1 files changed, 23 insertions, 30 deletions

diff --git a/libc/bionic/bionic_systrace.cpp b/libc/bionic/bionic_systrace.cpp
index 0de51c50a..fd9771298 100644
--- a/libc/bionic/bionic_systrace.cpp
+++ b/libc/bionic/bionic_systrace.cpp
@@ -14,50 +14,52 @@
  * limitations under the License.
  */
 
-#include "private/bionic_systrace.h"
-
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include "private/bionic_lock.h"
+#include "private/bionic_systrace.h"
+#include "private/CachedProperty.h"
+
 #include <async_safe/log.h>
 #include <cutils/trace.h> // For ATRACE_TAG_BIONIC.
 
-#include "private/CachedProperty.h"
-#include "private/bionic_lock.h"
-
 #define WRITE_OFFSET   32
 
 static Lock g_lock;
+static CachedProperty g_debug_atrace_tags_enableflags("debug.atrace.tags.enableflags");
+static uint64_t g_tags;
+static int g_trace_marker_fd = -1;
 
-bool should_trace(const uint64_t enable_tags) {
-  static uint64_t tags_val;
-  static CachedProperty tags_prop(kTraceTagsProp);
+static bool should_trace() {
   g_lock.lock();
-  if (tags_prop.DidChange()) {
-    tags_val = strtoull(tags_prop.Get(), nullptr, 0);
+  if (g_debug_atrace_tags_enableflags.DidChange()) {
+    g_tags = strtoull(g_debug_atrace_tags_enableflags.Get(), nullptr, 0);
   }
   g_lock.unlock();
-  return tags_val & enable_tags;
+  return ((g_tags & ATRACE_TAG_BIONIC) != 0);
 }
 
-int get_trace_marker_fd() {
-  static int opened_trace_marker_fd = -1;
+static int get_trace_marker_fd() {
   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.
-void output_trace(const char* message, const char event) {
+void bionic_trace_begin(const char* message) {
+  if (!should_trace()) {
+    return;
+  }
+
   int trace_marker_fd = get_trace_marker_fd();
   if (trace_marker_fd == -1) {
     return;
@@ -67,22 +69,13 @@ void output_trace(const char* message, const char event) {
   // kernel trace_marker.
   int length = strlen(message);
   char buf[length + WRITE_OFFSET];
-  size_t len =
-      async_safe_format_buffer(buf, length + WRITE_OFFSET, "%c|%d|%s", event, getpid(), message);
+  size_t len = async_safe_format_buffer(buf, length + WRITE_OFFSET, "B|%d|%s", getpid(), message);
 
   // Tracing may stop just after checking property and before writing the message.
   // So the write is acceptable to fail. See b/20666100.
   TEMP_FAILURE_RETRY(write(trace_marker_fd, buf, len));
 }
 
-void bionic_trace_begin(const char* message) {
-  if (!should_trace()) {
-    return;
-  }
-
-  output_trace(message);
-}
-
 void bionic_trace_end() {
   if (!should_trace()) {
     return;