[PATCH v3 00/12] rust: kernel: documentation improvements

[PATCH v3 00/12] rust: kernel: documentation improvements

[Valentin Obst via B4 Relay]

This patch set aims to make small improvements to the documentation of
the kernel crate. It engages in a few different activities:
- fixing trivial typos (commit #1),
- updating code examples to better reflect an idiomatic coding style
  (commits #2,6),
- increasing the consistency within the crate's documentation as a whole
  (commits #3,5,7,8,9,11,12),
- adding more intra-doc links as well as srctree-relative links to C
  header files (commits #4,10).

---
Changes in v3:
- Adjusted word wrapping in "rust: locked_by: shorten doclink preview"
  to make use of the gained space.
- Rebased with `rust-next`.
- Link to v2: https://lore.kernel.org/lkml/20240123150112.124084-1-kernel@valentinobst.de/
Changes in v2:
- Drop commit "rust: kernel: add doclinks with html tags" in response to
  review.
- Fix another list item alignment issue pointed out during review of v1.
  Was added to commit "rust: kernel: fix multiple typos in
  documentation".
- Commit "rust: error: move unsafe block into function call" is now
  "rust: error: improve unsafe code in example" and also rewords the
  SAFETY comment of the code example.
  - Did not add 'Reviewed-By' tags offered in v1 tags due to changes.
- Link to v1: https://lore.kernel.org/lkml/20240116160141.165951-1-kernel@valentinobst.de/

---
Valentin Obst (12):
      rust: kernel: fix multiple typos in documentation
      rust: error: improve unsafe code in example
      rust: ioctl: end top-level module docs with full stop
      rust: kernel: add srctree-relative doclinks
      rust: str: use `NUL` instead of 0 in doc comments
      rust: str: move SAFETY comment in front of unsafe block
      rust: kernel: unify spelling of refcount in docs
      rust: kernel: mark code fragments in docs with backticks
      rust: kernel: add blank lines in front of code blocks
      rust: kernel: add doclinks
      rust: kernel: remove unneeded doclink targets
      rust: locked_by: shorten doclink preview

 rust/kernel/allocator.rs          |  2 +-
 rust/kernel/error.rs              | 10 ++----
 rust/kernel/init.rs               | 16 +++++-----
 rust/kernel/ioctl.rs              |  6 ++--
 rust/kernel/lib.rs                |  2 +-
 rust/kernel/str.rs                |  8 ++---
 rust/kernel/sync/arc.rs           | 14 ++++-----
 rust/kernel/sync/condvar.rs       |  2 ++
 rust/kernel/sync/lock.rs          | 15 ++++++---
 rust/kernel/sync/lock/spinlock.rs |  2 +-
 rust/kernel/sync/locked_by.rs     |  7 +++--
 rust/kernel/task.rs               |  6 ++--
 rust/kernel/types.rs              |  3 ++
 rust/kernel/workqueue.rs          | 64 +++++++++++++++++++--------------------
 14 files changed, 84 insertions(+), 73 deletions(-)
---
base-commit: f090f0d0eea9666a96702b29bc9a64cbabee85c5
change-id: 20240131-doc-fixes-v3-88af6c8c1777

Best regards,
-- 
Valentin Obst <kernel@valentinobst.de>

[PATCH v3 01/12] rust: kernel: fix multiple typos in documentation

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Fixes multiple trivial typos in documentation and comments of the
kernel crate.

allocator:
- Fix a trivial list item alignment issue in the last SAFETY comment of
  `krealloc_aligned`.

init:
- Replace 'type' with 'trait' in the doc comments of the `PinInit` and
  `Init` traits.
- Add colons before starting lists.
- Add spaces between the type and equal sign to respect the code
  formatting rules in example code.
- End a sentence with a full stop instead of a colon.

ioctl:
- Replace 'an' with 'a' where appropriate.

str:
- Replace 'Return' with 'Returns' in the doc comment of `bytes_written`
  as the text describes what the function does.

sync/lock:
- Fix a trivial list item alignment issue in the Safety section of the
  `Backend` trait's description.

sync/lock/spinlock:
- The code in this module operates on spinlocks, not mutexes. Thus,
  replace 'mutex' with 'spinlock' in the SAFETY comment of `unlock`.

workqueue:
- Replace "wont" with "won't" in the doc comment of `__enqueue`.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/allocator.rs          |  2 +-
 rust/kernel/init.rs               | 16 ++++++++--------
 rust/kernel/ioctl.rs              |  4 ++--
 rust/kernel/str.rs                |  2 +-
 rust/kernel/sync/lock.rs          |  4 ++--
 rust/kernel/sync/lock/spinlock.rs |  2 +-
 rust/kernel/workqueue.rs          |  2 +-
 7 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
index 4b057e837358..01ad139e19bc 100644
--- a/rust/kernel/allocator.rs
+++ b/rust/kernel/allocator.rs
@@ -35,7 +35,7 @@ unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gf
     // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
     //   function safety requirement.
     // - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
-    //    according to the function safety requirement) or a result from `next_power_of_two()`.
+    //   according to the function safety requirement) or a result from `next_power_of_two()`.
     unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 }
 }
 
