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SeqCst->{Release,Acquire} for xous DropLock.

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SeqCst is unnecessary. Release+Acquire is the right ordering for a
mutex.
This commit is contained in:
Mara Bos 2024-03-19 15:03:58 +01:00
parent 60ad49005a
commit 69a4d77d67
1 changed files with 6 additions and 3 deletions
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9
library/std/src/sys/pal/xous/alloc.rs
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@ -46,7 +46,10 @@ unsafe impl GlobalAlloc for System {
}
mod lock {
use crate::sync::atomic::{AtomicI32, Ordering::SeqCst};
use crate::sync::atomic::{
AtomicI32,
Ordering::{Acquire, Release},
};
static LOCKED: AtomicI32 = AtomicI32::new(0);
@ -54,7 +57,7 @@ mod lock {
pub fn lock() -> DropLock {
loop {
if LOCKED.swap(1, SeqCst) == 0 {
if LOCKED.swap(1, Acquire) == 0 {
return DropLock;
}
crate::os::xous::ffi::do_yield();
@ -63,7 +66,7 @@ mod lock {
impl Drop for DropLock {
fn drop(&mut self) {
let r = LOCKED.swap(0, SeqCst);
let r = LOCKED.swap(0, Release);
debug_assert_eq!(r, 1);
}
}