Merge pull request #791 from compnerd/atomic-memset

compnerd · web-flow · commit 2725ced65c9d · 2023-05-24T07:14:27.000-07:00
shims: fix a subtle bug in semaphore initialisation on Windows
diff --git a/src/shims/lock.c b/src/shims/lock.c
@@ -266,6 +266,7 @@ void _dispatch_sema4_init(_dispatch_sema4_t *sema, int policy DISPATCH_UNUSED)
 
 	// lazily allocate the semaphore port
 
+	os_atomic_cmpxchg(sema, *sema, 0, relaxed);
 	while (!dispatch_assume(tmp = CreateSemaphore(NULL, 0, LONG_MAX, NULL))) {
 		_dispatch_temporary_resource_shortage();
 	}

Original file line number	Diff line number	Diff line change
`@@ -266,6 +266,7 @@ void _dispatch_sema4_init(_dispatch_sema4_t *sema, int policy DISPATCH_UNUSED)`
`266`	`266`
`267`	`267`	`// lazily allocate the semaphore port`
`268`	`268`
	`269`	`+ os_atomic_cmpxchg(sema, *sema, 0, relaxed);`
`269`	`270`	`while (!dispatch_assume(tmp = CreateSemaphore(NULL, 0, LONG_MAX, NULL))) {`
`270`	`271`	`_dispatch_temporary_resource_shortage();`
`271`	`272`	`}`