commit 150687b87d61cf3f07083a77b0fee38f21a84c68
author Mark Salyzyn <salyzyn@google.com> Tue May 12 18:13:14 2020 -0700
committer Mark Salyzyn <salyzyn@google.com> Wed May 13 17:56:31 2020 -0700
tree 2d574c7348afbd2ea58c7c0d8d636cc38dee30f5
parent 5133bbfd3412cb2dc30d07149736ad1ec5779979

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

diff --git a/init/init.cpp b/init/init.cpp
index 3f8f628..631db8e 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -537,7 +537,9 @@
 // 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 @@
         if (dp->d_name[0] == '.') continue;
 
         SetProperty("sys.usb.controller", dp->d_name);
+        controller_set = true;
         break;
     }
 }
@@ -800,7 +803,7 @@
     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 @@
         }
         if (!IsShuttingDown()) {
             HandleControlMessages();
+            SetUsbController();
         }
     }