From ca8dce919c45d30621ad7c776cba6370301ed890 Mon Sep 17 00:00:00 2001
From: Yiwei Zhang <zzyiwei@google.com>
Date: Tue, 27 Aug 2019 00:27:29 -0700
Subject: opengl: fix a race condition when unloading gl driver

Previously, EGL apis call clearError() at the first place including those core
apis which initialize the driver. Calling clearError() before the driver has
been loaded is basically a no-op.

Later the driver unloading mechanism was added to support Angle and updatable
driver with EGL/GL driver still preloaded in Zygote. However, calling
clearError() on another thread races with the driver unloading process. So this
change moves the clearError() calls after the driver has been successfully
unloaded and reloaded, so that the initial core apis will be protected by the
driver loading lock in the loader.

For those non-core apis, they could still be incorrectly called before calling
any of those core apis on another thread when the driver unloading and reloading
is still on going. Since this scenario is supposed to error out anyway, so the
apps need to use EGL apis correctly by themselves.

Bug: 140072978
Test: CtsAngleDeveloperOptionHostTest
Change-Id: Ica5b19edc0dfb0a0910f56c1442eaff63f76b35a
Merged-In: Ica5b19edc0dfb0a0910f56c1442eaff63f76b35a
---
 opengl/libs/EGL/eglApi.cpp | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/opengl/libs/EGL/eglApi.cpp b/opengl/libs/EGL/eglApi.cpp
index 29a966d348..c51a1295e7 100644
--- a/opengl/libs/EGL/eglApi.cpp
+++ b/opengl/libs/EGL/eglApi.cpp
@@ -40,7 +40,6 @@ static inline void clearError() {
 
 EGLDisplay eglGetDisplay(EGLNativeDisplayType display) {
     ATRACE_CALL();
-    clearError();
 
     if (egl_init_drivers() == EGL_FALSE) {
         return setError(EGL_BAD_PARAMETER, EGL_NO_DISPLAY);
@@ -48,6 +47,7 @@ EGLDisplay eglGetDisplay(EGLNativeDisplayType display) {
 
     // Call down the chain, which usually points directly to the impl
     // but may also be routed through layers
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglGetDisplay(display);
 }
@@ -55,7 +55,6 @@ EGLDisplay eglGetDisplay(EGLNativeDisplayType display) {
 EGLDisplay eglGetPlatformDisplay(EGLenum platform, EGLNativeDisplayType display,
                                  const EGLAttrib* attrib_list) {
     ATRACE_CALL();
-    clearError();
 
     if (egl_init_drivers() == EGL_FALSE) {
         return setError(EGL_BAD_PARAMETER, EGL_NO_DISPLAY);
@@ -63,6 +62,7 @@ EGLDisplay eglGetPlatformDisplay(EGLenum platform, EGLNativeDisplayType display,
 
     // Call down the chain, which usually points directly to the impl
     // but may also be routed through layers
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglGetPlatformDisplay(platform, display, attrib_list);
 }
@@ -239,13 +239,12 @@ __eglMustCastToProperFunctionPointerType eglGetProcAddress(const char* procname)
     // in which case we must make sure we've initialized ourselves, this
     // happens the first time egl_get_display() is called.
 
-    clearError();
-
     if (egl_init_drivers() == EGL_FALSE) {
         setError(EGL_BAD_PARAMETER, NULL);
         return nullptr;
     }
 
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglGetProcAddress(procname);
 }
@@ -324,23 +323,21 @@ EGLBoolean eglWaitClient(void) {
 }
 
 EGLBoolean eglBindAPI(EGLenum api) {
-    clearError();
-
     if (egl_init_drivers() == EGL_FALSE) {
         return setError(EGL_BAD_PARAMETER, (EGLBoolean)EGL_FALSE);
     }
 
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglBindAPI(api);
 }
 
 EGLenum eglQueryAPI(void) {
-    clearError();
-
     if (egl_init_drivers() == EGL_FALSE) {
         return setError(EGL_BAD_PARAMETER, (EGLBoolean)EGL_FALSE);
     }
 
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglQueryAPI();
 }
@@ -595,23 +592,21 @@ EGLClientBuffer eglGetNativeClientBufferANDROID(const AHardwareBuffer* buffer) {
 }
 
 EGLuint64NV eglGetSystemTimeFrequencyNV() {
-    clearError();
-
     if (egl_init_drivers() == EGL_FALSE) {
         return setError(EGL_BAD_PARAMETER, (EGLuint64NV)EGL_FALSE);
     }
 
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglGetSystemTimeFrequencyNV();
 }
 
 EGLuint64NV eglGetSystemTimeNV() {
-    clearError();
-
     if (egl_init_drivers() == EGL_FALSE) {
         return setError(EGL_BAD_PARAMETER, (EGLuint64NV)EGL_FALSE);
     }
 
+    clearError();
     egl_connection_t* const cnx = &gEGLImpl;
     return cnx->platform.eglGetSystemTimeNV();
 }
-- 
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