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Fix pthread_join.

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Let the kernel keep pthread_internal_t::tid updated, including
across forks and for the main thread. This then lets us fix
pthread_join to only return after the thread has really exited.

Also fix the thread attributes of the main thread so we don't
unmap the main thread's stack (which is really owned by the
dynamic linker and contains things like environment variables),
which fixes crashes when joining with an exited main thread
and also fixes problems reported publicly with accessing environment
variables after the main thread exits (for which I've added a new
unit test).

In passing I also fixed a bug where if the clone(2) inside
pthread_create(3) fails, we'd unmap the child's stack and TLS (which
contains the mutex) and then try to unlock the mutex. Boom! It wasn't
until after I'd uploaded the fix for this that I came across a new
public bug reporting this exact failure.

Bug: 8206355
Bug: 11693195
Bug: https://code.google.com/p/android/issues/detail?id=57421
Bug: https://code.google.com/p/android/issues/detail?id=62392
Change-Id: I2af9cf6e8ae510a67256ad93cad891794ed0580b
This commit is contained in:
Elliott Hughes
2013-11-15 17:40:18 -08:00
parent f246c589d6
commit 877ec6d904
22 changed files with 263 additions and 81 deletions
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42
tests/pthread_test.cpp
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@@ -150,22 +150,48 @@ TEST(pthread, pthread_join_self) {
ASSERT_EQ(EDEADLK, pthread_join(pthread_self(), &result));
}
#if __BIONIC__ // For some reason, gtest on bionic can cope with this but gtest on glibc can't.
struct TestBug37410 {
pthread_t main_thread;
pthread_mutex_t mutex;
static void TestBug37410() {
pthread_t t1;
ASSERT_EQ(0, pthread_create(&t1, NULL, JoinFn, reinterpret_cast<void*>(pthread_self())));
pthread_exit(NULL);
}
static void main() {
TestBug37410 data;
data.main_thread = pthread_self();
ASSERT_EQ(0, pthread_mutex_init(&data.mutex, NULL));
ASSERT_EQ(0, pthread_mutex_lock(&data.mutex));
pthread_t t;
ASSERT_EQ(0, pthread_create(&t, NULL, TestBug37410::thread_fn, reinterpret_cast<void*>(&data)));
// Wait for the thread to be running...
ASSERT_EQ(0, pthread_mutex_lock(&data.mutex));
ASSERT_EQ(0, pthread_mutex_unlock(&data.mutex));
// ...and exit.
pthread_exit(NULL);
}
private:
static void* thread_fn(void* arg) {
TestBug37410* data = reinterpret_cast<TestBug37410*>(arg);
// Let the main thread know we're running.
pthread_mutex_unlock(&data->mutex);
// And wait for the main thread to exit.
pthread_join(data->main_thread, NULL);
return NULL;
}
};
// Even though this isn't really a death test, we have to say "DeathTest" here so gtest knows to
// run this test (which exits normally) in its own process.
TEST(pthread_DeathTest, pthread_bug_37410) {
// http://code.google.com/p/android/issues/detail?id=37410
::testing::FLAGS_gtest_death_test_style = "threadsafe";
ASSERT_EXIT(TestBug37410(), ::testing::ExitedWithCode(0), "");
ASSERT_EXIT(TestBug37410::main(), ::testing::ExitedWithCode(0), "");
}
#endif
static void* SignalHandlerFn(void* arg) {
sigset_t wait_set;