Merge tag 'rust-6.9' of https://github.com/Rust-for-Linux/linux

Pull Rust updates from Miguel Ojeda:
 "Another routine one in terms of features. We got two version upgrades
  this time, but in terms of lines, 'alloc' changes are not very large.

  Toolchain and infrastructure:

   - Upgrade to Rust 1.76.0

     This time around, due to how the kernel and Rust schedules have
     aligned, there are two upgrades in fact. These allow us to remove
     two more unstable features ('const_maybe_uninit_zeroed' and
     'ptr_metadata') from the list, among other improvements

   - Mark 'rustc' (and others) invocations as recursive, which fixes a
     new warning and prepares us for the future in case we eventually
     take advantage of the Make jobserver

  'kernel' crate:

   - Add the 'container_of!' macro

   - Stop using the unstable 'ptr_metadata' feature by employing the now
     stable 'byte_sub' method to implement 'Arc::from_raw()'

   - Add the 'time' module with a 'msecs_to_jiffies()' conversion
     function to begin with, to be used by Rust Binder

   - Add 'notify_sync()' and 'wait_interruptible_timeout()' methods to
     'CondVar', to be used by Rust Binder

   - Update integer types for 'CondVar'

   - Rename 'wait_list' field to 'wait_queue_head' in 'CondVar'

   - Implement 'Display' and 'Debug' for 'BStr'

   - Add the 'try_from_foreign()' method to the 'ForeignOwnable' trait

   - Add reexports for macros so that they can be used from the right
     module (in addition to the root)

   - A series of code documentation improvements, including adding
     intra-doc links, consistency improvements, typo fixes...

  'macros' crate:

   - Place generated 'init_module()' function in '.init.text'

  Documentation:

   - Add documentation on Rust doctests and how they work"

* tag 'rust-6.9' of https://github.com/Rust-for-Linux/linux: (29 commits)
  rust: upgrade to Rust 1.76.0
  kbuild: mark `rustc` (and others) invocations as recursive
  rust: add `container_of!` macro
  rust: str: implement `Display` and `Debug` for `BStr`
  rust: module: place generated init_module() function in .init.text
  rust: types: add `try_from_foreign()` method
  docs: rust: Add description of Rust documentation test as KUnit ones
  docs: rust: Move testing to a separate page
  rust: kernel: stop using ptr_metadata feature
  rust: kernel: add reexports for macros
  rust: locked_by: shorten doclink preview
  rust: kernel: remove unneeded doclink targets
  rust: kernel: add doclinks
  rust: kernel: add blank lines in front of code blocks
  rust: kernel: mark code fragments in docs with backticks
  rust: kernel: unify spelling of refcount in docs
  rust: str: move SAFETY comment in front of unsafe block
  rust: str: use `NUL` instead of 0 in doc comments
  rust: kernel: add srctree-relative doclinks
  rust: ioctl: end top-level module docs with full stop
  ...

17 files changed, 462 insertions, 131 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/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.
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 65be9ae57b80..424257284d16 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -36,7 +36,7 @@
 //!
 //! ```rust
 //! # #![allow(clippy::disallowed_names)]
-//! use kernel::{prelude::*, sync::Mutex, new_mutex};
+//! use kernel::sync::{new_mutex, Mutex};
 //! # use core::pin::Pin;
 //! #[pin_data]
 //! struct Foo {
@@ -56,7 +56,7 @@
 //!
 //! ```rust
 //! # #![allow(clippy::disallowed_names)]
-//! # use kernel::{prelude::*, sync::Mutex, new_mutex};
+//! # use kernel::sync::{new_mutex, Mutex};
 //! # use core::pin::Pin;
 //! # #[pin_data]
 //! # struct Foo {
@@ -79,7 +79,7 @@
 //! above method only works for types where you can access the fields.
 //!
 //! ```rust
-//! # use kernel::{new_mutex, sync::{Arc, Mutex}};
+//! # use kernel::sync::{new_mutex, Arc, Mutex};
 //! let mtx: Result<Arc<Mutex<usize>>> = Arc::pin_init(new_mutex!(42, "example::mtx"));
 //! ```
 //!
@@ -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 @@ where
 ///
 /// # 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 @@ where
         // 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 @@ where
 ///
 /// ```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 @@ where
         // 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..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)
 
@@ -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/lib.rs b/rust/kernel/lib.rs
index 7ac39874aeac..be68d5e567b1 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -14,11 +14,9 @@
 #![no_std]
 #![feature(allocator_api)]
 #![feature(coerce_unsized)]
-#![feature(const_maybe_uninit_zeroed)]
 #![feature(dispatch_from_dyn)]
 #![feature(new_uninit)]
 #![feature(offset_of)]
-#![feature(ptr_metadata)]
 #![feature(receiver_trait)]
 #![feature(unsize)]
 
