RCU-free radix_node

Not actually doing anything with RCU yet, but we will at some point.

RCU-free radix_node
1d7f9493 · David Benjamin · 41cde26a · 1d7f9493 · 1d7f9493
--- a/include/radix.hh
+++ b/include/radix.hh
@@ -23,12 +23,15 @@ class radix_elem : public rcu_freed {
  void incref() { ref_++; }
 };

-struct radix_node {
+struct radix_node : public rcu_freed {
  markptr<void> ptr[1 << bits_per_level];
-  radix_node() {
+  radix_node() : rcu_freed("radix_node") {
    for (int i = 0; i < sizeof(ptr) / sizeof(ptr[0]); i++)
      ptr[i] = 0;
  }
+
+  virtual void do_gc() { delete this; }
+
  NEW_DELETE_OPS(radix_node)
 };

@@ -39,6 +42,8 @@ struct radix_range {
  u64 start_;
  u64 size_;

+  scoped_gc_epoch gc_;
+
  radix_range(radix* r, u64 start, u64 size);
  radix_range(radix_range&&);
  ~radix_range();

--- a/kernel/radix.cc
+++ b/kernel/radix.cc
@@ -51,6 +51,7 @@ radix_elem*
 radix::search(u64 key)
 {
  radix_elem *result = 0;
+  scoped_gc_epoch gc;
  descend(key >> shift_, &root_, radix_levels-1, [&result](markptr<void> *v) {
      result = (radix_elem*) v->ptr().load();
    }, false);