Added a test to catch such things in future

2 files changed, 133 insertions, 3 deletions

diff --git a/test/core/iomgr/BUILD b/test/core/iomgr/BUILD
index bbf0815e6f..cc1b6aee5e 100644
--- a/test/core/iomgr/BUILD
+++ b/test/core/iomgr/BUILD
@@ -18,7 +18,10 @@ licenses(["notice"])  # Apache v2
 
 load("//test/core/util:grpc_fuzzer.bzl", "grpc_fuzzer")
 
-grpc_package(name = "test/core/iomgr", visibility = "public") # Useful for third party devs to test their io manager implementation.
+grpc_package(
+    name = "test/core/iomgr",
+    visibility = "public",
+)  # Useful for third party devs to test their io manager implementation.
 
 grpc_cc_library(
     name = "endpoint_tests",
@@ -73,15 +76,27 @@ grpc_cc_test(
 )
 
 grpc_cc_test(
+    name = "ev_epollex_linux_test",
+    srcs = ["ev_epollex_linux_test.cc"],
+    language = "C++",
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//test/core/util:gpr_test_util",
+        "//test/core/util:grpc_test_util",
+    ],
+)
+
+grpc_cc_test(
     name = "ev_epollsig_linux_test",
     srcs = ["ev_epollsig_linux_test.cc"],
+    language = "C++",
     deps = [
         "//:gpr",
         "//:grpc",
         "//test/core/util:gpr_test_util",
         "//test/core/util:grpc_test_util",
     ],
-    language = "C++",
 )
 
 grpc_cc_test(
@@ -221,13 +236,13 @@ grpc_cc_test(
     name = "tcp_server_posix_test",
     srcs = ["tcp_server_posix_test.cc"],
     language = "C++",
+    tags = ["manual"],  # TODO(adelez): Remove once this works on Foundry.
     deps = [
         "//:gpr",
         "//:grpc",
         "//test/core/util:gpr_test_util",
         "//test/core/util:grpc_test_util",
     ],
-    tags = ["manual"],    # TODO(adelez): Remove once this works on Foundry.
 )
 
 grpc_cc_test(
diff --git a/test/core/iomgr/ev_epollex_linux_test.cc b/test/core/iomgr/ev_epollex_linux_test.cc
new file mode 100644
index 0000000000..08d1e68b39
--- /dev/null
+++ b/test/core/iomgr/ev_epollex_linux_test.cc
@@ -0,0 +1,115 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+#include "src/core/lib/iomgr/port.h"
+
+/* This test only relevant on linux systems where epoll() is available */
+#if defined(GRPC_LINUX_EPOLL_CREATE1) && defined(GRPC_LINUX_EVENTFD)
+#include "src/core/lib/iomgr/ev_epollex_linux.h"
+
+#include <grpc/grpc.h>
+#include <string.h>
+#include <sys/eventfd.h>
+
+#include "test/core/util/test_config.h"
+
+static void pollset_destroy(void* ps, grpc_error* error) {
+  grpc_pollset_destroy(static_cast<grpc_pollset*>(ps));
+  gpr_free(ps);
+}
+
+// This test is added to cover the case found in bug:
+// https://github.com/grpc/grpc/issues/15760
+static void test_pollable_owner_fd() {
+  grpc_core::ExecCtx exec_ctx;
+  int ev_fd1;
+  int ev_fd2;
+  grpc_fd* grpc_fd1;
+  grpc_fd* grpc_fd2;
+  grpc_pollset* ps;
+  gpr_mu* mu;
+
+  // == Create two grpc_fds ==
+  // All we need is two file descriptors. Doesn't matter what type. We use
+  // eventfd type here for the purpose of this test
+  ev_fd1 = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+  ev_fd2 = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+  if (ev_fd1 < 0 || ev_fd2 < 0) {
+    gpr_log(GPR_ERROR, "Error in creating event fds for the test");
+    return;
+  }
+  grpc_fd1 = grpc_fd_create(ev_fd1, "epollex-test-fd1", false);
+  grpc_fd2 = grpc_fd_create(ev_fd2, "epollex-test-fd2", false);
+  grpc_core::ExecCtx::Get()->Flush();
+
+  // == Create a pollset ==
+  ps = static_cast<grpc_pollset*>(gpr_zalloc(grpc_pollset_size()));
+  grpc_pollset_init(ps, &mu);
+  grpc_core::ExecCtx::Get()->Flush();
+
+  // == Add fd1 to pollset ==
+  grpc_pollset_add_fd(ps, grpc_fd1);
+  grpc_core::ExecCtx::Get()->Flush();
+
+  // == Destroy fd1 ==
+  grpc_fd_orphan(grpc_fd1, nullptr, nullptr, "test fd1 orphan");
+  grpc_core::ExecCtx::Get()->Flush();
+
+  // = Add fd2 to pollset ==
+  //
+  // Before https://github.com/grpc/grpc/issues/15760, the following line caused
+  // unexpected behavior (The previous grpc_pollset_add_fd(ps, grpc_fd1) created
+  // an underlying structure in epollex that held a reference to grpc_fd1 which
+  // was being accessed here even after grpc_fd_orphan(grpc_fd1) was called
+  grpc_pollset_add_fd(ps, grpc_fd2);
+  grpc_core::ExecCtx::Get()->Flush();
+
+  // == Destroy fd2 ==
+  grpc_fd_orphan(grpc_fd2, nullptr, nullptr, "test fd2 orphan");
+  grpc_core::ExecCtx::Get()->Flush();
+
+  // == Destroy pollset
+  grpc_closure ps_destroy_closure;
+  GRPC_CLOSURE_INIT(&ps_destroy_closure, pollset_destroy, ps,
+                    grpc_schedule_on_exec_ctx);
+  grpc_pollset_shutdown(ps, &ps_destroy_closure);
+  grpc_core::ExecCtx::Get()->Flush();
+}
+
+int main(int argc, char** argv) {
+  const char* poll_strategy = nullptr;
+  grpc_test_init(argc, argv);
+  grpc_init();
+  {
+    grpc_core::ExecCtx exec_ctx;
+    poll_strategy = grpc_get_poll_strategy_name();
+    if (poll_strategy != nullptr && strcmp(poll_strategy, "epollex") == 0) {
+      test_pollable_owner_fd();
+    } else {
+      gpr_log(GPR_INFO,
+              "Skipping the test. The test is only relevant for 'epollex' "
+              "strategy. and the current strategy is: '%s'",
+              poll_strategy);
+    }
+  }
+
+  grpc_shutdown();
+  return 0;
+}
+#else /* defined(GRPC_LINUX_EPOLL_CREATE1) && defined(GRPC_LINUX_EVENTFD) */
+int main(int argc, char** argv) { return 0; }
+#endif