commit e184423526888dade9c672ea2584127ae1d9d949
author Paul Crowley <paulcrowley@google.com> Mon Jan 29 15:47:14 2018 -0800
committer Paul Crowley <paulcrowley@google.com> Tue Jan 30 08:18:24 2018 -0800
tree 69953a95622f7ac6e09d8a05978387109fa15958
parent 01ba1157325a5e6572122f5d46cfd0376b75aa98

Don't initialize atrace if it's already disabled.

For processes that start very early, atrace initialization can cause
an selinux denial, so make sure it's possible to disable it and avoid
the call to open "trace_marker".

Bug: 63927601
Test: disable atrace early in vold, ensure that selinux denial is
avoided.

Change-Id: I2422e6d0db323bc13c6d6ed1896435151fca21f7

libcutils/trace-dev.cpp

diff --git a/libcutils/trace-dev.cpp b/libcutils/trace-dev.cpp
index 4da8215..27255c2 100644
--- a/libcutils/trace-dev.cpp
+++ b/libcutils/trace-dev.cpp
@@ -25,6 +25,7 @@
 void atrace_set_tracing_enabled(bool enabled)
 {
     atomic_store_explicit(&atrace_is_enabled, enabled, memory_order_release);
+    atomic_store_explicit(&atrace_is_ready, false, memory_order_release);
     atrace_update_tags();
 }
 
@@ -34,18 +35,17 @@
     if (atrace_marker_fd == -1) {
         ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno);
         atrace_enabled_tags = 0;
-        goto done;
+        return;
     }
-
     atrace_enabled_tags = atrace_get_property();
-
-done:
-    atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
 }
 
 void atrace_setup()
 {
-    pthread_once(&atrace_once_control, atrace_init_once);
+    if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
+        pthread_once(&atrace_once_control, atrace_init_once);
+    }
+    atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
 }
 
 void atrace_begin_body(const char* name)