@@ -49,6 +47,7 @@ pub mod std_vendor;
 pub mod str;
 pub mod sync;
 pub mod task;
+pub mod time;
 pub mod types;
 pub mod workqueue;
 
@@ -78,7 +77,7 @@ 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.
@@ -102,3 +101,35 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
     // SAFETY: FFI call.
     unsafe { bindings::BUG() };
 }
+
+/// Produces a pointer to an object from a pointer to one of its fields.
+///
+/// # Safety
+///
+/// The pointer passed to this macro, and the pointer returned by this macro, must both be in
+/// bounds of the same allocation.
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::container_of;
+/// struct Test {
+///     a: u64,
+///     b: u32,
+/// }
+///
+/// let test = Test { a: 10, b: 20 };
+/// let b_ptr = &test.b;
+/// // SAFETY: The pointer points at the `b` field of a `Test`, so the resulting pointer will be
+/// // in-bounds of the same allocation as `b_ptr`.
+/// let test_alias = unsafe { container_of!(b_ptr, Test, b) };
+/// assert!(core::ptr::eq(&test, test_alias));
+/// ```
+#[macro_export]
+macro_rules! container_of {
+    ($ptr:expr, $type:ty, $($f:tt)*) => {{
+        let ptr = $ptr as *const _ as *const u8;
+        let offset: usize = ::core::mem::offset_of!($type, $($f)*);
+        ptr.sub(offset) as *const $type
+    }}
+}
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 7d848b83add4..925ced8fdc61 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -13,9 +13,102 @@ use crate::{
 };
 
 /// Byte string without UTF-8 validity guarantee.
-///
-/// `BStr` is simply an alias to `[u8]`, but has a more evident semantical meaning.
-pub type BStr = [u8];
+#[repr(transparent)]
+pub struct BStr([u8]);
+
+impl BStr {
+    /// Returns the length of this string.
+    #[inline]
+    pub const fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Returns `true` if the string is empty.
+    #[inline]
+    pub const fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Creates a [`BStr`] from a `[u8]`.
+    #[inline]
+    pub const fn from_bytes(bytes: &[u8]) -> &Self {
+        // SAFETY: `BStr` is transparent to `[u8]`.
+        unsafe { &*(bytes as *const [u8] as *const BStr) }
+    }
+}
+
+impl fmt::Display for BStr {
+    /// Formats printable ASCII characters, escaping the rest.
+    ///
+    /// ```
+    /// # use kernel::{fmt, b_str, str::{BStr, CString}};
+    /// let ascii = b_str!("Hello, BStr!");
+    /// let s = CString::try_from_fmt(fmt!("{}", ascii)).unwrap();
+    /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes());
+    ///
+    /// let non_ascii = b_str!("🦀");
+    /// let s = CString::try_from_fmt(fmt!("{}", non_ascii)).unwrap();
+    /// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes());
+    /// ```
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for &b in &self.0 {
+            match b {
+                // Common escape codes.
+                b'\t' => f.write_str("\\t")?,
+                b'\n' => f.write_str("\\n")?,
+                b'\r' => f.write_str("\\r")?,
+                // Printable characters.
+                0x20..=0x7e => f.write_char(b as char)?,
+                _ => write!(f, "\\x{:02x}", b)?,
+            }
+        }
+        Ok(())
+    }
+}
+
+impl fmt::Debug for BStr {
+    /// Formats printable ASCII characters with a double quote on either end,
+    /// escaping the rest.
+    ///
+    /// ```
+    /// # use kernel::{fmt, b_str, str::{BStr, CString}};
+    /// // Embedded double quotes are escaped.
+    /// let ascii = b_str!("Hello, \"BStr\"!");
+    /// let s = CString::try_from_fmt(fmt!("{:?}", ascii)).unwrap();
+    /// assert_eq!(s.as_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes());
+    ///
+    /// let non_ascii = b_str!("😺");
+    /// let s = CString::try_from_fmt(fmt!("{:?}", non_ascii)).unwrap();
+    /// assert_eq!(s.as_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes());
+    /// ```
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_char('"')?;
+        for &b in &self.0 {
+            match b {
+                // Common escape codes.
+                b'\t' => f.write_str("\\t")?,
+                b'\n' => f.write_str("\\n")?,
+                b'\r' => f.write_str("\\r")?,
+                // String escape characters.
+                b'\"' => f.write_str("\\\"")?,
+                b'\\' => f.write_str("\\\\")?,
+                // Printable characters.
+                0x20..=0x7e => f.write_char(b as char)?,
+                _ => write!(f, "\\x{:02x}", b)?,
+            }
+        }
+        f.write_char('"')
+    }
+}
+
+impl Deref for BStr {
+    type Target = [u8];
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
 
