[PATCH] docs: rust: Refactor safety lines docs to sections in cpufreq.rs

From: Oliver Säfström
Date: Tue Jun 10 2025 - 11:23:31 EST

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Closes: https://github.com/Rust-for-Linux/linux/issues/1169

Signed-off-by: Oliver Säfström <safstrom.oliver@xxxxxxxxx>
Suggested-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
---
rust/kernel/cpufreq.rs | 76 +++++++++++++++++++++++++++++++-----------
1 file changed, 57 insertions(+), 19 deletions(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index b0a9c6182aec..685442135c39 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -901,12 +901,16 @@ fn register_em(_policy: &mut Policy) {
#[repr(transparent)]
pub struct Registration<T: Driver>(KBox<UnsafeCell<bindings::cpufreq_driver>>, PhantomData<T>);

-/// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
+/// # Safety
+///
+/// `Registration` doesn't offer any methods or access to fields when shared between threads
/// or CPUs, so it is safe to share it.
unsafe impl<T: Driver> Sync for Registration<T> {}

#[allow(clippy::non_send_fields_in_send_ty)]
-/// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any
+/// # Safety
+///
+/// Registration with and unregistration from the cpufreq subsystem can happen from any
/// thread.
unsafe impl<T: Driver> Send for Registration<T> {}

@@ -1055,7 +1059,9 @@ pub fn new_foreign_owned(dev: &Device<Bound>) -> Result {
impl<T: Driver> Registration<T> {
/// Driver's `init` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1070,7 +1076,9 @@ extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::

/// Driver's `exit` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
// lifetime of `policy`.
@@ -1082,7 +1090,9 @@ extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) {

/// Driver's `online` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1094,7 +1104,9 @@ extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi

/// Driver's `offline` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn offline_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1106,7 +1118,9 @@ extern "C" fn offline_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ff

/// Driver's `suspend` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn suspend_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1118,7 +1132,9 @@ extern "C" fn suspend_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ff

/// Driver's `resume` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1130,7 +1146,9 @@ extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi

/// Driver's `ready` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
// lifetime of `policy`.
@@ -1140,7 +1158,9 @@ extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) {

/// Driver's `verify` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn verify_callback(ptr: *mut bindings::cpufreq_policy_data) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1152,7 +1172,9 @@ extern "C" fn verify_callback(ptr: *mut bindings::cpufreq_policy_data) -> kernel

/// Driver's `setpolicy` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn setpolicy_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
from_result(|| {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1164,7 +1186,9 @@ extern "C" fn setpolicy_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::

/// Driver's `target` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn target_callback(
ptr: *mut bindings::cpufreq_policy,
target_freq: u32,
@@ -1180,7 +1204,9 @@ extern "C" fn target_callback(

/// Driver's `target_index` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn target_index_callback(
ptr: *mut bindings::cpufreq_policy,
index: u32,
@@ -1200,7 +1226,9 @@ extern "C" fn target_index_callback(

/// Driver's `fast_switch` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn fast_switch_callback(
ptr: *mut bindings::cpufreq_policy,
target_freq: u32,
@@ -1225,7 +1253,9 @@ extern "C" fn adjust_perf_callback(

/// Driver's `get_intermediate` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn get_intermediate_callback(
ptr: *mut bindings::cpufreq_policy,
index: u32,
@@ -1243,7 +1273,9 @@ extern "C" fn get_intermediate_callback(

/// Driver's `target_intermediate` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn target_intermediate_callback(
ptr: *mut bindings::cpufreq_policy,
index: u32,
@@ -1276,7 +1308,9 @@ extern "C" fn update_limits_callback(ptr: *mut bindings::cpufreq_policy) {

/// Driver's `bios_limit` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int {
from_result(|| {
let mut policy = PolicyCpu::from_cpu(cpu as u32)?;
@@ -1288,7 +1322,9 @@ extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_i

/// Driver's `set_boost` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn set_boost_callback(
ptr: *mut bindings::cpufreq_policy,
state: i32,
@@ -1303,7 +1339,9 @@ extern "C" fn set_boost_callback(

/// Driver's `register_em` callback.
///
- /// SAFETY: Called from C. Inputs must be valid pointers.
+ /// # Safety
+ ///
+ /// Called from C. Inputs must be valid pointers.
extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) {
// SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
// lifetime of `policy`.
--
2.49.0

Next message: Mark Bloch: "[PATCH net 1/9] net/mlx5: Ensure fw pages are always allocated on same NUMA"
Previous message: Conor Dooley: "Re: [PATCH v2 1/2] dt-bindings: iio: temperature: add support for MCP998X"
Next in thread: Miguel Ojeda: "Re: [PATCH] docs: rust: Refactor safety lines docs to sections in cpufreq.rs"
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