From 2d613f8e3002ef4f62b8029ba56861d73211feeb Mon Sep 17 00:00:00 2001
From: Ian Gudger <igudger@google.com>
Date: Mon, 4 Mar 2019 13:03:50 -0800
Subject: Deflake socket_ipv4_udp_unbound_loopback.

When run in parallel, multicast packets can be received by the wrong test. The
tests in the target are run in an isolated network namespace, but if
parallelism is enabled, multiple tests from the same target will run in
parallel within the target's network namespace. Disabling parallelism only
allows one test to run in the network namespace at a time, which prevents
interaction.

PiperOrigin-RevId: 236709160
Change-Id: If828db44f0ae4002af36de6097866137c8d9da5c
---
 test/syscalls/BUILD          |  4 ++--
 test/syscalls/build_defs.bzl | 28 +++++++++++++++++++---------
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/test/syscalls/BUILD b/test/syscalls/BUILD
index 39f1de0c9..a8fd20956 100644
--- a/test/syscalls/BUILD
+++ b/test/syscalls/BUILD
@@ -364,8 +364,8 @@ syscall_test(
 )
 
 syscall_test(
-    # FIXME
-    tags = ["flaky"],
+    # Multicast packets can be received by the wrong test if run in parallel.
+    parallel = False,
     test = "//test/syscalls/linux:socket_ipv4_udp_unbound_loopback_test",
 )
 
diff --git a/test/syscalls/build_defs.bzl b/test/syscalls/build_defs.bzl
index 88777f55b..610b030b2 100644
--- a/test/syscalls/build_defs.bzl
+++ b/test/syscalls/build_defs.bzl
@@ -7,7 +7,8 @@ def syscall_test(
         shard_count = 1,
         size = "small",
         use_tmpfs = False,
-        tags = None):
+        tags = None,
+        parallel = True):
     _syscall_test(
         test = test,
         shard_count = shard_count,
@@ -15,6 +16,7 @@ def syscall_test(
         platform = "native",
         use_tmpfs = False,
         tags = tags,
+        parallel = parallel,
     )
 
     _syscall_test(
@@ -24,6 +26,7 @@ def syscall_test(
         platform = "kvm",
         use_tmpfs = use_tmpfs,
         tags = tags,
+        parallel = parallel,
     )
 
     _syscall_test(
@@ -33,6 +36,7 @@ def syscall_test(
         platform = "ptrace",
         use_tmpfs = use_tmpfs,
         tags = tags,
+        parallel = parallel,
     )
 
     if not use_tmpfs:
@@ -44,6 +48,7 @@ def syscall_test(
             platform = "ptrace",
             use_tmpfs = use_tmpfs,
             tags = tags,
+            parallel = parallel,
             file_access = "shared",
         )
 
@@ -54,6 +59,7 @@ def _syscall_test(
         platform,
         use_tmpfs,
         tags,
+        parallel,
         file_access = "exclusive"):
     test_name = test.split(":")[1]
 
@@ -80,6 +86,17 @@ def _syscall_test(
     if platform == "kvm":
         tags += ["manual"]
 
+    args = [
+        # Arguments are passed directly to syscall_test_runner binary.
+        "--test-name=" + test_name,
+        "--platform=" + platform,
+        "--use-tmpfs=" + str(use_tmpfs),
+        "--file-access=" + file_access,
+    ]
+
+    if parallel:
+        args += ["--parallel=true"]
+
     sh_test(
         srcs = ["syscall_test_runner.sh"],
         name = name,
@@ -87,14 +104,7 @@ def _syscall_test(
             ":syscall_test_runner",
             test,
         ],
-        args = [
-            # Arguments are passed directly to syscall_test_runner binary.
-            "--test-name=" + test_name,
-            "--platform=" + platform,
-            "--use-tmpfs=" + str(use_tmpfs),
-            "--file-access=" + file_access,
-            "--parallel=true",
-        ],
+        args = args,
         size = size,
         tags = tags,
         shard_count = shard_count,
-- 
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