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Message-ID: <20241025033118.44452-5-fujita.tomonori@gmail.com>
Date: Fri, 25 Oct 2024 12:31:15 +0900
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: anna-maria@...utronix.de,
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Subject: [PATCH v4 4/7] rust: time: Add wrapper for fsleep function
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@...il.com>
---
rust/helpers/helpers.c | 1 +
rust/helpers/time.c | 8 ++++++++
rust/kernel/time.rs | 4 +++-
rust/kernel/time/delay.rs | 30 ++++++++++++++++++++++++++++++
4 files changed, 42 insertions(+), 1 deletion(-)
create mode 100644 rust/helpers/time.c
create mode 100644 rust/kernel/time/delay.rs
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 30f40149f3a9..c274546bcf78 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -21,6 +21,7 @@
#include "slab.c"
#include "spinlock.c"
#include "task.c"
+#include "time.c"
#include "uaccess.c"
#include "wait.c"
#include "workqueue.c"
diff --git a/rust/helpers/time.c b/rust/helpers/time.c
new file mode 100644
index 000000000000..7ae64ad8141d
--- /dev/null
+++ b/rust/helpers/time.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/delay.h>
+
+void rust_helper_fsleep(unsigned long usecs)
+{
+ fsleep(usecs);
+}
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
index 3cc1a8a76777..cfc31f908710 100644
--- a/rust/kernel/time.rs
+++ b/rust/kernel/time.rs
@@ -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;
diff --git a/rust/kernel/time/delay.rs b/rust/kernel/time/delay.rs
new file mode 100644
index 000000000000..f80f35f50949
--- /dev/null
+++ b/rust/kernel/time/delay.rs
@@ -0,0 +1,30 @@
+// 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 crate::time;
+use core::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.
+///
+/// The function sleeps infinitely (MAX_JIFFY_OFFSET) if `Delta` is negative
+/// or exceedes i32::MAX milliseconds.
+///
+/// This function can only be used in a nonatomic context.
+pub fn fsleep(delta: time::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(delta.as_micros_ceil() as c_ulong)
+ }
+}
--
2.43.0
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