From fd36326ee720972396891c3c7d26d43ff7f11d8d Mon Sep 17 00:00:00 2001
From: Zhu Zihao <all_but_last@163.com>
Date: Sun, 4 Jul 2021 23:26:34 +0800
Subject: [PATCH] Simplify the implmentation of SpinLock.

Use 'store' instead of CAS to unlock spinlock.
---
 src/spinlock.rs | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/spinlock.rs b/src/spinlock.rs
index c760a429..6440ba01 100644
--- a/src/spinlock.rs
+++ b/src/spinlock.rs
@@ -69,12 +69,9 @@ impl<'mutex, T: ?Sized> DerefMut for SpinLockGuard<'mutex, T> {
 impl<'a, T: ?Sized> Drop for SpinLockGuard<'a, T> {
     #[inline]
     fn drop(&mut self) {
-        while self
-            .__lock
-            .locked
-            .compare_exchange(true, false, Ordering::SeqCst, Ordering::SeqCst)
-            .is_err()
-        {}
+        // Safety: While a SpinLock is locked, othre thread cannot acquire the
+        // lock, its internal status cannot be changed, no CAS needed.
+        self.__lock.locked.store(false, Ordering::SeqCst);
     }
 }