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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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//! Delay and sleep primitives.//!//! This module contains the kernel APIs related to delay and sleep that//! have been ported or wrapped for usage by Rust code in the kernel.//!//! C header: [`include/linux/delay.h`](srctree/include/linux/delay.h).
use super::Delta;use crate::prelude::*;
/// Sleeps for a given duration at least.////// Equivalent to the C side [`fsleep()`], flexible sleep function,/// which automatically chooses the best sleep method based on a duration.////// `delta` must be within `[0, i32::MAX]` microseconds;/// otherwise, it is erroneous behavior. That is, it is considered a bug/// to call this function with an out-of-range value, in which case the function/// will sleep for at least the maximum value in the range and may warn/// in the future.////// The behavior above differs from the C side [`fsleep()`] for which out-of-range/// values mean "infinite timeout" instead.////// This function can only be used in a nonatomic context.////// [`fsleep()`]: https://docs.kernel.org/timers/delay_sleep_functions.html#c.fsleeppub fn fsleep(delta: Delta) { // The maximum value is set to `i32::MAX` microseconds to prevent integer // overflow inside fsleep, which could lead to unintentional infinite sleep. const MAX_DELTA: Delta = Delta::from_micros(i32::MAX as i64);
let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) { delta } else { // TODO: Add WARN_ONCE() when it's supported. MAX_DELTA };
// SAFETY: It is always safe to call `fsleep()` with any duration. unsafe { // Convert the duration to microseconds and round up to preserve // the guarantee; `fsleep()` sleeps for at least the provided duration, // but that it may sleep for longer under some circumstances. bindings::fsleep(delta.as_micros_ceil() as c_ulong) }}
/// Inserts a delay based on microseconds with busy waiting.////// Equivalent to the C side [`udelay()`], which delays in microseconds.////// `delta` must be within `[0, MAX_UDELAY_MS]` in milliseconds;/// otherwise, it is erroneous behavior. That is, it is considered a bug to/// call this function with an out-of-range value.////// The behavior above differs from the C side [`udelay()`] for which out-of-range/// values could lead to an overflow and unexpected behavior.////// [`udelay()`]: https://docs.kernel.org/timers/delay_sleep_functions.html#c.udelaypub fn udelay(delta: Delta) { const MAX_UDELAY_DELTA: Delta = Delta::from_millis(bindings::MAX_UDELAY_MS as i64);
debug_assert!(delta.as_nanos() >= 0); debug_assert!(delta <= MAX_UDELAY_DELTA);
let delta = if (Delta::ZERO..=MAX_UDELAY_DELTA).contains(&delta) { delta } else { MAX_UDELAY_DELTA };
// SAFETY: It is always safe to call `udelay()` with any duration. // Note that the kernel is compiled with `-fno-strict-overflow` // so any out-of-range value could lead to unexpected behavior // but won't lead to undefined behavior. unsafe { // Convert the duration to microseconds and round up to preserve // the guarantee; `udelay()` inserts a delay for at least // the provided duration, but that it may delay for longer // under some circumstances. bindings::udelay(delta.as_micros_ceil() as c_ulong) }}