Vulkan: unload builtin driver to reload updated driver if needed

Android historically preloads GL driver in Zygote to speed up app launch
time and avoid the duplicate extra memory for each process loading the
graphics driver. In Android 10, we landed GL driver unloading mechanism
to ship updatable driver and ANGLE without perf overhead on the rest of
the system.

To get prepared for the HWUI Vulkan backend being turned on as the
default renderer for UI componments, this CL will do the same to the
Vulkan driver to preload it in Zygote and unload so to reload updated
driver if needed.

Bug: 135536511
Test: atest CtsUiRenderingTestCases no regression on VK backend
Change-Id: I2909f6ecc4f011b1f3670aacdf817ed3b6e9a487

1 files changed, 40 insertions, 1 deletions

diff --git a/vulkan/libvulkan/driver.cpp b/vulkan/libvulkan/driver.cpp
index e3fc67e35f..8deca47c66 100644
--- a/vulkan/libvulkan/driver.cpp
+++ b/vulkan/libvulkan/driver.cpp
@@ -84,6 +84,8 @@ class Hal {
     Hal(const Hal&) = delete;
     Hal& operator=(const Hal&) = delete;
 
+    bool ShouldUnloadBuiltinDriver();
+    void UnloadBuiltinDriver();
     bool InitDebugReportIndex();
 
     static Hal hal_;
@@ -243,7 +245,12 @@ bool Hal::Open() {
 
     const nsecs_t openTime = systemTime();
 
-    ALOG_ASSERT(!hal_.dev_, "OpenHAL called more than once");
+    if (hal_.ShouldUnloadBuiltinDriver()) {
+        hal_.UnloadBuiltinDriver();
+    }
+
+    if (hal_.dev_)
+        return true;
 
     // Use a stub device unless we successfully open a real HAL device.
     hal_.dev_ = &stubhal::kDevice;
@@ -288,6 +295,38 @@ bool Hal::Open() {
     return true;
 }
 
+bool Hal::ShouldUnloadBuiltinDriver() {
+    // Should not unload since the driver was not loaded
+    if (!hal_.dev_)
+        return false;
+
+    // Should not unload if stubhal is used on the device
+    if (hal_.dev_ == &stubhal::kDevice)
+        return false;
+
+    // Unload the driver if updated driver is chosen
+    if (android::GraphicsEnv::getInstance().getDriverNamespace())
+        return true;
+
+    return false;
+}
+
+void Hal::UnloadBuiltinDriver() {
+    ATRACE_CALL();
+
+    ALOGD("Unload builtin Vulkan driver.");
+
+    // Close the opened device
+    ALOG_ASSERT(!hal_.dev_->common.close(hal_.dev_->common),
+                "hw_device_t::close() failed.");
+
+    // Close the opened shared library in the hw_module_t
+    dlclose(hal_.dev_->common.module->dso);
+
+    hal_.dev_ = nullptr;
+    hal_.debug_report_index_ = -1;
+}
+
 bool Hal::InitDebugReportIndex() {
     ATRACE_CALL();