fix bug in synccall with no threads: lock was taken but never released

diff --git a/src/thread/synccall.c b/src/thread/synccall.c
index 7c4f92b..91ac5eb 100644 (file)
--- a/src/thread/synccall.c
+++ b/src/thread/synccall.c
@@ -54,15 +54,15 @@ void __synccall(void (*func)(void *), void *ctx)
        struct chain *cur, *next;
        uint64_t oldmask;
 
-       pthread_rwlock_wrlock(&lock);
-
-       __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &oldmask, 8);
-
        if (!libc.threads_minus_1) {
                func(ctx);
                return;
        }
 
+       pthread_rwlock_wrlock(&lock);
+
+       __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &oldmask, 8);
+
        sem_init(&chaindone, 0, 0);
        sem_init(&chainlock, 0, 1);
        chainlen = 0;