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 65be9ae57b80..16a99984622c 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -751,10 +751,10 @@ macro_rules! try_init {
 ///
 /// # Safety
 ///
-/// When implementing this type you will need to take great care. Also there are probably very few
+/// When implementing this trait you will need to take great care. Also there are probably very few
 /// cases where a manual implementation is necessary. Use [`pin_init_from_closure`] where possible.
 ///
-/// The [`PinInit::__pinned_init`] function
+/// The [`PinInit::__pinned_init`] function:
 /// - returns `Ok(())` if it initialized every field of `slot`,
 /// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means:
 ///     - `slot` can be deallocated without UB occurring,
@@ -861,10 +861,10 @@ unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
 ///
 /// # Safety
 ///
-/// When implementing this type you will need to take great care. Also there are probably very few
+/// When implementing this trait you will need to take great care. Also there are probably very few
 /// cases where a manual implementation is necessary. Use [`init_from_closure`] where possible.
 ///
-/// The [`Init::__init`] function
+/// The [`Init::__init`] function:
 /// - returns `Ok(())` if it initialized every field of `slot`,
 /// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means:
 ///     - `slot` can be deallocated without UB occurring,
@@ -1013,7 +1013,7 @@ pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> {
 ///
 /// ```rust
 /// use kernel::{error::Error, init::init_array_from_fn};
-/// let array: Box<[usize; 1_000]>= Box::init::<Error>(init_array_from_fn(|i| i)).unwrap();
+/// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i)).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
 pub fn init_array_from_fn<I, const N: usize, T, E>(
@@ -1027,7 +1027,7 @@ pub fn init_array_from_fn<I, const N: usize, T, E>(
         // Counts the number of initialized elements and when dropped drops that many elements from
         // `slot`.
         let mut init_count = ScopeGuard::new_with_data(0, |i| {
-            // We now free every element that has been initialized before:
+            // We now free every element that has been initialized before.
             // SAFETY: The loop initialized exactly the values from 0..i and since we
             // return `Err` below, the caller will consider the memory at `slot` as
             // uninitialized.
@@ -1056,7 +1056,7 @@ pub fn init_array_from_fn<I, const N: usize, T, E>(
 ///
 /// ```rust
 /// use kernel::{sync::{Arc, Mutex}, init::pin_init_array_from_fn, new_mutex};
-/// let array: Arc<[Mutex<usize>; 1_000]>=
+/// let array: Arc<[Mutex<usize>; 1_000]> =
 ///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i))).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
@@ -1071,7 +1071,7 @@ pub fn pin_init_array_from_fn<I, const N: usize, T, E>(
         // Counts the number of initialized elements and when dropped drops that many elements from
         // `slot`.
         let mut init_count = ScopeGuard::new_with_data(0, |i| {
-            // We now free every element that has been initialized before:
+            // We now free every element that has been initialized before.
             // SAFETY: The loop initialized exactly the values from 0..i and since we
             // return `Err` below, the caller will consider the memory at `slot` as
             // uninitialized.
diff --git a/rust/kernel/ioctl.rs b/rust/kernel/ioctl.rs
index f1d42ab69972..59050e5f5a5a 100644
--- a/rust/kernel/ioctl.rs
+++ b/rust/kernel/ioctl.rs
@@ -28,13 +28,13 @@ pub const fn _IO(ty: u32, nr: u32) -> u32 {
     _IOC(uapi::_IOC_NONE, ty, nr, 0)
 }
 
-/// Build an ioctl number for an read-only ioctl.
+/// Build an ioctl number for a read-only ioctl.
 #[inline(always)]
 pub const fn _IOR<T>(ty: u32, nr: u32) -> u32 {
     _IOC(uapi::_IOC_READ, ty, nr, core::mem::size_of::<T>())
 }
 
-/// Build an ioctl number for an write-only ioctl.
+/// Build an ioctl number for a write-only ioctl.
 #[inline(always)]
 pub const fn _IOW<T>(ty: u32, nr: u32) -> u32 {
     _IOC(uapi::_IOC_WRITE, ty, nr, core::mem::size_of::<T>())
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 7d848b83add4..0a8569594fc3 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -449,7 +449,7 @@ pub(crate) fn pos(&self) -> *mut u8 {
         self.pos as _
     }
 
