benno Lossin <lossin@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/1164
> Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>

Applied to `rust-next` -- thanks everyone!

    [ Reworded slightly. - Miguel ]

Cheers,
Miguel