 /// Creates a new [`BStr`] from a string literal.
 ///
@@ -33,7 +126,7 @@ pub type BStr = [u8];
 macro_rules! b_str {
     ($str:literal) => {{
         const S: &'static str = $str;
-        const C: &'static $crate::str::BStr = S.as_bytes();
+        const C: &'static $crate::str::BStr = $crate::str::BStr::from_bytes(S.as_bytes());
         C
     }};
 }
@@ -149,13 +242,13 @@ impl CStr {
         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
@@ -191,9 +284,9 @@ impl CStr {
     /// ```
     /// # 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]
@@ -271,7 +364,7 @@ impl fmt::Debug for CStr {
 impl AsRef<BStr> for CStr {
     #[inline]
     fn as_ref(&self) -> &BStr {
-        self.as_bytes()
+        BStr::from_bytes(self.as_bytes())
     }
 }
 
@@ -280,7 +373,7 @@ impl Deref for CStr {
 
     #[inline]
     fn deref(&self) -> &Self::Target {
-        self.as_bytes()
+        self.as_ref()
     }
 }
 
@@ -327,7 +420,7 @@ where
 
     #[inline]
     fn index(&self, index: Idx) -> &Self::Output {
-        &self.as_bytes()[index]
+        &self.as_ref()[index]
     }
 }
 
@@ -357,6 +450,21 @@ macro_rules! c_str {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use alloc::format;
+
+    const ALL_ASCII_CHARS: &'static str =
+        "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\
+        \\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f \
+        !\"#$%&'()*+,-./0123456789:;<=>?@\
+        ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\\x7f\
+        \\x80\\x81\\x82\\x83\\x84\\x85\\x86\\x87\\x88\\x89\\x8a\\x8b\\x8c\\x8d\\x8e\\x8f\
+        \\x90\\x91\\x92\\x93\\x94\\x95\\x96\\x97\\x98\\x99\\x9a\\x9b\\x9c\\x9d\\x9e\\x9f\
+        \\xa0\\xa1\\xa2\\xa3\\xa4\\xa5\\xa6\\xa7\\xa8\\xa9\\xaa\\xab\\xac\\xad\\xae\\xaf\
+        \\xb0\\xb1\\xb2\\xb3\\xb4\\xb5\\xb6\\xb7\\xb8\\xb9\\xba\\xbb\\xbc\\xbd\\xbe\\xbf\
+        \\xc0\\xc1\\xc2\\xc3\\xc4\\xc5\\xc6\\xc7\\xc8\\xc9\\xca\\xcb\\xcc\\xcd\\xce\\xcf\
+        \\xd0\\xd1\\xd2\\xd3\\xd4\\xd5\\xd6\\xd7\\xd8\\xd9\\xda\\xdb\\xdc\\xdd\\xde\\xdf\
+        \\xe0\\xe1\\xe2\\xe3\\xe4\\xe5\\xe6\\xe7\\xe8\\xe9\\xea\\xeb\\xec\\xed\\xee\\xef\
+        \\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\xf7\\xf8\\xf9\\xfa\\xfb\\xfc\\xfd\\xfe\\xff";
 
