- if (uatomic_read(futex) != -1)
- goto end;
- while (futex_async(futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+ while (uatomic_read(futex) == -1) {
+ if (!futex_async(futex, FUTEX_WAIT, -1, NULL, NULL, 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
+ * -1 (spurious wakeups). Check the value again
+ * in user-space to validate whether it really
+ * differs from -1.
+ */
+ continue;
+ }