-    /// Return the number of bytes written to the formatter.
+    /// Returns the number of bytes written to the formatter.
     pub(crate) fn bytes_written(&self) -> usize {
         self.pos - self.beg
     }
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index 149a5259d431..072b8ef2a0fa 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -21,9 +21,9 @@
 /// # Safety
 ///
 /// - Implementers must ensure that only one thread/CPU may access the protected data once the lock
-/// is owned, that is, between calls to `lock` and `unlock`.
+///   is owned, that is, between calls to `lock` and `unlock`.
 /// - Implementers must also ensure that `relock` uses the same locking method as the original
-/// lock operation.
+///   lock operation.
 pub unsafe trait Backend {
     /// The state required by the lock.
     type State;
diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs
index 068535ce1b29..e5e0bf621988 100644
--- a/rust/kernel/sync/lock/spinlock.rs
+++ b/rust/kernel/sync/lock/spinlock.rs
@@ -112,7 +112,7 @@ unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState {
 
     unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) {
         // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the
-        // caller is the owner of the mutex.
+        // caller is the owner of the spinlock.
         unsafe { bindings::spin_unlock(ptr) }
     }
 }
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 498397877376..8775c34d12a5 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -253,7 +253,7 @@ fn run(mut this: Pin<Box<Self>>) {
 /// actual value of the id is not important as long as you use different ids for different fields
 /// of the same struct. (Fields of different structs need not use different ids.)
 ///
-/// Note that the id is used only to select the right method to call during compilation. It wont be
+/// Note that the id is used only to select the right method to call during compilation. It won't be
 /// part of the final executable.
 ///
 /// # Safety

-- 
2.43.0

[PATCH v3 02/12] rust: error: improve unsafe code in example

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

The `from_err_ptr` function is safe. There is no need for the call to it
to be inside the unsafe block.

Reword the SAFETY comment to provide a better justification of why the
FFI call is safe.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/error.rs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 4f0c1edd63b7..4786d3ee1e92 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -264,13 +264,9 @@ pub fn to_result(err: core::ffi::c_int) -> Result {
 ///     pdev: &mut PlatformDevice,
 ///     index: u32,
 /// ) -> Result<*mut core::ffi::c_void> {
-///     // SAFETY: FFI call.
-///     unsafe {
-///         from_err_ptr(bindings::devm_platform_ioremap_resource(
-///             pdev.to_ptr(),
-///             index,
-///         ))
-///     }
+///     // SAFETY: `pdev` points to a valid platform device. There are no safety requirements
+///     // on `index`.
+///     from_err_ptr(unsafe { bindings::devm_platform_ioremap_resource(pdev.to_ptr(), index) })
 /// }
 /// ```
 // TODO: Remove `dead_code` marker once an in-kernel client is available.

-- 
2.43.0

[PATCH v3 03/12] rust: ioctl: end top-level module docs with full stop

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Every other module ends its first line of documentation with a full
stop. Adapt the only outlier.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/ioctl.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/ioctl.rs b/rust/kernel/ioctl.rs
index 59050e5f5a5a..5987ad6d38a7 100644
--- a/rust/kernel/ioctl.rs
+++ b/rust/kernel/ioctl.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-//! ioctl() number definitions
+//! ioctl() number definitions.
 //!
 //! C header: [`include/asm-generic/ioctl.h`](srctree/include/asm-generic/ioctl.h)
 

-- 
2.43.0

[PATCH v3 04/12] rust: kernel: add srctree-relative doclinks

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Convert existing references to C header files to make use of
Commit bc2e7d5c298a ("rust: support `srctree`-relative links").

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/lib.rs          | 2 +-
 rust/kernel/sync/condvar.rs | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b89ecf4e97a0..74581c958a6c 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -78,7 +78,7 @@ pub trait Module: Sized + Sync {
 
 /// Equivalent to `THIS_MODULE` in the C API.
 ///
-/// C header: `include/linux/export.h`
+/// C header: [`include/linux/export.h`](srctree/include/linux/export.h)
 pub struct ThisModule(*mut bindings::module);
 
 // SAFETY: `THIS_MODULE` may be used from all threads within a module.
diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index 9f1d83589beb..fa1794972aa0 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -87,6 +87,8 @@ pub struct CondVar {
 
     /// A condvar needs to be pinned because it contains a [`struct list_head`] that is
     /// self-referential, so it cannot be safely moved once it is initialised.
+    ///
+    /// [`struct list_head`]: srctree/include/linux/types.h
     #[pin]
     _pin: PhantomPinned,
 }

-- 
2.43.0

[PATCH v3 05/12] rust: str: use `NUL` instead of 0 in doc comments

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Throughout the module, bytes with the value zero are referred to as
`NUL` bytes. Adapt the only two outliers.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/str.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 0a8569594fc3..843ffeec9b3e 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -149,13 +149,13 @@ pub const fn as_char_ptr(&self) -> *const core::ffi::c_char {
         self.0.as_ptr() as _
     }
 