     #[test]
     fn test_cstr_to_str() {
@@ -381,6 +489,69 @@ mod tests {
         let unchecked_str = unsafe { checked_cstr.as_str_unchecked() };
         assert_eq!(unchecked_str, "🐧");
     }
+
+    #[test]
+    fn test_cstr_display() {
+        let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap();
+        assert_eq!(format!("{}", hello_world), "hello, world!");
+        let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap();
+        assert_eq!(format!("{}", non_printables), "\\x01\\x09\\x0a");
+        let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap();
+        assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu");
+        let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap();
+        assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80");
+    }
+
+    #[test]
+    fn test_cstr_display_all_bytes() {
+        let mut bytes: [u8; 256] = [0; 256];
+        // fill `bytes` with [1..=255] + [0]
+        for i in u8::MIN..=u8::MAX {
+            bytes[i as usize] = i.wrapping_add(1);
+        }
+        let cstr = CStr::from_bytes_with_nul(&bytes).unwrap();
+        assert_eq!(format!("{}", cstr), ALL_ASCII_CHARS);
+    }
+
+    #[test]
+    fn test_cstr_debug() {
+        let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap();
+        assert_eq!(format!("{:?}", hello_world), "\"hello, world!\"");
+        let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap();
+        assert_eq!(format!("{:?}", non_printables), "\"\\x01\\x09\\x0a\"");
+        let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap();
+        assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\"");
+        let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap();
+        assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\"");
+    }
+
+    #[test]
+    fn test_bstr_display() {
+        let hello_world = BStr::from_bytes(b"hello, world!");
+        assert_eq!(format!("{}", hello_world), "hello, world!");
+        let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_");
+        assert_eq!(format!("{}", escapes), "_\\t_\\n_\\r_\\_'_\"_");
+        let others = BStr::from_bytes(b"\x01");
+        assert_eq!(format!("{}", others), "\\x01");
+        let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu");
+        assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu");
+        let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80");
+        assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80");
+    }
+
+    #[test]
+    fn test_bstr_debug() {
+        let hello_world = BStr::from_bytes(b"hello, world!");
+        assert_eq!(format!("{:?}", hello_world), "\"hello, world!\"");
+        let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_");
+        assert_eq!(format!("{:?}", escapes), "\"_\\t_\\n_\\r_\\\\_'_\\\"_\"");
+        let others = BStr::from_bytes(b"\x01");
+        assert_eq!(format!("{:?}", others), "\"\\x01\"");
+        let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu");
+        assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\"");
+        let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80");
+        assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\"");
+    }
 }
 
 /// Allows formatting of [`fmt::Arguments`] into a raw buffer.
@@ -449,7 +620,7 @@ impl RawFormatter {
         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.rs b/rust/kernel/sync.rs
index d219ee518eff..c983f63fd56e 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -13,8 +13,9 @@ pub mod lock;
 mod locked_by;
 
 pub use arc::{Arc, ArcBorrow, UniqueArc};
-pub use condvar::CondVar;
-pub use lock::{mutex::Mutex, spinlock::SpinLock};
+pub use condvar::{new_condvar, CondVar, CondVarTimeoutResult};
+pub use lock::mutex::{new_mutex, Mutex};
+pub use lock::spinlock::{new_spinlock, SpinLock};
 pub use locked_by::LockedBy;
 
 /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`.
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 77cdbcf7bd2e..7d4c4bf58388 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -30,7 +30,7 @@ use core::{
     mem::{ManuallyDrop, MaybeUninit},
     ops::{Deref, DerefMut},
     pin::Pin,
-    ptr::{NonNull, Pointee},
+    ptr::NonNull,
 };
 use macros::pin_data;
 
@@ -56,7 +56,7 @@ mod std_vendor;
 ///     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.
@@ -239,22 +239,20 @@ impl<T: ?Sized> Arc<T> {
         // binary, so its layout is not so large that it can trigger arithmetic overflow.
         let val_offset = unsafe { refcount_layout.extend(val_layout).unwrap_unchecked().1 };
 
-        let metadata: <T as Pointee>::Metadata = core::ptr::metadata(ptr);
-        // SAFETY: The metadata of `T` and `ArcInner<T>` is the same because `ArcInner` is a struct
-        // with `T` as its last field.
+        // Pointer casts leave the metadata unchanged. This is okay because the metadata of `T` and
+        // `ArcInner<T>` is the same since `ArcInner` is a struct with `T` as its last field.
         //
         // This is documented at:
         // <https://doc.rust-lang.org/std/ptr/trait.Pointee.html>.
-        let metadata: <ArcInner<T> as Pointee>::Metadata =
-            unsafe { core::mem::transmute_copy(&metadata) };
+        let ptr = ptr as *const ArcInner<T>;
+
         // SAFETY: The pointer is in-bounds of an allocation both before and after offsetting the
         // pointer, since it originates from a previous call to `Arc::into_raw` and is still valid.
-        let ptr = unsafe { (ptr as *mut u8).sub(val_offset) as *mut () };
-        let ptr = core::ptr::from_raw_parts_mut(ptr, metadata);
+        let ptr = unsafe { ptr.byte_sub(val_offset) };
 
         // SAFETY: By the safety requirements we know that `ptr` came from `Arc::into_raw`, so the
         // reference count held then will be owned by the new `Arc` object.
-        unsafe { Self::from_inner(NonNull::new_unchecked(ptr)) }
+        unsafe { Self::from_inner(NonNull::new_unchecked(ptr.cast_mut())) }
     }
 
