8000 Fix for corner case where `RwLock` could be acquired in write mode while write locked by Pointerbender · Pull Request #300 · tokio-rs/loom · GitHub
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Fix for corner case where RwLock could be acquired in write mode while write locked #300

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Merged
merged 1 commit into from
Feb 2, 2023
Merged

Fix for corner case where RwLock could be acquired in write mode while write locked #300

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3 changes: 2 additions & 1 deletion src/rt/rwlock.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -230,7 +230,8 @@ impl RwLock {
// Set the lock to the current thread
state.lock = match state.lock {
Some(Locked::Read(_)) => return false,
_ => Some(Locked::Write(thread_id)),
Some(Locked::Write(_)) => return false,
None => Some(Locked::Write(thread_id)),
};

state.synchronize.sync_load(&mut execution.threads, Acquire);
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64 changes: 63 additions & 1 deletion tests/rwlock.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
use loom::sync::{Arc, RwLock};
use loom::sync::{Arc, RwLock, TryLockResult};
use loom::thread;

use std::rc::Rc;
use std::sync::TryLockError;

#[test]
fn rwlock_read_one() {
Expand Down Expand Up @@ -41,6 +42,67 @@ fn rwlock_read_two_write_one() {
});
}

#[test]
fn rwlock_write_three() {
loom::model(|| {
let lock = Arc::new(RwLock::new(1));

for _ in 0..2 {
let lock = lock.clone();
thread::spawn(move || {
let _l = lock.write().unwrap();

thread::yield_now();
});
}

let _l = lock.write().unwrap();
thread::yield_now();
});
}

#[test]
fn rwlock_write_then_try_write() {
loom::model(|| {
let lock = Arc::new(RwLock::new(1));

let _l1 = lock.write().unwrap();

assert!(matches!(
lock.try_write(),
TryLockResult::Err(TryLockError::WouldBlock)
));
});
}

#[test]
fn rwlock_write_then_try_read() {
loom::model(|| {
let lock = Arc::new(RwLock::new(1));

let _l1 = lock.write().unwrap();

assert!(matches!(
lock.try_read(),
TryLockResult::Err(TryLockError::WouldBlock)
));
});
}

#[test]
fn rwlock_read_then_try_write() {
loom::model(|| {
let lock = Arc::new(RwLock::new(1));

let _l1 = lock.write().unwrap();

assert!(matches!(
lock.try_write(),
TryLockResult::Err(TryLockError::WouldBlock)
));
});
}

#[test]
fn rwlock_try_read() {
loom::model(|| {
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0