-    /// Convert the string to a byte slice without the trailing 0 byte.
+    /// Convert the string to a byte slice without the trailing `NUL` byte.
     #[inline]
     pub fn as_bytes(&self) -> &[u8] {
         &self.0[..self.len()]
     }
 
-    /// Convert the string to a byte slice containing the trailing 0 byte.
+    /// Convert the string to a byte slice containing the trailing `NUL` byte.
     #[inline]
     pub const fn as_bytes_with_nul(&self) -> &[u8] {
         &self.0

-- 
2.43.0

[PATCH v3 06/12] rust: str: move SAFETY comment in front of unsafe block

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

SAFETY comments should immediately precede the unsafe block they
justify. Move assignment to `bar` past comment as it is safe.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/str.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 843ffeec9b3e..fec5c4314758 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -191,9 +191,9 @@ pub fn to_str(&self) -> Result<&str, core::str::Utf8Error> {
     /// ```
     /// # use kernel::c_str;
     /// # use kernel::str::CStr;
+    /// let bar = c_str!("ツ");
     /// // SAFETY: String literals are guaranteed to be valid UTF-8
     /// // by the Rust compiler.
-    /// let bar = c_str!("ツ");
     /// assert_eq!(unsafe { bar.as_str_unchecked() }, "ツ");
     /// ```
     #[inline]

-- 
2.43.0

[PATCH v3 07/12] rust: kernel: unify spelling of refcount in docs

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Replace instances of 'ref-count[ed]' with 'refcount[ed]' to increase
consistency within the Rust documentation. The latter form is used more
widely in the rest of the kernel:

```console
$ rg '(\*|//).*?\srefcount(|ed)[\s,.]' | wc -l
1605
$ rg '(\*|//).*?\sref-count(|ed)[\s,.]' | wc -l
43
```

(numbers are for Commit 052d534373b7)

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/sync/arc.rs | 8 ++++----
 rust/kernel/task.rs     | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 77cdbcf7bd2e..6c46b1affca5 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -56,7 +56,7 @@
 ///     b: u32,
 /// }
 ///
-/// // Create a ref-counted instance of `Example`.
+/// // Create a refcounted instance of `Example`.
 /// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
 ///
 /// // Get a new pointer to `obj` and increment the refcount.
@@ -510,7 +510,7 @@ fn deref(&self) -> &Self::Target {
 /// # test().unwrap();
 /// ```
 ///
-/// In the following example we first allocate memory for a ref-counted `Example` but we don't
+/// In the following example we first allocate memory for a refcounted `Example` but we don't
 /// initialise it on allocation. We do initialise it later with a call to [`UniqueArc::write`],
 /// followed by a conversion to `Arc<Example>`. This is particularly useful when allocation happens
 /// in one context (e.g., sleepable) and initialisation in another (e.g., atomic):
@@ -560,7 +560,7 @@ impl<T> UniqueArc<T> {
     /// Tries to allocate a new [`UniqueArc`] instance.
     pub fn try_new(value: T) -> Result<Self, AllocError> {
         Ok(Self {
-            // INVARIANT: The newly-created object has a ref-count of 1.
+            // INVARIANT: The newly-created object has a refcount of 1.
             inner: Arc::try_new(value)?,
         })
     }
@@ -574,7 +574,7 @@ pub fn try_new_uninit() -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
             data <- init::uninit::<T, AllocError>(),
         }? AllocError))?;
         Ok(UniqueArc {
-            // INVARIANT: The newly-created object has a ref-count of 1.
+            // INVARIANT: The newly-created object has a refcount of 1.
             // SAFETY: The pointer from the `Box` is valid.
             inner: unsafe { Arc::from_inner(Box::leak(inner).into()) },
         })
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index a3a4007db682..6726f1056066 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -39,7 +39,7 @@ macro_rules! current {
 ///
 /// All instances are valid tasks created by the C portion of the kernel.
 ///
-/// Instances of this type are always ref-counted, that is, a call to `get_task_struct` ensures
+/// Instances of this type are always refcounted, that is, a call to `get_task_struct` ensures
 /// that the allocation remains valid at least until the matching call to `put_task_struct`.
 ///
 /// # Examples
@@ -163,7 +163,7 @@ pub fn wake_up(&self) {
     }
 }
 
-// SAFETY: The type invariants guarantee that `Task` is always ref-counted.
+// SAFETY: The type invariants guarantee that `Task` is always refcounted.
 unsafe impl crate::types::AlwaysRefCounted for Task {
     fn inc_ref(&self) {
         // SAFETY: The existence of a shared reference means that the refcount is nonzero.

