- while (futex_noasync(&waiter->state, FUTEX_WAIT, WAITER_WAITING,
- NULL, NULL, 0)) {
+ while (uatomic_read(&waiter->state) == WAITER_WAITING) {
+ if (!futex_noasync(
+ &waiter->state, FUTEX_WAIT, WAITER_WAITING, nullptr, nullptr, 0)) {
+ /*
+ * Prior queued wakeups queued by unrelated code
+ * using the same address can cause futex wait to
+ * return 0 even through the futex value is still
+ * WAITER_WAITING (spurious wakeups). Check
+ * the value again in user-space to validate
+ * whether it really differs from WAITER_WAITING.
+ */
+ continue;
+ }