network: fix tsan test flake (envoyproxy#32631)

Fixes envoyproxy#32527

Signed-off-by: Greg Greenway <[email protected]>

source/common/network/address_impl.cc

@@ -213,18 +213,18 @@ std::string Ipv4Instance::sockaddrToString(const sockaddr_in& addr) {
 }
 
 namespace {
-bool force_ipv4_unsupported_for_test = false;
+std::atomic<bool> force_ipv4_unsupported_for_test = false;
 }
 
 Cleanup Ipv4Instance::forceProtocolUnsupportedForTest(bool new_val) {
-  bool old_val = force_ipv4_unsupported_for_test;
-  force_ipv4_unsupported_for_test = new_val;
-  return {[old_val]() { force_ipv4_unsupported_for_test = old_val; }};
+  bool old_val = force_ipv4_unsupported_for_test.load();
+  force_ipv4_unsupported_for_test.store(new_val);
+  return {[old_val]() { force_ipv4_unsupported_for_test.store(old_val); }};
 }
 
 absl::Status Ipv4Instance::validateProtocolSupported() {
   static const bool supported = SocketInterfaceSingleton::get().ipFamilySupported(AF_INET);
-  if (supported && !force_ipv4_unsupported_for_test) {
+  if (supported && !force_ipv4_unsupported_for_test.load(std::memory_order_relaxed)) {
     return absl::OkStatus();
   }
   return absl::FailedPreconditionError("IPv4 addresses are not supported on this machine");
@@ -335,18 +335,18 @@ Ipv6Instance::Ipv6Instance(absl::Status& status, const sockaddr_in6& address, bo
 }
 
 namespace {
-bool force_ipv6_unsupported_for_test = false;
+std::atomic<bool> force_ipv6_unsupported_for_test = false;
 }
 
 Cleanup Ipv6Instance::forceProtocolUnsupportedForTest(bool new_val) {
-  bool old_val = force_ipv6_unsupported_for_test;
-  force_ipv6_unsupported_for_test = new_val;
-  return {[old_val]() { force_ipv6_unsupported_for_test = old_val; }};
+  bool old_val = force_ipv6_unsupported_for_test.load();
+  force_ipv6_unsupported_for_test.store(new_val);
+  return {[old_val]() { force_ipv6_unsupported_for_test.store(old_val); }};
 }
 
 absl::Status Ipv6Instance::validateProtocolSupported() {
   static const bool supported = SocketInterfaceSingleton::get().ipFamilySupported(AF_INET6);
-  if (supported && !force_ipv6_unsupported_for_test) {
+  if (supported && !force_ipv6_unsupported_for_test.load(std::memory_order_relaxed)) {
     return absl::OkStatus();
   }
   return absl::FailedPreconditionError("IPv6 addresses are not supported on this machine");