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eliminate global waiters count in pthread_once
[musl]
/
src
/
thread
/
pthread_once.c
diff --git
a/src/thread/pthread_once.c
b/src/thread/pthread_once.c
index
b7388b9
..
7c47385
100644
(file)
--- a/
src/thread/pthread_once.c
+++ b/
src/thread/pthread_once.c
@@
-2,14
+2,14
@@
static void undo(void *control)
{
static void undo(void *control)
{
- a_store(control, 0);
- __wake(control, 1, 1);
+ /* Wake all waiters, since the waiter status is lost when
+ * resetting control to the initial state. */
+ if (a_swap(control, 0) == 3)
+ __wake(control, -1, 1);
}
int __pthread_once(pthread_once_t *control, void (*init)(void))
{
}
int __pthread_once(pthread_once_t *control, void (*init)(void))
{
- static int waiters;
-
/* Return immediately if init finished before, but ensure that
* effects of the init routine are visible to the caller. */
if (*control == 2) {
/* Return immediately if init finished before, but ensure that
* effects of the init routine are visible to the caller. */
if (*control == 2) {
@@
-17,10
+17,11
@@
int __pthread_once(pthread_once_t *control, void (*init)(void))
return 0;
}
return 0;
}
- /* Try to enter initializing state.
Three
possibilities:
+ /* Try to enter initializing state.
Four
possibilities:
* 0 - we're the first or the other cancelled; run init
* 1 - another thread is running init; wait
* 0 - we're the first or the other cancelled; run init
* 1 - another thread is running init; wait
- * 2 - another thread finished running init; just return */
+ * 2 - another thread finished running init; just return
+ * 3 - another thread is running init, waiters present; wait */
for (;;) switch (a_cas(control, 0, 1)) {
case 0:
for (;;) switch (a_cas(control, 0, 1)) {
case 0:
@@
-28,11
+29,14
@@
int __pthread_once(pthread_once_t *control, void (*init)(void))
init();
pthread_cleanup_pop(0);
init();
pthread_cleanup_pop(0);
- a_store(control, 2);
-
if (waiters)
__wake(control, -1, 1);
+ if (a_swap(control, 2) == 3)
+
__wake(control, -1, 1);
return 0;
case 1:
return 0;
case 1:
- __wait(control, &waiters, 1, 1);
+ /* If this fails, so will __wait. */
+ a_cas(control, 1, 3);
+ case 3:
+ __wait(control, 0, 3, 1);
continue;
case 2:
return 0;
continue;
case 2:
return 0;