commit 379571098d1b597a2a5f159dfc7522cc4fde6c63
author Tianjie Xu <xunchang@google.com> Wed Jun 07 17:59:55 2017 -0700
committer Tianjie Xu <xunchang@google.com> Thu Jun 08 12:10:30 2017 -0700
tree a7bbca448c95438c9832fb8067feecd8c4197508
parent 99e7216907e55ec6895e445190bb361fcfd437a7

Fix a race condition for temperature_logger

It's a rare deadlock that happens on fugu when the updater exits too
fast due to a format error.

Bug: 62379170
Test: fake-ota fails gracefully without hanging.
Change-Id: Icbd6cff4f6b44ca20f4d75f8039332111f696cc5

install.cpp

diff --git a/install.cpp b/install.cpp
index a1f2e4f..db4ba93 100644
--- a/install.cpp
+++ b/install.cpp
@@ -27,6 +27,7 @@
 #include <unistd.h>
 
 #include <algorithm>
+#include <atomic>
 #include <chrono>
 #include <condition_variable>
 #include <functional>
@@ -294,11 +295,12 @@
 }
 #endif  // !AB_OTA_UPDATER
 
-static void log_max_temperature(int* max_temperature) {
+static void log_max_temperature(int* max_temperature, const std::atomic<bool>& logger_finished) {
   CHECK(max_temperature != nullptr);
   std::mutex mtx;
   std::unique_lock<std::mutex> lck(mtx);
-  while (finish_log_temperature.wait_for(lck, 20s) == std::cv_status::timeout) {
+  while (!logger_finished.load() &&
+         finish_log_temperature.wait_for(lck, 20s) == std::cv_status::timeout) {
     *max_temperature = std::max(*max_temperature, GetMaxValueFromThermalZone());
   }
 }
@@ -403,7 +405,8 @@
   }
   close(pipefd[1]);
 
-  std::thread temperature_logger(log_max_temperature, max_temperature);
+  std::atomic<bool> logger_finished(false);
+  std::thread temperature_logger(log_max_temperature, max_temperature, std::ref(logger_finished));
 
   *wipe_cache = false;
   bool retry_update = false;
@@ -467,6 +470,7 @@
   int status;
   waitpid(pid, &status, 0);
 
+  logger_finished.store(true);
   finish_log_temperature.notify_one();
   temperature_logger.join();