EGL: deallocate TLS data on thread termination
Test: ad-hoc test using getrusage/ru_maxrss
(any test based on maxrss is too flaky for automation)
Bug: 94039904
Change-Id: I03e0d93df03d36517e407784352050c3dab95bda
diff --git a/opengl/libs/EGL/egl_tls.cpp b/opengl/libs/EGL/egl_tls.cpp
index 8508c5f..297a8a3 100644
--- a/opengl/libs/EGL/egl_tls.cpp
+++ b/opengl/libs/EGL/egl_tls.cpp
@@ -55,13 +55,38 @@
void egl_tls_t::validateTLSKey()
{
struct TlsKeyInitializer {
- static void create() {
- pthread_key_create(&sKey, (void (*)(void*))&eglReleaseThread);
- }
+ static void create() { pthread_key_create(&sKey, destructTLSData); }
};
pthread_once(&sOnceKey, TlsKeyInitializer::create);
}
+void egl_tls_t::destructTLSData(void* data) {
+ egl_tls_t* tls = static_cast<egl_tls_t*>(data);
+ if (!tls) return;
+
+ // Several things in the call tree of eglReleaseThread expect to be able to get the current
+ // thread state directly from TLS. That's a problem because Bionic has already cleared our
+ // TLS pointer before calling this function (pthread_getspecific(sKey) will return nullptr).
+ // Instead the data is passed as our parameter.
+ //
+ // Ideally we'd refactor this so we have thin wrappers that retrieve thread state from TLS and
+ // then pass it as a parameter (or 'this' pointer) to functions that do the real work without
+ // touching TLS. Then from here we could just call those implementation functions with the the
+ // TLS data we just received as a parameter.
+ //
+ // But that's a fairly invasive refactoring, so to do this robustly in the short term we just
+ // put the data *back* in TLS and call the top-level eglReleaseThread. It and it's call tree
+ // will retrieve the value from TLS, and then finally clear the TLS data. Bionic explicitly
+ // tolerates re-setting the value that it's currently trying to destruct (see
+ // pthread_key_clean_all()). Even if we forgot to clear the restored TLS data, bionic would
+ // call the destructor again, but eventually gives up and just leaks the data rather than
+ // enter an infinite loop.
+ pthread_setspecific(sKey, tls);
+ eglReleaseThread();
+ ALOGE_IF(pthread_getspecific(sKey) != nullptr,
+ "EGL TLS data still exists after eglReleaseThread");
+}
+
void egl_tls_t::setErrorEtcImpl(
const char* caller, int line, EGLint error, bool quiet) {
validateTLSKey();