-- 
2.43.0

[PATCH v3 08/12] rust: kernel: mark code fragments in docs with backticks

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Fix places where comments include code fragments that are not enclosed
in backticks.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/ioctl.rs     | 2 +-
 rust/kernel/sync/lock.rs | 2 +-
 rust/kernel/task.rs      | 2 +-
 rust/kernel/workqueue.rs | 9 +++++----
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/rust/kernel/ioctl.rs b/rust/kernel/ioctl.rs
index 5987ad6d38a7..cfa7d080b531 100644
--- a/rust/kernel/ioctl.rs
+++ b/rust/kernel/ioctl.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-//! ioctl() number definitions.
+//! `ioctl()` number definitions.
 //!
 //! C header: [`include/asm-generic/ioctl.h`](srctree/include/asm-generic/ioctl.h)
 
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index 072b8ef2a0fa..10ccc0e39147 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -28,7 +28,7 @@ pub unsafe trait Backend {
     /// The state required by the lock.
     type State;
 
-    /// The state required to be kept between lock and unlock.
+    /// The state required to be kept between `lock` and `unlock`.
     type GuardState;
 
     /// Initialises the lock.
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 6726f1056066..ca6e7e31d71c 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -132,7 +132,7 @@ fn deref(&self) -> &Self::Target {
     /// Returns the group leader of the given task.
     pub fn group_leader(&self) -> &Task {
         // SAFETY: By the type invariant, we know that `self.0` is a valid task. Valid tasks always
-        // have a valid group_leader.
+        // have a valid `group_leader`.
         let ptr = unsafe { *ptr::addr_of!((*self.0.get()).group_leader) };
 
         // SAFETY: The lifetime of the returned task reference is tied to the lifetime of `self`,
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 8775c34d12a5..d900dc911149 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -168,7 +168,7 @@ impl Queue {
     /// # Safety
     ///
     /// The caller must ensure that the provided raw pointer is not dangling, that it points at a
-    /// valid workqueue, and that it remains valid until the end of 'a.
+    /// valid workqueue, and that it remains valid until the end of `'a`.
     pub unsafe fn from_raw<'a>(ptr: *const bindings::workqueue_struct) -> &'a Queue {
         // SAFETY: The `Queue` type is `#[repr(transparent)]`, so the pointer cast is valid. The
         // caller promises that the pointer is not dangling.
@@ -414,8 +414,8 @@ pub unsafe fn raw_get(ptr: *const Self) -> *mut bindings::work_struct {
 ///
 /// # Safety
 ///
-/// The [`OFFSET`] constant must be the offset of a field in Self of type [`Work<T, ID>`]. The methods on
-/// this trait must have exactly the behavior that the definitions given below have.
+/// The [`OFFSET`] constant must be the offset of a field in `Self` of type [`Work<T, ID>`]. The
+/// methods on this trait must have exactly the behavior that the definitions given below have.
 ///
 /// [`Work<T, ID>`]: Work
 /// [`impl_has_work!`]: crate::impl_has_work
@@ -428,7 +428,8 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
 
     /// Returns the offset of the [`Work<T, ID>`] field.
     ///
-    /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not Sized.
+    /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not
+    /// `Sized`.
     ///
     /// [`Work<T, ID>`]: Work
     /// [`OFFSET`]: HasWork::OFFSET

-- 
2.43.0

[PATCH v3 09/12] rust: kernel: add blank lines in front of code blocks

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Throughout the code base, blank lines are used before starting a code
block. Adapt outliers to improve consistency within the kernel crate.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/types.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index fdb778e65d79..8aabe348b194 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -90,6 +90,7 @@ unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
 ///
 /// In the example below, we have multiple exit paths and we want to log regardless of which one is
 /// taken:
+///
 /// ```
 /// # use kernel::types::ScopeGuard;
 /// fn example1(arg: bool) {
@@ -108,6 +109,7 @@ unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
 ///
 /// In the example below, we want to log the same message on all early exits but a different one on
 /// the main exit path:
+///
 /// ```
 /// # use kernel::types::ScopeGuard;
 /// fn example2(arg: bool) {
@@ -129,6 +131,7 @@ unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
 ///
 /// In the example below, we need a mutable object (the vector) to be accessible within the log
 /// function, so we wrap it in the [`ScopeGuard`]:
+///
 /// ```
 /// # use kernel::types::ScopeGuard;
 /// fn example3(arg: bool) -> Result {

