Hold scoped_gc_epoch for fewer instructions

264a783d · Silas Boyd-Wickizer · 9e839f9a · 264a783d
--- a/kernel/futex.cc
+++ b/kernel/futex.cc
@@ -228,10 +228,12 @@ futexwake(futexkey_t key, u64 nwake)
  if (nwake == 0)
    return -1;

-  scoped_gc_epoch gc;
-  fa = nsfutex->lookup(key);
-  if (fa == nullptr || !fa->tryinc())
-    return 0;
+  {
+    scoped_gc_epoch gc;
+    fa = nsfutex->lookup(key);
+    if (fa == nullptr || !fa->tryinc())
+      return 0;
+  }

  auto cleanup = scoped_cleanup([&fa](){
    fa->dec();