     /// Returns an [`ArcBorrow`] from the given [`Arc`].
@@ -365,12 +363,12 @@ impl<T: ?Sized> From<Pin<UniqueArc<T>>> for Arc<T> {
 /// 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
@@ -510,7 +508,7 @@ impl<T: ?Sized> Deref for ArcBorrow<'_, T> {
 /// # 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 +558,7 @@ 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 +572,7 @@ impl<T> UniqueArc<T> {
             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/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index f65e19d5a37c..0c3671caffeb 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -6,8 +6,18 @@
 //! variable.
 
 use super::{lock::Backend, lock::Guard, LockClassKey};
-use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque};
+use crate::{
+    bindings,
+    init::PinInit,
+    pin_init,
+    str::CStr,
+    task::{MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE, TASK_NORMAL, TASK_UNINTERRUPTIBLE},
+    time::Jiffies,
+    types::Opaque,
+};
+use core::ffi::{c_int, c_long};
 use core::marker::PhantomPinned;
+use core::ptr;
 use macros::pin_data;
 
 /// Creates a [`CondVar`] initialiser with the given name and a newly-created lock class.
@@ -17,6 +27,7 @@ macro_rules! new_condvar {
         $crate::sync::CondVar::new($crate::optional_name!($($name)?), $crate::static_lock_class!())
     };
 }
+pub use new_condvar;
 
 /// A conditional variable.
 ///
@@ -34,8 +45,7 @@ macro_rules! new_condvar {
 /// The following is an example of using a condvar with a mutex:
 ///
 /// ```
-/// use kernel::sync::{CondVar, Mutex};
-/// use kernel::{new_condvar, new_mutex};
+/// use kernel::sync::{new_condvar, new_mutex, CondVar, Mutex};
 ///
 /// #[pin_data]
 /// pub struct Example {
@@ -73,10 +83,12 @@ macro_rules! new_condvar {
 #[pin_data]
 pub struct CondVar {
     #[pin]
-    pub(crate) wait_list: Opaque<bindings::wait_queue_head>,
+    pub(crate) wait_queue_head: Opaque<bindings::wait_queue_head>,
 
     /// 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,
 }
@@ -96,28 +108,35 @@ impl CondVar {
             _pin: PhantomPinned,
             // SAFETY: `slot` is valid while the closure is called and both `name` and `key` have
             // static lifetimes so they live indefinitely.
-            wait_list <- Opaque::ffi_init(|slot| unsafe {
+            wait_queue_head <- Opaque::ffi_init(|slot| unsafe {
                 bindings::__init_waitqueue_head(slot, name.as_char_ptr(), key.as_ptr())
             }),
         })
     }
 
-    fn wait_internal<T: ?Sized, B: Backend>(&self, wait_state: u32, guard: &mut Guard<'_, T, B>) {
+    fn wait_internal<T: ?Sized, B: Backend>(
+        &self,
+        wait_state: c_int,
+        guard: &mut Guard<'_, T, B>,
+        timeout_in_jiffies: c_long,
+    ) -> c_long {
         let wait = Opaque::<bindings::wait_queue_entry>::uninit();
 
         // SAFETY: `wait` points to valid memory.
         unsafe { bindings::init_wait(wait.get()) };
 
-        // SAFETY: Both `wait` and `wait_list` point to valid memory.
+        // SAFETY: Both `wait` and `wait_queue_head` point to valid memory.
         unsafe {
-            bindings::prepare_to_wait_exclusive(self.wait_list.get(), wait.get(), wait_state as _)
+            bindings::prepare_to_wait_exclusive(self.wait_queue_head.get(), wait.get(), wait_state)
         };
 
-        // SAFETY: No arguments, switches to another thread.
-        guard.do_unlocked(|| unsafe { bindings::schedule() });
+        // SAFETY: Switches to another thread. The timeout can be any number.
+        let ret = guard.do_unlocked(|| unsafe { bindings::schedule_timeout(timeout_in_jiffies) });
+
+        // SAFETY: Both `wait` and `wait_queue_head` point to valid memory.
+        unsafe { bindings::finish_wait(self.wait_queue_head.get(), wait.get()) };
 
-        // SAFETY: Both `wait` and `wait_list` point to valid memory.
-        unsafe { bindings::finish_wait(self.wait_list.get(), wait.get()) };
+        ret
     }
 
     /// Releases the lock and waits for a notification in uninterruptible mode.
@@ -127,7 +146,7 @@ impl CondVar {
     /// [`CondVar::notify_one`] or [`CondVar::notify_all`]. Note that it may also wake up
     /// spuriously.
     pub fn wait<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) {
-        self.wait_internal(bindings::TASK_UNINTERRUPTIBLE, guard);
+        self.wait_internal(TASK_UNINTERRUPTIBLE, guard, MAX_SCHEDULE_TIMEOUT);
     }
 
