From fdafb3d0ec67b40894ce0dd597d3142cc98ab943 Mon Sep 17 00:00:00 2001
From: Wei Wang <wvw@google.com>
Date: Fri, 8 Jun 2018 00:34:44 -0700
Subject: [PATCH] init: Add warning in init first stage mount

init need find required devices and it some times takes a long time due
to rogue drivers. Add a warning if the timing is longer than 50ms.

Bug: 80494921
Test: Reboot
Change-Id: I8f937d7ca7127dc89ed76bb6e5f1781459d5c94a
---
 init/uevent_listener.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/init/uevent_listener.cpp b/init/uevent_listener.cpp
index 24b14c44d..81486e108 100644
--- a/init/uevent_listener.cpp
+++ b/init/uevent_listener.cpp
@@ -23,7 +23,11 @@
 
 #include <memory>
 
+#include <android-base/chrono_utils.h>
+#include <android-base/file.h>
 #include <android-base/logging.h>
+#include <android-base/scopeguard.h>
+#include <android-base/stringprintf.h>
 #include <cutils/uevent.h>
 
 namespace android {
@@ -130,9 +134,19 @@ ListenerAction UeventListener::RegenerateUeventsForDir(DIR* d,
 
     int fd = openat(dfd, "uevent", O_WRONLY);
     if (fd >= 0) {
+        android::base::Timer t;
         write(fd, "add\n", 4);
+        const std::string fd_path = android::base::StringPrintf("/proc/self/fd/%d", fd);
+        std::string uevent_file_path;
+        android::base::Readlink(fd_path, &uevent_file_path);
         close(fd);
 
+        auto guard = android::base::make_scope_guard([&t, &uevent_file_path]() {
+            if (t.duration() > 50ms) {
+                LOG(WARNING) << "ReadUevent took " << t << " on '" << uevent_file_path << "'";
+            }
+        });
+
         Uevent uevent;
         while (ReadUevent(&uevent)) {
             if (callback(uevent) == ListenerAction::kStop) return ListenerAction::kStop;