Fix unsafe operation of wasm32::memory_atomic_notify

chansuke · chansuke · commit d147f78e3673 · 2020-10-24T18:14:17.000+09:00
diff --git a/library/std/src/sys/wasm/condvar_atomics.rs b/library/std/src/sys/wasm/condvar_atomics.rs
@@ -52,8 +52,9 @@ impl Condvar {
 
     #[inline]
     pub unsafe fn notify_all(&self) {
+        self.cnt.fetch_add(1, SeqCst);
+        // SAFETY: memory_atomic_notify()is always valid
         unsafe {
-            self.cnt.fetch_add(1, SeqCst);
             wasm32::memory_atomic_notify(self.ptr(), u32::MAX); // -1 == "wake everyone"
         }
     }

Original file line number	Diff line number	Diff line change
`@@ -52,8 +52,9 @@ impl Condvar {`
`52`	`52`
`53`	`53`	`#[inline]`
`54`	`54`	`pub unsafe fn notify_all(&self) {`
	`55`	`+ self.cnt.fetch_add(1, SeqCst);`
	`56`	`+ // SAFETY: memory_atomic_notify()is always valid`
`55`	`57`	`unsafe {`
`56`		`- self.cnt.fetch_add(1, SeqCst);`
`57`	`58`	`wasm32::memory_atomic_notify(self.ptr(), u32::MAX); // -1 == "wake everyone"`
`58`	`59`	`}`
`59`	`60`	`}`