     /// Releases the lock and waits for a notification in interruptible mode.
@@ -138,29 +157,60 @@ impl CondVar {
     /// Returns whether there is a signal pending.
     #[must_use = "wait_interruptible returns if a signal is pending, so the caller must check the return value"]
     pub fn wait_interruptible<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) -> bool {
-        self.wait_internal(bindings::TASK_INTERRUPTIBLE, guard);
+        self.wait_internal(TASK_INTERRUPTIBLE, guard, MAX_SCHEDULE_TIMEOUT);
         crate::current!().signal_pending()
     }
 
-    /// Calls the kernel function to notify the appropriate number of threads with the given flags.
-    fn notify(&self, count: i32, flags: u32) {
-        // SAFETY: `wait_list` points to valid memory.
+    /// Releases the lock and waits for a notification in interruptible mode.
+    ///
+    /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the
+    /// thread to sleep. It wakes up when notified by [`CondVar::notify_one`] or
+    /// [`CondVar::notify_all`], or when a timeout occurs, or when the thread receives a signal.
+    #[must_use = "wait_interruptible_timeout returns if a signal is pending, so the caller must check the return value"]
+    pub fn wait_interruptible_timeout<T: ?Sized, B: Backend>(
+        &self,
+        guard: &mut Guard<'_, T, B>,
+        jiffies: Jiffies,
+    ) -> CondVarTimeoutResult {
+        let jiffies = jiffies.try_into().unwrap_or(MAX_SCHEDULE_TIMEOUT);
+        let res = self.wait_internal(TASK_INTERRUPTIBLE, guard, jiffies);
+
+        match (res as Jiffies, crate::current!().signal_pending()) {
+            (jiffies, true) => CondVarTimeoutResult::Signal { jiffies },
+            (0, false) => CondVarTimeoutResult::Timeout,
+            (jiffies, false) => CondVarTimeoutResult::Woken { jiffies },
+        }
+    }
+
+    /// Calls the kernel function to notify the appropriate number of threads.
+    fn notify(&self, count: c_int) {
+        // SAFETY: `wait_queue_head` points to valid memory.
         unsafe {
             bindings::__wake_up(
-                self.wait_list.get(),
-                bindings::TASK_NORMAL,
+                self.wait_queue_head.get(),
+                TASK_NORMAL,
                 count,
-                flags as _,
+                ptr::null_mut(),
             )
         };
     }
 
+    /// Calls the kernel function to notify one thread synchronously.
+    ///
+    /// This method behaves like `notify_one`, except that it hints to the scheduler that the
+    /// current thread is about to go to sleep, so it should schedule the target thread on the same
+    /// CPU.
+    pub fn notify_sync(&self) {
+        // SAFETY: `wait_queue_head` points to valid memory.
+        unsafe { bindings::__wake_up_sync(self.wait_queue_head.get(), TASK_NORMAL) };
+    }
+
     /// Wakes a single waiter up, if any.
     ///
     /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost
     /// completely (as opposed to automatically waking up the next waiter).
     pub fn notify_one(&self) {
-        self.notify(1, 0);
+        self.notify(1);
     }
 
     /// Wakes all waiters up, if any.
@@ -168,6 +218,22 @@ impl CondVar {
     /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost
     /// completely (as opposed to automatically waking up the next waiter).
     pub fn notify_all(&self) {
-        self.notify(0, 0);
+        self.notify(0);
     }
 }
+
+/// The return type of `wait_timeout`.
+pub enum CondVarTimeoutResult {
+    /// The timeout was reached.
+    Timeout,
+    /// Somebody woke us up.
+    Woken {
+        /// Remaining sleep duration.
+        jiffies: Jiffies,
+    },
+    /// A signal occurred.
+    Signal {
+        /// Remaining sleep duration.
+        jiffies: Jiffies,
+    },
+}
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index f12a684bc957..5b5c8efe427a 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -21,14 +21,21 @@ pub mod spinlock;
 /// # 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
-/// lock operation.
+///   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.
@@ -139,7 +146,7 @@ pub struct Guard<'a, T: ?Sized, B: Backend> {
 unsafe impl<T: Sync + ?Sized, B: Backend> Sync for Guard<'_, T, B> {}
 
 impl<T: ?Sized, B: Backend> Guard<'_, T, B> {
-    pub(crate) fn do_unlocked(&mut self, cb: impl FnOnce()) {
+    pub(crate) fn do_unlocked<U>(&mut self, cb: impl FnOnce() -> U) -> U {
         // SAFETY: The caller owns the lock, so it is safe to unlock it.
         unsafe { B::unlock(self.lock.state.get(), &self.state) };
 
