From 2ebdb61620995a67b110526dfd1e0b6c3d5f6b11 Mon Sep 17 00:00:00 2001
From: Bowgo Tsai <bowgotsai@google.com>
Date: Thu, 15 Jul 2021 09:46:53 +0000
Subject: [PATCH] Revert "bionic_systrace: moving global static variables"

This reverts commit 1e1c7845aab0542306f61d8e8c880aca096ea336.

Reason for revert: makes property get/set non-reentrant

Bug: 193050299
Test: build and boot a device
Change-Id: If59e3dc25684a3c2b1d3ff74f995311afe6c6e89
Merged-In: If59e3dc25684a3c2b1d3ff74f995311afe6c6e89
(cherry picked from commit 3ec21f527acbaefb5f7a114125bc7a93baa780c7)
---
 libc/bionic/bionic_systrace.cpp | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/libc/bionic/bionic_systrace.cpp b/libc/bionic/bionic_systrace.cpp
index 0de51c50a..06f450514 100644
--- a/libc/bionic/bionic_systrace.cpp
+++ b/libc/bionic/bionic_systrace.cpp
@@ -31,29 +31,33 @@
 #define WRITE_OFFSET   32
 
 static Lock g_lock;
+static uint64_t g_tags;
+static int g_trace_marker_fd = -1;
+
+static CachedProperty& GetTagsProp() {
+  static CachedProperty cached_property(kTraceTagsProp);
+  return cached_property;
+}
 
 bool should_trace(const uint64_t enable_tags) {
-  static uint64_t tags_val;
-  static CachedProperty tags_prop(kTraceTagsProp);
   g_lock.lock();
-  if (tags_prop.DidChange()) {
-    tags_val = strtoull(tags_prop.Get(), nullptr, 0);
+  if (GetTagsProp().DidChange()) {
+    g_tags = strtoull(GetTagsProp().Get(), nullptr, 0);
   }
   g_lock.unlock();
-  return tags_val & enable_tags;
+  return g_tags & enable_tags;
 }
 
 int get_trace_marker_fd() {
-  static int opened_trace_marker_fd = -1;
   g_lock.lock();
-  if (opened_trace_marker_fd == -1) {
-    opened_trace_marker_fd = open("/sys/kernel/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
-    if (opened_trace_marker_fd == -1) {
-      opened_trace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
+  if (g_trace_marker_fd == -1) {
+    g_trace_marker_fd = open("/sys/kernel/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
+    if (g_trace_marker_fd == -1) {
+      g_trace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
     }
   }
   g_lock.unlock();
-  return opened_trace_marker_fd;
+  return g_trace_marker_fd;
 }
 
 // event could be 'B' for begin or 'E' for end.