-- 
2.43.0

[PATCH v3 10/12] rust: kernel: add doclinks

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Add doclinks to existing documentation.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/sync/arc.rs  |  6 +++---
 rust/kernel/sync/lock.rs | 13 ++++++++++---
 rust/kernel/workqueue.rs | 45 +++++++++++++++++++++++++++------------------
 3 files changed, 40 insertions(+), 24 deletions(-)

diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 6c46b1affca5..936bc549a082 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -365,12 +365,12 @@ fn from(item: Pin<UniqueArc<T>>) -> Self {
 /// A borrowed reference to an [`Arc`] instance.
 ///
 /// For cases when one doesn't ever need to increment the refcount on the allocation, it is simpler
-/// to use just `&T`, which we can trivially get from an `Arc<T>` instance.
+/// to use just `&T`, which we can trivially get from an [`Arc<T>`] instance.
 ///
 /// However, when one may need to increment the refcount, it is preferable to use an `ArcBorrow<T>`
 /// over `&Arc<T>` because the latter results in a double-indirection: a pointer (shared reference)
-/// to a pointer (`Arc<T>`) to the object (`T`). An [`ArcBorrow`] eliminates this double
-/// indirection while still allowing one to increment the refcount and getting an `Arc<T>` when/if
+/// to a pointer ([`Arc<T>`]) to the object (`T`). An [`ArcBorrow`] eliminates this double
+/// indirection while still allowing one to increment the refcount and getting an [`Arc<T>`] when/if
 /// needed.
 ///
 /// # Invariants
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index 10ccc0e39147..5b5c8efe427a 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -21,14 +21,21 @@
 /// # Safety
 ///
 /// - Implementers must ensure that only one thread/CPU may access the protected data once the lock
-///   is owned, that is, between calls to `lock` and `unlock`.
-/// - Implementers must also ensure that `relock` uses the same locking method as the original
+///   is owned, that is, between calls to [`lock`] and [`unlock`].
+/// - Implementers must also ensure that [`relock`] uses the same locking method as the original
 ///   lock operation.
+///
+/// [`lock`]: Backend::lock
+/// [`unlock`]: Backend::unlock
+/// [`relock`]: Backend::relock
 pub unsafe trait Backend {
     /// The state required by the lock.
     type State;
 
-    /// The state required to be kept between `lock` and `unlock`.
+    /// The state required to be kept between [`lock`] and [`unlock`].
+    ///
+    /// [`lock`]: Backend::lock
+    /// [`unlock`]: Backend::unlock
     type GuardState;
 
     /// Initialises the lock.
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index d900dc911149..ed3af3491b47 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -12,19 +12,19 @@
 //!
 //! # The raw API
 //!
-//! The raw API consists of the `RawWorkItem` trait, where the work item needs to provide an
+//! The raw API consists of the [`RawWorkItem`] trait, where the work item needs to provide an
 //! arbitrary function that knows how to enqueue the work item. It should usually not be used
 //! directly, but if you want to, you can use it without using the pieces from the safe API.
 //!
 //! # The safe API
 //!
-//! The safe API is used via the `Work` struct and `WorkItem` traits. Furthermore, it also includes
-//! a trait called `WorkItemPointer`, which is usually not used directly by the user.
+//! The safe API is used via the [`Work`] struct and [`WorkItem`] traits. Furthermore, it also
+//! includes a trait called [`WorkItemPointer`], which is usually not used directly by the user.
 //!
-//!  * The `Work` struct is the Rust wrapper for the C `work_struct` type.
-//!  * The `WorkItem` trait is implemented for structs that can be enqueued to a workqueue.
-//!  * The `WorkItemPointer` trait is implemented for the pointer type that points at a something
-//!    that implements `WorkItem`.
+//!  * The [`Work`] struct is the Rust wrapper for the C `work_struct` type.
+//!  * The [`WorkItem`] trait is implemented for structs that can be enqueued to a workqueue.
+//!  * The [`WorkItemPointer`] trait is implemented for the pointer type that points at a something
+//!    that implements [`WorkItem`].
 //!
 //! ## Example
 //!
@@ -218,7 +218,9 @@ pub fn try_spawn<T: 'static + Send + FnOnce()>(&self, func: T) -> Result<(), All
     }
 }
 
-/// A helper type used in `try_spawn`.
+/// A helper type used in [`try_spawn`].
+///
+/// [`try_spawn`]: Queue::try_spawn
 #[pin_data]
 struct ClosureWork<T> {
     #[pin]
@@ -258,9 +260,11 @@ fn run(mut this: Pin<Box<Self>>) {
 ///
 /// # Safety
 ///
-/// Implementers must ensure that any pointers passed to a `queue_work_on` closure by `__enqueue`
+/// Implementers must ensure that any pointers passed to a `queue_work_on` closure by [`__enqueue`]
 /// remain valid for the duration specified in the guarantees section of the documentation for
-/// `__enqueue`.
+/// [`__enqueue`].
+///
+/// [`__enqueue`]: RawWorkItem::__enqueue
 pub unsafe trait RawWorkItem<const ID: u64> {
     /// The return type of [`Queue::enqueue`].
     type EnqueueOutput;
@@ -290,10 +294,11 @@ unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
 
