96 lines
3.1 KiB
C++
96 lines
3.1 KiB
C++
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <sys/uio.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <atomic>
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#include <string>
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#include "gtest/gtest.h"
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#include "absl/time/clock.h"
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#include "absl/time/time.h"
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#include "test/util/file_descriptor.h"
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#include "test/util/logging.h"
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#include "test/util/memory_util.h"
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#include "test/util/temp_path.h"
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#include "test/util/test_util.h"
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#include "test/util/thread_util.h"
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#include "test/util/timer_util.h"
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namespace gvisor {
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namespace testing {
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namespace {
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// Stress copy-on-write. Attempts to reproduce b/38430174.
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TEST(PreadvTest, MMConcurrencyStress) {
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// Fill a one-page file with zeroes (the contents don't really matter).
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const auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
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/* parent = */ GetAbsoluteTestTmpdir(),
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/* content = */ std::string(kPageSize, 0), TempPath::kDefaultFileMode));
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const FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDONLY));
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// Get a one-page private mapping to read to.
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const Mapping m = ASSERT_NO_ERRNO_AND_VALUE(
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MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE));
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// Repeatedly fork in a separate thread to force the mapping to become
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// copy-on-write.
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std::atomic<bool> done(false);
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const ScopedThread t([&] {
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while (!done.load()) {
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const pid_t pid = fork();
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TEST_CHECK(pid >= 0);
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if (pid == 0) {
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// In child. The parent was obviously multithreaded, so it's neither
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// safe nor necessary to do much more than exit.
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syscall(SYS_exit_group, 0);
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}
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int status;
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ASSERT_THAT(RetryEINTR(waitpid)(pid, &status, 0),
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SyscallSucceedsWithValue(pid));
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EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0)
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<< "status = " << status;
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}
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});
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// Repeatedly read to the mapping.
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struct iovec iov[2];
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iov[0].iov_base = m.ptr();
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iov[0].iov_len = kPageSize / 2;
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iov[1].iov_base = reinterpret_cast<void*>(m.addr() + kPageSize / 2);
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iov[1].iov_len = kPageSize / 2;
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constexpr absl::Duration kTestDuration = absl::Seconds(5);
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const absl::Time end = absl::Now() + kTestDuration;
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while (absl::Now() < end) {
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// Among other causes, save/restore cycles may cause interruptions resulting
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// in partial reads, so we don't expect any particular return value.
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EXPECT_THAT(RetryEINTR(preadv)(fd.get(), iov, 2, 0), SyscallSucceeds());
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}
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// Stop the other thread.
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done.store(true);
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// The test passes if it neither deadlocks nor crashes the OS.
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}
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} // namespace
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} // namespace testing
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} // namespace gvisor
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