fix fallback checks for kernels without private futex support

for unknown syscall commands, the kernel produces ENOSYS, not EINVAL.

src/internal/pthread_impl.h

@@ -112,7 +112,7 @@ static inline void __wake(volatile void *addr, int cnt, int priv)
 {
 	if (priv) priv = 128;
 	if (cnt<0) cnt = INT_MAX;
-	__syscall(SYS_futex, addr, FUTEX_WAKE|priv, cnt) != -EINVAL ||
+	__syscall(SYS_futex, addr, FUTEX_WAKE|priv, cnt) != -ENOSYS ||
 	__syscall(SYS_futex, addr, FUTEX_WAKE, cnt);
 }
 

src/thread/__timedwait.c

@@ -29,7 +29,7 @@ int __timedwait(volatile int *addr, int val,
 	pthread_cleanup_push(cleanup, arg);
 
 	r = -__syscall_cp(SYS_futex, addr, FUTEX_WAIT|priv, val, top);
-	if (r == EINVAL) r = -__syscall_cp(SYS_futex, addr, FUTEX_WAIT, val, top);
+	if (r == ENOSYS) r = -__syscall_cp(SYS_futex, addr, FUTEX_WAIT, val, top);
 	if (r != EINTR && r != ETIMEDOUT) r = 0;
 
 	pthread_cleanup_pop(0);

src/thread/__wait.c

@@ -10,7 +10,7 @@ void __wait(volatile int *addr, volatile int *waiters, int val, int priv)
 	}
 	if (waiters) a_inc(waiters);
 	while (*addr==val) {
-		__syscall(SYS_futex, addr, FUTEX_WAIT|priv, val, 0) != -EINVAL
+		__syscall(SYS_futex, addr, FUTEX_WAIT|priv, val, 0) != -ENOSYS
 		|| __syscall(SYS_futex, addr, FUTEX_WAIT, val, 0);
 	}
 	if (waiters) a_dec(waiters);

src/thread/pthread_barrier_wait.c

@@ -87,7 +87,7 @@ int pthread_barrier_wait(pthread_barrier_t *b)
 			a_spin();
 		a_inc(&inst->finished);
 		while (inst->finished == 1)
-			__syscall(SYS_futex,&inst->finished,FUTEX_WAIT|128,1,0) != -EINTR
+			__syscall(SYS_futex,&inst->finished,FUTEX_WAIT|128,1,0) != -ENOSYS
 			|| __syscall(SYS_futex,&inst->finished,FUTEX_WAIT,1,0);
 		return PTHREAD_BARRIER_SERIAL_THREAD;
 	}

src/thread/pthread_cond_timedwait.c

@@ -52,7 +52,7 @@ static inline void unlock_requeue(volatile int *l, volatile int *r, int w)
 {
 	a_store(l, 0);
 	if (w) __wake(l, 1, 1);
-	else __syscall(SYS_futex, l, FUTEX_REQUEUE|128, 0, 1, r) != -EINVAL
+	else __syscall(SYS_futex, l, FUTEX_REQUEUE|128, 0, 1, r) != -ENOSYS
 		|| __syscall(SYS_futex, l, FUTEX_REQUEUE, 0, 1, r);
 }