From bbb16022c7d13e9cfc628bf0f3de4b40a3670679 Mon Sep 17 00:00:00 2001
From: Tom Cherry <tomcherry@google.com>
Date: Mon, 9 Mar 2020 12:43:18 -0700
Subject: [PATCH] liblog: minimum_log_priority should be atomic

In case multiple threads try to reference this variable while it is
being set, it should be atomic so that all threads always see a valid
value.

Bug: 150898477
Test: liblog, libbase unit tests
Change-Id: If6c9e291f2471b96a752dc6e76e3e63458b71391
---
 liblog/logger_write.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/liblog/logger_write.cpp b/liblog/logger_write.cpp
index 1b6b0c697..0dbb94f09 100644
--- a/liblog/logger_write.cpp
+++ b/liblog/logger_write.cpp
@@ -27,6 +27,7 @@
 #include <android/set_abort_message.h>
 #endif
 
+#include <atomic>
 #include <shared_mutex>
 
 #include <android-base/errno_restorer.h>
@@ -148,11 +149,9 @@ void __android_log_set_default_tag(const char* tag) {
   GetDefaultTag().assign(tag, 0, LOGGER_ENTRY_MAX_PAYLOAD);
 }
 
-static int minimum_log_priority = ANDROID_LOG_DEFAULT;
+static std::atomic_int minimum_log_priority = ANDROID_LOG_DEFAULT;
 int __android_log_set_minimum_priority(int priority) {
-  int old_minimum_log_priority = minimum_log_priority;
-  minimum_log_priority = priority;
-  return old_minimum_log_priority;
+  return minimum_log_priority.exchange(priority, std::memory_order_relaxed);
 }
 
 int __android_log_get_minimum_priority() {