From 150687b87d61cf3f07083a77b0fee38f21a84c68 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Tue, 12 May 2020 18:13:14 -0700
Subject: [PATCH] init: failed to set sys.usb.controller

With GKI we find in certain situations the timing of the drivers
loading is delayed as compared to a monolithic kernel.  This
introduces a race where during second stage init, the attributes
inside /sys/class/udc/ might not be set by the time
SetUsbController() is called.

To address this, we also call SetUsbController() until the property
sys.usb.controller is set at the bottom of the event loop.

Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 151950334
Test: make sure user space fastbootd comes up reliably for a GKI kernel
Change-Id: Iececd8ffa3e6641554d215d622d8dab72d85d34d
---
 init/init.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/init/init.cpp b/init/init.cpp
index 3f8f6281c..631db8e7f 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -537,7 +537,9 @@ static Result<void> queue_property_triggers_action(const BuiltinArguments& args)
 // Set the UDC controller for the ConfigFS USB Gadgets.
 // Read the UDC controller in use from "/sys/class/udc".
 // In case of multiple UDC controllers select the first one.
-static void set_usb_controller() {
+static void SetUsbController() {
+    static auto controller_set = false;
+    if (controller_set) return;
     std::unique_ptr<DIR, decltype(&closedir)>dir(opendir("/sys/class/udc"), closedir);
     if (!dir) return;
 
@@ -546,6 +548,7 @@ static void set_usb_controller() {
         if (dp->d_name[0] == '.') continue;
 
         SetProperty("sys.usb.controller", dp->d_name);
+        controller_set = true;
         break;
     }
 }
@@ -800,7 +803,7 @@ int SecondStageMain(int argc, char** argv) {
     fs_mgr_vendor_overlay_mount_all();
     export_oem_lock_status();
     MountHandler mount_handler(&epoll);
-    set_usb_controller();
+    SetUsbController();
 
     const BuiltinFunctionMap& function_map = GetBuiltinFunctionMap();
     Action::set_function_map(&function_map);
@@ -910,6 +913,7 @@ int SecondStageMain(int argc, char** argv) {
         }
         if (!IsShuttingDown()) {
             HandleControlMessages();
+            SetUsbController();
         }
     }