@@ -147,7 +154,7 @@ impl<T: ?Sized, B: Backend> Guard<'_, T, B> {
         let _relock =
             ScopeGuard::new(|| unsafe { B::relock(self.lock.state.get(), &mut self.state) });
 
-        cb();
+        cb()
     }
 }
 
diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs
index 8c524a3ec45a..ef4c4634d294 100644
--- a/rust/kernel/sync/lock/mutex.rs
+++ b/rust/kernel/sync/lock/mutex.rs
@@ -17,6 +17,7 @@ macro_rules! new_mutex {
             $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!())
     };
 }
+pub use new_mutex;
 
 /// A mutual exclusion primitive.
 ///
@@ -35,7 +36,7 @@ macro_rules! new_mutex {
 /// contains an inner struct (`Inner`) that is protected by a mutex.
 ///
 /// ```
-/// use kernel::{init::InPlaceInit, init::PinInit, new_mutex, pin_init, sync::Mutex};
+/// use kernel::sync::{new_mutex, Mutex};
 ///
 /// struct Inner {
 ///     a: u32,
diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs
index 068535ce1b29..0b22c635634f 100644
--- a/rust/kernel/sync/lock/spinlock.rs
+++ b/rust/kernel/sync/lock/spinlock.rs
@@ -17,6 +17,7 @@ macro_rules! new_spinlock {
             $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!())
     };
 }
+pub use new_spinlock;
 
 /// A spinlock.
 ///
@@ -33,7 +34,7 @@ macro_rules! new_spinlock {
 /// contains an inner struct (`Inner`) that is protected by a spinlock.
 ///
 /// ```
-/// use kernel::{init::InPlaceInit, init::PinInit, new_spinlock, pin_init, sync::SpinLock};
+/// use kernel::sync::{new_spinlock, SpinLock};
 ///
 /// struct Inner {
 ///     a: u32,
@@ -112,7 +113,7 @@ unsafe impl super::Backend for SpinLockBackend {
 
     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/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 @@ use core::{cell::UnsafeCell, mem::size_of, ptr};
 /// 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
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 9451932d5d86..ca6e7e31d71c 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -5,7 +5,23 @@
 //! C header: [`include/linux/sched.h`](srctree/include/linux/sched.h).
 
 use crate::{bindings, types::Opaque};
-use core::{marker::PhantomData, ops::Deref, ptr};
+use core::{
+    ffi::{c_int, c_long, c_uint},
+    marker::PhantomData,
+    ops::Deref,
+    ptr,
+};
+
+/// A sentinel value used for infinite timeouts.
+pub const MAX_SCHEDULE_TIMEOUT: c_long = c_long::MAX;
+
+/// Bitmask for tasks that are sleeping in an interruptible state.
+pub const TASK_INTERRUPTIBLE: c_int = bindings::TASK_INTERRUPTIBLE as c_int;
+/// Bitmask for tasks that are sleeping in an uninterruptible state.
+pub const TASK_UNINTERRUPTIBLE: c_int = bindings::TASK_UNINTERRUPTIBLE as c_int;
+/// Convenience constant for waking up tasks regardless of whether they are in interruptible or
+/// uninterruptible sleep.
+pub const TASK_NORMAL: c_uint = bindings::TASK_NORMAL as c_uint;
 
 /// Returns the currently running task.
 #[macro_export]
@@ -23,7 +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
@@ -116,7 +132,7 @@ impl Task {
     /// 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`,
@@ -147,7 +163,7 @@ impl Task {
     }
 }
 
-// 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.
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
new file mode 100644
index 000000000000..25a896eed468
--- /dev/null
+++ b/rust/kernel/time.rs
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Time related primitives.
+//!
+//! This module contains the kernel APIs related to time and timers that
+//! have been ported or wrapped for usage by Rust code in the kernel.
+
+/// The time unit of Linux kernel. One jiffy equals (1/HZ) second.
+pub type Jiffies = core::ffi::c_ulong;
+
+/// The millisecond time unit.
+pub type Msecs = core::ffi::c_uint;
+
+/// Converts milliseconds to jiffies.
+#[inline]
+pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies {
+    // SAFETY: The `__msecs_to_jiffies` function is always safe to call no
+    // matter what the argument is.
+    unsafe { bindings::__msecs_to_jiffies(msecs) }
+}
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index fdb778e65d79..aa77bad9bce4 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -46,6 +46,25 @@ pub trait ForeignOwnable: Sized {
     /// Additionally, all instances (if any) of values returned by [`ForeignOwnable::borrow`] for
     /// this object must have been dropped.
     unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;
+
+    /// Tries to convert a foreign-owned object back to a Rust-owned one.
+    ///
+    /// A convenience wrapper over [`ForeignOwnable::from_foreign`] that returns [`None`] if `ptr`
+    /// is null.
+    ///
+    /// # Safety
+    ///
+    /// `ptr` must either be null or satisfy the safety requirements for
+    /// [`ForeignOwnable::from_foreign`].
+    unsafe fn try_from_foreign(ptr: *const core::ffi::c_void) -> Option<Self> {
+        if ptr.is_null() {
+            None
+        } else {
+            // SAFETY: Since `ptr` is not null here, then `ptr` satisfies the safety requirements
+            // of `from_foreign` given the safety requirements of this function.
+            unsafe { Some(Self::from_foreign(ptr)) }
+        }
+    }
 }
 
