1 files changed, 94 insertions, 0 deletions
diff --git a/test/syscalls/linux/preadv.cc b/test/syscalls/linux/preadv.cc
new file mode 100644
index 000000000..8d3aed43c
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+++ b/test/syscalls/linux/preadv.cc
@@ -0,0 +1,94 @@
+// Copyright 2018 Google LLC
+//
+// 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 <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <atomic>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "gtest/gtest.h"
+#include "absl/time/clock.h"
+#include "absl/time/time.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/logging.h"
+#include "test/util/memory_util.h"
+#include "test/util/temp_path.h"
+#include "test/util/test_util.h"
+#include "test/util/thread_util.h"
+#include "test/util/timer_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+TEST(PreadvTest, MMConcurrencyStress) {
+  // Fill a one-page file with zeroes (the contents don't really matter).
+  const auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      /* parent = */ GetAbsoluteTestTmpdir(),
+      /* content = */ std::string(kPageSize, 0), TempPath::kDefaultFileMode));
+  const FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDONLY));
+
+  // Get a one-page private mapping to read to.
+  const Mapping m = ASSERT_NO_ERRNO_AND_VALUE(
+      MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE));
+
+  // Repeatedly fork in a separate thread to force the mapping to become
+  // copy-on-write.
+  std::atomic<bool> done(false);
+  const ScopedThread t([&] {
+    while (!done.load()) {
+      const pid_t pid = fork();
+      TEST_CHECK(pid >= 0);
+      if (pid == 0) {
+        // In child. The parent was obviously multithreaded, so it's neither
+        // safe nor necessary to do much more than exit.
+        syscall(SYS_exit_group, 0);
+      }
+      int status;
+      ASSERT_THAT(RetryEINTR(waitpid)(pid, &status, 0),
+                  SyscallSucceedsWithValue(pid));
+      EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0)
+          << "status = " << status;
+    }
+  });
+
+  // Repeatedly read to the mapping.
+  struct iovec iov[2];
+  iov[0].iov_base = m.ptr();
+  iov[0].iov_len = kPageSize / 2;
+  iov[1].iov_base = reinterpret_cast<void*>(m.addr() + kPageSize / 2);
+  iov[1].iov_len = kPageSize / 2;
+  constexpr absl::Duration kTestDuration = absl::Seconds(5);
+  const absl::Time end = absl::Now() + kTestDuration;
+  while (absl::Now() < end) {
+    // Among other causes, save/restore cycles may cause interruptions resulting
+    // in partial reads, so we don't expect any particular return value.
+    EXPECT_THAT(RetryEINTR(preadv)(fd.get(), iov, 2, 0), SyscallSucceeds());
+  }
+
+  // Stop the other thread.
+  done.store(true);
+
+  // The test passes if it neither deadlocks nor crashes the OS.
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor