linux-kernel - [PATCH] rust: sync: Makes `CondVar::wait()` an uninterruptible wait

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Date: Thu, 14 Dec 2023 12:04:21 -0800
From: Boqun Feng <boqun.feng@...il.com>
To: rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Tiago Lam <tiagolam@...il.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Wedson Almeida Filho <wedsonaf@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...sung.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Martin Rodriguez Reboredo <yakoyoku@...il.com>,
	Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH] rust: sync: Makes `CondVar::wait()` an uninterruptible wait

Currently, `CondVar::wait()` is an interruptible wait, and this is
different than `wait_event()` in include/linux/wait.h (which is an
uninterruptible wait). To avoid confusion between different APIs on the
interruptible/uninterruptible, make `CondVar::wait()` an uninterruptible
wait same as `wait_event()`, also rename the old `wait()` to
`CondVar::wait_interruptible()`.

Spotted-by: Tiago Lam <tiagolam@...il.com>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---
 rust/kernel/sync/condvar.rs | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index b679b6f6dbeb..8630faa29b78 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -50,7 +50,7 @@ macro_rules! new_condvar {
 /// fn wait_for_value(e: &Example, v: u32) {
 ///     let mut guard = e.value.lock();
 ///     while *guard != v {
-///         e.value_changed.wait_uninterruptible(&mut guard);
+///         e.value_changed.wait(&mut guard);
 ///     }
 /// }
 ///
@@ -120,28 +120,28 @@ fn wait_internal<T: ?Sized, B: Backend>(&self, wait_state: u32, guard: &mut Guar
         unsafe { bindings::finish_wait(self.wait_list.get(), wait.get()) };
     }
 
-    /// Releases the lock and waits for a notification in interruptible mode.
+    /// Releases the lock and waits for a notification in uninterruptible mode.
     ///
     /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the
     /// thread to sleep, reacquiring the lock on wake up. It wakes up when notified by
-    /// [`CondVar::notify_one`] or [`CondVar::notify_all`], or when the thread receives a signal.
-    /// It may also wake up spuriously.
+    /// [`CondVar::notify_one`] or [`CondVar::notify_all`]. Note that it may also wake up
+    /// spuriously.
+    pub fn wait<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) {
+        self.wait_internal(bindings::TASK_UNINTERRUPTIBLE, guard);
+    }
+
+    /// Releases the lock and waits for a notification in interruptible mode.
+    ///
+    /// Similar to [`CondVar::wait`], except that the wait is interruptible. That is, the thread may
+    /// wake up due to signals. It may also wake up spuriously.
     ///
     /// Returns whether there is a signal pending.
-    #[must_use = "wait returns if a signal is pending, so the caller must check the return value"]
-    pub fn wait<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) -> bool {
+    #[must_use = "wait_interruptible returns if a signal is pending, so the caller must check the return value"]
+    pub fn wait_interruptible<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) -> bool {
         self.wait_internal(bindings::TASK_INTERRUPTIBLE, guard);
         crate::current!().signal_pending()
     }
 
-    /// Releases the lock and waits for a notification in uninterruptible mode.
-    ///
-    /// Similar to [`CondVar::wait`], except that the wait is not interruptible. That is, the
-    /// thread won't wake up due to signals. It may, however, wake up supirously.
-    pub fn wait_uninterruptible<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) {
-        self.wait_internal(bindings::TASK_UNINTERRUPTIBLE, guard)
-    }
-
     /// Calls the kernel function to notify the appropriate number of threads with the given flags.
     fn notify(&self, count: i32, flags: u32) {
         // SAFETY: `wait_list` points to valid memory.
-- 
2.43.0