 impl<T: 'static> ForeignOwnable for Box<T> {
@@ -90,6 +109,7 @@ impl ForeignOwnable for () {
 ///
 /// 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 +128,7 @@ impl ForeignOwnable for () {
 ///
 /// 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 +150,7 @@ impl ForeignOwnable for () {
 ///
 /// 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 {
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 498397877376..544f0c51f1b7 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
 //!
@@ -35,8 +35,7 @@
 //! ```
 //! use kernel::prelude::*;
 //! use kernel::sync::Arc;
-//! use kernel::workqueue::{self, Work, WorkItem};
-//! use kernel::{impl_has_work, new_work};
+//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
 //!
 //! #[pin_data]
 //! struct MyStruct {
@@ -78,8 +77,7 @@
 //! ```
 //! use kernel::prelude::*;
 //! use kernel::sync::Arc;
-//! use kernel::workqueue::{self, Work, WorkItem};
-//! use kernel::{impl_has_work, new_work};
+//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
 //!
 //! #[pin_data]
 //! struct MyStruct {
@@ -147,6 +145,7 @@ macro_rules! new_work {
         $crate::workqueue::Work::new($crate::optional_name!($($name)?), $crate::static_lock_class!())
     };
 }
+pub use new_work;
 
 /// A kernel work queue.
 ///
@@ -168,7 +167,7 @@ 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.
@@ -218,7 +217,9 @@ impl Queue {
     }
 }
 
-/// 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]
@@ -253,14 +254,16 @@ impl<T: FnOnce()> WorkItem for ClosureWork<T> {
 /// 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
 ///
-/// 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 +293,11 @@ pub unsafe trait RawWorkItem<const ID: u64> {
 
 /// 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 +313,10 @@ 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 +334,14 @@ 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>,
@@ -396,9 +404,8 @@ impl<T: ?Sized, const ID: u64> Work<T, ID> {
 /// like this:
 ///
 /// ```no_run
-/// use kernel::impl_has_work;
 /// use kernel::prelude::*;
-/// use kernel::workqueue::Work;
+/// use kernel::workqueue::{impl_has_work, Work};
 ///
 /// struct MyWorkItem {
 ///     work_field: Work<MyWorkItem, 1>,
@@ -409,28 +416,25 @@ impl<T: ?Sized, const ID: u64> Work<T, ID> {
 /// }
 /// ```
 ///
-/// 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
 ///
-/// 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
 /// [`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.
     ///
-    /// 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
     #[inline]
     fn get_work_offset(&self) -> usize {
@@ -442,8 +446,6 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
     /// # 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.
@@ -455,8 +457,6 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
     /// # 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
@@ -473,9 +473,8 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
 /// # Examples
 ///
 /// ```
-/// use kernel::impl_has_work;
 /// use kernel::sync::Arc;
-/// use kernel::workqueue::{self, Work};
+/// use kernel::workqueue::{self, impl_has_work, Work};
 ///
 /// struct MyStruct {
 ///     work_field: Work<MyStruct, 17>,
@@ -485,8 +484,6 @@ pub unsafe trait HasWork<T, const ID: u64 = 0> {
 ///     impl HasWork<MyStruct, 17> for MyStruct { self.work_field }
 /// }
 /// ```
-///
-/// [`HasWork<T, ID>`]: HasWork
 #[macro_export]
 macro_rules! impl_has_work {
     ($(impl$(<$($implarg:ident),*>)?
@@ -509,6 +506,7 @@ macro_rules! impl_has_work {
         }
     )*};
 }
+pub use impl_has_work;
 
 impl_has_work! {
     impl<T> HasWork<Self> for ClosureWork<T> { self.work }