 /// Defines the method that should be called directly when a work item is executed.
 ///
-/// This trait is implemented by `Pin<Box<T>>` and `Arc<T>`, and is mainly intended to be
+/// This trait is implemented by `Pin<Box<T>>` and [`Arc<T>`], and is mainly intended to be
 /// implemented for smart pointer types. For your own structs, you would implement [`WorkItem`]
-/// instead. The `run` method on this trait will usually just perform the appropriate
-/// `container_of` translation and then call into the `run` method from the [`WorkItem`] trait.
+/// instead. The [`run`] method on this trait will usually just perform the appropriate
+/// `container_of` translation and then call into the [`run`][WorkItem::run] method from the
+/// [`WorkItem`] trait.
 ///
 /// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
 ///
@@ -309,8 +314,10 @@ pub unsafe trait WorkItemPointer<const ID: u64>: RawWorkItem<ID> {
     ///
     /// # Safety
     ///
-    /// The provided `work_struct` pointer must originate from a previous call to `__enqueue` where
-    /// the `queue_work_on` closure returned true, and the pointer must still be valid.
+    /// The provided `work_struct` pointer must originate from a previous call to [`__enqueue`]
+    /// where the `queue_work_on` closure returned true, and the pointer must still be valid.
+    ///
+    /// [`__enqueue`]: RawWorkItem::__enqueue
     unsafe extern "C" fn run(ptr: *mut bindings::work_struct);
 }
 
@@ -328,12 +335,14 @@ pub trait WorkItem<const ID: u64 = 0> {
 
 /// Links for a work item.
 ///
-/// This struct contains a function pointer to the `run` function from the [`WorkItemPointer`]
+/// This struct contains a function pointer to the [`run`] function from the [`WorkItemPointer`]
 /// trait, and defines the linked list pointers necessary to enqueue a work item in a workqueue.
 ///
 /// Wraps the kernel's C `struct work_struct`.
 ///
 /// This is a helper type used to associate a `work_struct` with the [`WorkItem`] that uses it.
+///
+/// [`run`]: WorkItemPointer::run
 #[repr(transparent)]
 pub struct Work<T: ?Sized, const ID: u64 = 0> {
     work: Opaque<bindings::work_struct>,
@@ -409,7 +418,7 @@ pub unsafe fn raw_get(ptr: *const Self) -> *mut bindings::work_struct {
 /// }
 /// ```
 ///
-/// Note that since the `Work` type is annotated with an id, you can have several `work_struct`
+/// Note that since the [`Work`] type is annotated with an id, you can have several `work_struct`
 /// fields by using a different id for each one.
 ///
 /// # Safety
@@ -429,7 +438,7 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
     /// Returns the offset of the [`Work<T, ID>`] field.
     ///
     /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not
-    /// `Sized`.
+    /// [`Sized`].
     ///
     /// [`Work<T, ID>`]: Work
     /// [`OFFSET`]: HasWork::OFFSET

-- 
2.43.0

[PATCH v3 11/12] rust: kernel: remove unneeded doclink targets

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Remove explicit targets for doclinks in cases where rustdoc can
determine the correct target by itself. The goal is to reduce unneeded
verbosity in the source code.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/workqueue.rs | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index ed3af3491b47..73d6fa544ca6 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -426,13 +426,10 @@ pub unsafe fn raw_get(ptr: *const Self) -> *mut bindings::work_struct {
 /// The [`OFFSET`] constant must be the offset of a field in `Self` of type [`Work<T, ID>`]. The
 /// methods on this trait must have exactly the behavior that the definitions given below have.
 ///
-/// [`Work<T, ID>`]: Work
 /// [`impl_has_work!`]: crate::impl_has_work
 /// [`OFFSET`]: HasWork::OFFSET
 pub unsafe trait HasWork<T, const ID: u64 = 0> {
     /// The offset of the [`Work<T, ID>`] field.
-    ///
-    /// [`Work<T, ID>`]: Work
     const OFFSET: usize;
 
     /// Returns the offset of the [`Work<T, ID>`] field.
@@ -440,7 +437,6 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
     /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not
     /// [`Sized`].
     ///
-    /// [`Work<T, ID>`]: Work
     /// [`OFFSET`]: HasWork::OFFSET
     #[inline]
     fn get_work_offset(&self) -> usize {
@@ -452,8 +448,6 @@ fn get_work_offset(&self) -> usize {
     /// # Safety
     ///
     /// The provided pointer must point at a valid struct of type `Self`.
-    ///
-    /// [`Work<T, ID>`]: Work
     #[inline]
     unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work<T, ID> {
         // SAFETY: The caller promises that the pointer is valid.
@@ -465,8 +459,6 @@ unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work<T, ID> {
     /// # Safety
     ///
     /// The pointer must point at a [`Work<T, ID>`] field in a struct of type `Self`.
-    ///
-    /// [`Work<T, ID>`]: Work
     #[inline]
     unsafe fn work_container_of(ptr: *mut Work<T, ID>) -> *mut Self
     where
@@ -495,8 +487,6 @@ unsafe fn work_container_of(ptr: *mut Work<T, ID>) -> *mut Self
 ///     impl HasWork<MyStruct, 17> for MyStruct { self.work_field }
 /// }
 /// ```
-///
-/// [`HasWork<T, ID>`]: HasWork
 #[macro_export]
 macro_rules! impl_has_work {
     ($(impl$(<$($implarg:ident),*>)?

