@@ -26,6 +26,7 @@
#include "slab.c"
#include "spinlock.c"
#include "task.c"
+#include "time.c"
#include "uaccess.c"
#include "vmalloc.c"
#include "wait.c"
new file mode 100644
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/delay.h>
+
+void rust_helper_fsleep(unsigned long usecs)
+{
+ fsleep(usecs);
+}
@@ -2,12 +2,14 @@
//! Time related primitives.
//!
-//! This module contains the kernel APIs related to time and timers that
+//! This module contains the kernel APIs related to time that
//! have been ported or wrapped for usage by Rust code in the kernel.
//!
//! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h).
//! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h).
+pub mod delay;
+
/// The number of nanoseconds per microsecond.
pub const NSEC_PER_USEC: i64 = bindings::NSEC_PER_USEC as i64;
new file mode 100644
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! 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::ffi::c_ulong;
+
+/// Sleeps for a given duration at least.
+///
+/// Equivalent to the kernel's [`fsleep`], flexible sleep function,
+/// which automatically chooses the best sleep method based on a duration.
+///
+/// `delta` must be 0 or greater and no more than `u32::MAX / 2` microseconds.
+/// If a value outside the range is given, the function will sleep
+/// for `u32::MAX / 2` microseconds (= ~2147 seconds or ~36 minutes) at least.
+///
+/// This function can only be used in a nonatomic context.
+pub fn fsleep(delta: Delta) {
+ // The argument of fsleep is an unsigned long, 32-bit on 32-bit architectures.
+ // Considering that fsleep rounds up the duration to the nearest millisecond,
+ // set the maximum value to u32::MAX / 2 microseconds.
+ const MAX_DURATION: Delta = Delta::from_micros(u32::MAX as i64 >> 1);
+
+ let duration = if delta > MAX_DURATION || delta.is_negative() {
+ // TODO: add WARN_ONCE() when it's supported.
+ MAX_DURATION
+ } else {
+ delta
+ };
+
+ // SAFETY: FFI call.
+ 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(duration.as_micros_ceil() as c_ulong)
+ }
+}
Add a wrapper for fsleep, flexible sleep functions in `include/linux/delay.h` which typically deals with hardware delays. The kernel supports several `sleep` functions to handle various lengths of delay. This adds fsleep, automatically chooses the best sleep method based on a duration. `sleep` functions including `fsleep` belongs to TIMERS, not TIMEKEEPING. They are maintained separately. rust/kernel/time.rs is an abstraction for TIMEKEEPING. To make Rust abstractions match the C side, add rust/kernel/time/delay.rs for this wrapper. fsleep() can only be used in a nonatomic context. This requirement is not checked by these abstractions, but it is intended that klint [1] or a similar tool will be used to check it in the future. Link: https://rust-for-linux.com/klint [1] Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com> --- rust/helpers/helpers.c | 1 + rust/helpers/time.c | 8 ++++++++ rust/kernel/time.rs | 4 +++- rust/kernel/time/delay.rs | 43 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 55 insertions(+), 1 deletion(-) create mode 100644 rust/helpers/time.c create mode 100644 rust/kernel/time/delay.rs