Vulkan: Work-around Android start-up race condition

Work-around a race condition during Android start-up, while the
`service.sf.present_timestamp` property is asynchronously working its
way from HWC to other processes (especially render engine).  This can
cause the two successive calls to EnumerateDeviceExtensionProperties
to have different numbers of extensions.  That causes the second call
to return VK_INCOMPLETE, which can cause vkCreateDevice() to fail.
The work-around is to add 1 to the "count" returned by the first call.

Test: Manual test with additional logging
Bug: b/206733351
Change-Id: I7b29998d670196d2af772f19be30b2e9498acfe0

1 files changed, 7 insertions, 0 deletions

diff --git a/vulkan/libvulkan/api.cpp b/vulkan/libvulkan/api.cpp
index d1cd397da4..fa3b2601a4 100644
--- a/vulkan/libvulkan/api.cpp
+++ b/vulkan/libvulkan/api.cpp
@@ -965,6 +965,13 @@ VkResult LayerChain::ValidateExtensions(VkPhysicalDevice physical_dev,
     VkResult result = EnumerateDeviceExtensionProperties(physical_dev, nullptr,
                                                          &count, nullptr);
     if (result == VK_SUCCESS && count) {
+        // Work-around a race condition during Android start-up, that can result
+        // in the second call to EnumerateDeviceExtensionProperties having
+        // another extension.  That causes the second call to return
+        // VK_INCOMPLETE.  A work-around is to add 1 to "count" and ask for one
+        // more extension property.  See: http://anglebug.com/6715 and
+        // internal-to-Google b/206733351.
+        count++;
         driver_extensions_ = AllocateDriverExtensionArray(count);
         result = (driver_extensions_)
                      ? EnumerateDeviceExtensionProperties(