mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-16 06:41:39 -04:00
Code Issues Packages Projects Releases Wiki Activity

rust: time: make ClockSource unsafe trait

Browse Source 
Mark the ClockSource trait as unsafe and document its safety
requirements. Specifically, implementers must guarantee that their
`ktime_get()` implementation returns a value in the inclusive range
[0, KTIME_MAX].

Update all existing implementations to use `unsafe impl` with
corresponding safety comments.

Note that there could be potential users of a customized clock source [1]
so we don't seal the trait.

Link: https://lore.kernel.org/rust-for-linux/Z9xb1r1x5tOzAIZT@boqun-archlinux/ [1]
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://msgid.link/20250630131011.405219-1-fujita.tomonori@gmail.com
[ Change range expressions in docs. - Andreas ]
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
This commit is contained in:
FUJITA Tomonori
2025-06-30 22:10:11 +09:00
committed by Andreas Hindborg
parent c51866f65b
commit 67b598db7e
1 changed files with 20 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
rust/kernel/time.rs
View File

@@ -60,7 +60,13 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies {
/// cases the user of the clock has to decide which clock is best suited for the
/// purpose. In most scenarios clock [`Monotonic`] is the best choice as it
/// provides a accurate monotonic notion of time (leap second smearing ignored).
pub trait ClockSource {
///
/// # Safety
///
/// Implementers must ensure that `ktime_get()` returns a value in the inclusive range
/// `0..=KTIME_MAX` (i.e., greater than or equal to 0 and less than or equal to
/// `KTIME_MAX`, where `KTIME_MAX` equals `i64::MAX`).
pub unsafe trait ClockSource {
/// The kernel clock ID associated with this clock source.
///
/// This constant corresponds to the C side `clockid_t` value.
@@ -68,7 +74,7 @@ pub trait ClockSource {
/// Get the current time from the clock source.
///
/// The function must return a value in the range from 0 to `KTIME_MAX`.
/// The function must return a value in the range `0..=KTIME_MAX`.
fn ktime_get() -> bindings::ktime_t;
}
@@ -85,7 +91,9 @@ pub trait ClockSource {
/// count time that the system is suspended.
pub struct Monotonic;
impl ClockSource for Monotonic {
// SAFETY: The kernel's `ktime_get()` is guaranteed to return a value
// in `0..=KTIME_MAX`.
unsafe impl ClockSource for Monotonic {
const ID: bindings::clockid_t = bindings::CLOCK_MONOTONIC as bindings::clockid_t;
fn ktime_get() -> bindings::ktime_t {
@@ -110,7 +118,9 @@ fn ktime_get() -> bindings::ktime_t {
/// the clock will experience discontinuity around leap second adjustment.
pub struct RealTime;
impl ClockSource for RealTime {
// SAFETY: The kernel's `ktime_get_real()` is guaranteed to return a value
// in `0..=KTIME_MAX`.
unsafe impl ClockSource for RealTime {
const ID: bindings::clockid_t = bindings::CLOCK_REALTIME as bindings::clockid_t;
fn ktime_get() -> bindings::ktime_t {
@@ -128,7 +138,9 @@ fn ktime_get() -> bindings::ktime_t {
/// discontinuities if the time is changed using settimeofday(2) or similar.
pub struct BootTime;
impl ClockSource for BootTime {
// SAFETY: The kernel's `ktime_get_boottime()` is guaranteed to return a value
// in `0..=KTIME_MAX`.
unsafe impl ClockSource for BootTime {
const ID: bindings::clockid_t = bindings::CLOCK_BOOTTIME as bindings::clockid_t;
fn ktime_get() -> bindings::ktime_t {
@@ -150,7 +162,9 @@ fn ktime_get() -> bindings::ktime_t {
/// The acronym TAI refers to International Atomic Time.
pub struct Tai;
impl ClockSource for Tai {
// SAFETY: The kernel's `ktime_get_clocktai()` is guaranteed to return a value
// in `0..=KTIME_MAX`.
unsafe impl ClockSource for Tai {
const ID: bindings::clockid_t = bindings::CLOCK_TAI as bindings::clockid_t;
fn ktime_get() -> bindings::ktime_t {