linux commit 575b1967e10a1f3038266244d2c7a3ca6b99fed8 moved timerfd apis to a new uapi header which showed musl was missing this flag.
@@ -12,6 +12,7 @@ extern "C" {
#define TFD_CLOEXEC O_CLOEXEC
#define TFD_TIMER_ABSTIME 1
+#define TFD_TIMER_CANCEL_ON_SET (1 << 1)
struct itimerspec;