linux-kernel - [PATCH v2 5/5] rust: task: Add Rust version of might

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Message-Id: <20250625051518.15255-6-boqun.feng@gmail.com>
Date: Tue, 24 Jun 2025 22:15:18 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>,	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,	Valentin Schneider <vschneid@...hat.com>,
	Miguel Ojeda <ojeda@...nel.org>,	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,	Justin Stitt <justinstitt@...gle.com>,
	FUJITA Tomonori <fujita.tomonori@...il.com>,
	Tamir Duberstein <tamird@...il.com>,	Kunwu Chan <kunwu.chan@...mail.com>,
	Mitchell Levy <levymitchell0@...il.com>,
	Martin Rodriguez Reboredo <yakoyoku@...il.com>,
	Borys Tyran <borys.tyran@...tonmail.com>,
	Christian Brauner <brauner@...nel.org>,
	Panagiotis Foliadis <pfoliadis@...teo.net>,	linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org,	llvm@...ts.linux.dev
Subject: [PATCH v2 5/5] rust: task: Add Rust version of might_sleep()

From: FUJITA Tomonori <fujita.tomonori@...il.com>

Add a helper function equivalent to the C's might_sleep(), which
serves as a debugging aid and a potential scheduling point.

Note that this function can only be used in a nonatomic context.

This will be used by Rust version of read_poll_timeout().

[boqun: Use file_from_location() to get a C string instead of changing
__might_sleep()]

Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
Link: https://lore.kernel.org/r/20250619151007.61767-3-boqun.feng@gmail.com
---
 rust/helpers/task.c |  6 ++++++
 rust/kernel/task.rs | 24 ++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/rust/helpers/task.c b/rust/helpers/task.c
index 31c33ea2dce6..2c85bbc2727e 100644
--- a/rust/helpers/task.c
+++ b/rust/helpers/task.c
@@ -1,7 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0
 
+#include <linux/kernel.h>
 #include <linux/sched/task.h>
 
+void rust_helper_might_resched(void)
+{
+	might_resched();
+}
+
 struct task_struct *rust_helper_get_current(void)
 {
 	return current;
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 834368313088..7d0935bc325c 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -400,3 +400,27 @@ fn eq(&self, other: &Kuid) -> bool {
 }
 
 impl Eq for Kuid {}
+
+/// Annotation for functions that can sleep.
+///
+/// Equivalent to the C side [`might_sleep()`], this function serves as
+/// a debugging aid and a potential scheduling point.
+///
+/// This function can only be used in a nonatomic context.
+///
+/// [`might_sleep()`]: https://docs.kernel.org/driver-api/basics.html#c.might_sleep
+#[track_caller]
+#[inline]
+pub fn might_sleep() {
+    #[cfg(CONFIG_DEBUG_ATOMIC_SLEEP)]
+    {
+        let loc = core::panic::Location::caller();
+        let file = kernel::file_from_location(loc);
+
+        // SAFETY: `file.as_ptr()` is valid for reading and guaranteed to be nul-terminated.
+        unsafe { crate::bindings::__might_sleep(file.as_ptr().cast(), loc.line() as i32) }
+    }
+
+    // SAFETY: Always safe to call.
+    unsafe { crate::bindings::might_resched() }
+}
-- 
2.39.5 (Apple Git-154)