-- 
2.43.0

[PATCH v3 12/12] rust: locked_by: shorten doclink preview

[Valentin Obst via B4 Relay]

From: Valentin Obst <kernel@valentinobst.de>

Increases readability by removing `super::` from the link preview
text.

Signed-off-by: Valentin Obst <kernel@valentinobst.de>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/sync/locked_by.rs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/sync/locked_by.rs b/rust/kernel/sync/locked_by.rs
index b17ee5cd98f3..babc731bd5f6 100644
--- a/rust/kernel/sync/locked_by.rs
+++ b/rust/kernel/sync/locked_by.rs
@@ -9,14 +9,17 @@
 /// Allows access to some data to be serialised by a lock that does not wrap it.
 ///
 /// In most cases, data protected by a lock is wrapped by the appropriate lock type, e.g.,
-/// [`super::Mutex`] or [`super::SpinLock`]. [`LockedBy`] is meant for cases when this is not
-/// possible. For example, if a container has a lock and some data in the contained elements needs
+/// [`Mutex`] or [`SpinLock`]. [`LockedBy`] is meant for cases when this is not possible.
+/// For example, if a container has a lock and some data in the contained elements needs
 /// to be protected by the same lock.
 ///
 /// [`LockedBy`] wraps the data in lieu of another locking primitive, and only allows access to it
 /// when the caller shows evidence that the 'external' lock is locked. It panics if the evidence
 /// refers to the wrong instance of the lock.
 ///
+/// [`Mutex`]: super::Mutex
+/// [`SpinLock`]: super::SpinLock
+///
 /// # Examples
 ///
 /// The following is an example for illustrative purposes: `InnerDirectory::bytes_used` is an

-- 
2.43.0

Re: [PATCH v3 02/12] rust: error: improve unsafe code in example

[Trevor Gross]

On Wed, Jan 31, 2024 at 3:24 PM Valentin Obst via B4 Relay
<devnull+kernel.valentinobst.de@kernel.org> wrote:
>
> From: Valentin Obst <kernel@valentinobst.de>
>
> The `from_err_ptr` function is safe. There is no need for the call to it
> to be inside the unsafe block.
>
> Reword the SAFETY comment to provide a better justification of why the
> FFI call is safe.
>
> Signed-off-by: Valentin Obst <kernel@valentinobst.de>
> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>

Reviewed-by: Trevor Gross <tmgross@umich.edu>

> ---
>  rust/kernel/error.rs | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 4f0c1edd63b7..4786d3ee1e92 100644
> --- a/rust/kernel/error.rs
> +++ b/rust/kernel/error.rs
> @@ -264,13 +264,9 @@ pub fn to_result(err: core::ffi::c_int) -> Result {
>  ///     pdev: &mut PlatformDevice,
>  ///     index: u32,
>  /// ) -> Result<*mut core::ffi::c_void> {
> -///     // SAFETY: FFI call.
> -///     unsafe {
> -///         from_err_ptr(bindings::devm_platform_ioremap_resource(
> -///             pdev.to_ptr(),
> -///             index,
> -///         ))
> -///     }
> +///     // SAFETY: `pdev` points to a valid platform device. There are no safety requirements
> +///     // on `index`.
> +///     from_err_ptr(unsafe { bindings::devm_platform_ioremap_resource(pdev.to_ptr(), index) })
>  /// }
>  /// ```
>  // TODO: Remove `dead_code` marker once an in-kernel client is available.
>
> --
> 2.43.0
>
>

Re: [PATCH v3 00/12] rust: kernel: documentation improvements

[Miguel Ojeda]

On Wed, Jan 31, 2024 at 9:24 PM Valentin Obst via B4 Relay
<devnull+kernel.valentinobst.de@kernel.org> wrote:
>
> This patch set aims to make small improvements to the documentation of
> the kernel crate. It engages in a few different activities:
> - fixing trivial typos (commit #1),
> - updating code examples to better reflect an idiomatic coding style
>   (commits #2,6),
> - increasing the consistency within the crate's documentation as a whole
>   (commits #3,5,7,8,9,11,12),
> - adding more intra-doc links as well as srctree-relative links to C
>   header files (commits #4,10).

Applied to `rust-next` with a small reword in one of the commits to
use the kernel's commit description style -- thanks everyone!

Cheers,
Miguel