Always use shared memory for atrace.

Remove ATRACE_SHMEM macro.

Test: atrace ss
      atrace wm
      sanity check output
Bug: 137366208
Change-Id: I1b42243678b9b9a41db18e2ff8cb3cf7bde874de
Merged-In: I1b42243678b9b9a41db18e2ff8cb3cf7bde874de

libcutils/include/cutils/trace.h

@@ -88,12 +88,6 @@ __BEGIN_DECLS
 #error ATRACE_TAG must be defined to be one of the tags defined in cutils/trace.h
 #endif
 
-// Set this to 0 to revert to the old Binder-based atrace implementation.
-// This is only here in case rollbacks do not apply cleanly.
-// TODO(fmayer): Remove this once we are confident this won't need to be
-// rolled back, no later than 2020-03-01.
-#define ATRACE_SHMEM 1
-
 /**
  * Opens the trace file for writing and reads the property for initial tags.
  * The atrace.tags.enableflags property sets the tags to trace.
@@ -121,15 +115,11 @@ void atrace_set_debuggable(bool debuggable);
  * prevent tracing within the Zygote process.
  */
 void atrace_set_tracing_enabled(bool enabled);
+
 /**
- * If !ATRACE_SHMEM:
- *   Flag indicating whether setup has been completed, initialized to 0.
- *   Nonzero indicates setup has completed.
- *   Note: This does NOT indicate whether or not setup was successful.
- * If ATRACE_SHMEM:
- *   This is always set to false. This forces code that uses an old version
- *   of this header to always call into atrace_setup, in which we call
- *   atrace_init unconditionally.
+ * This is always set to false. This forces code that uses an old version
+ * of this header to always call into atrace_setup, in which we call
+ * atrace_init unconditionally.
  */
 extern atomic_bool atrace_is_ready;
 
@@ -154,28 +144,8 @@ extern int atrace_marker_fd;
 #define ATRACE_INIT() atrace_init()
 #define ATRACE_GET_ENABLED_TAGS() atrace_get_enabled_tags()
 
-#if ATRACE_SHMEM
 void atrace_init();
 uint64_t atrace_get_enabled_tags();
-#else
-static inline void atrace_init()
-{
-    if (CC_UNLIKELY(!atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
-        atrace_setup();
-    }
-}
-
-/**
- * Get the mask of all tags currently enabled.
- * It can be used as a guard condition around more expensive trace calculations.
- * Every trace function calls this, which ensures atrace_init is run.
- */
-static inline uint64_t atrace_get_enabled_tags()
-{
-    atrace_init();
-    return atrace_enabled_tags;
-}
-#endif
 
 /**
  * Test if a given tag is currently enabled.

libcutils/trace-dev.cpp

@@ -41,9 +41,6 @@ static void atrace_init_once()
     } else {
       atrace_enabled_tags = atrace_get_property();
     }
-#if !ATRACE_SHMEM
-    atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
-#endif
 }
 
 static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no) {
@@ -69,11 +66,7 @@ static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no) {
 
 void atrace_setup()
 {
-#if ATRACE_SHMEM
     atrace_init();
-#else
-    pthread_once(&atrace_once_control, atrace_init_once);
-#endif
 }
 
 void atrace_begin_body(const char* name)

libcutils/trace-dev.inc

@@ -71,8 +71,6 @@ alignas(uint64_t) static char empty_pi[96];
 static const prop_info* atrace_property_info = reinterpret_cast<const prop_info*>(empty_pi);
 #endif
 
-#if ATRACE_SHMEM
-
 /**
  * This is called when the sequence number of debug.atrace.tags.enableflags
  * changes and we need to reload the enabled tags.
@@ -96,7 +94,6 @@ uint64_t atrace_get_enabled_tags()
     atrace_init();
     return atrace_enabled_tags;
 }
-#endif
 
 // Set whether this process is debuggable, which determines whether
 // application-level tracing is allowed when the ro.debuggable system property
@@ -186,19 +183,17 @@ static uint64_t atrace_get_property()
 void atrace_update_tags()
 {
     uint64_t tags;
-    if (ATRACE_SHMEM || CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
-        if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
-            tags = atrace_get_property();
-            pthread_mutex_lock(&atrace_tags_mutex);
-            atrace_enabled_tags = tags;
-            pthread_mutex_unlock(&atrace_tags_mutex);
-        } else {
-            // Tracing is disabled for this process, so we simply don't
-            // initialize the tags.
-            pthread_mutex_lock(&atrace_tags_mutex);
-            atrace_enabled_tags = ATRACE_TAG_NOT_READY;
-            pthread_mutex_unlock(&atrace_tags_mutex);
-        }
+    if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
+        tags = atrace_get_property();
+        pthread_mutex_lock(&atrace_tags_mutex);
+        atrace_enabled_tags = tags;
+        pthread_mutex_unlock(&atrace_tags_mutex);
+    } else {
+        // Tracing is disabled for this process, so we simply don't
+        // initialize the tags.
+        pthread_mutex_lock(&atrace_tags_mutex);
+        atrace_enabled_tags = ATRACE_TAG_NOT_READY;
+        pthread_mutex_unlock(&atrace_tags_mutex);
     }
 }
 

libcutils/trace-host.cpp

@@ -30,10 +30,8 @@ void atrace_async_begin_body(const char* /*name*/, int32_t /*cookie*/) {}
 void atrace_async_end_body(const char* /*name*/, int32_t /*cookie*/) {}
 void atrace_int_body(const char* /*name*/, int32_t /*value*/) {}
 void atrace_int64_body(const char* /*name*/, int64_t /*value*/) {}
-#if ATRACE_SHMEM
 void atrace_init() {}
 uint64_t atrace_get_enabled_tags()
 {
     return ATRACE_TAG_NOT_READY;
 }
-#endif