Revert "Adding system property tracing"

Revert submission 1403568-sysprop_trace

Reason for revert: makes property get/set non-reentrant
Reverted Changes:
I6f85f3f52:Add systrace tag for system property
Id2b93acb2:Adding system property tracing
Id78992d23:Add systrace tag for system property
I1ba9fc7bd:Add systrace tag for system property

Bug: 193050299
Test: build and boot a device
Change-Id: Ic7a83fb01a39113d408ed0c95d27f694d5a2649c
Merged-In: Ic7a83fb01a39113d408ed0c95d27f694d5a2649c
(cherry picked from commit 61a5a8380d)

libc/Android.bp

@@ -1202,6 +1202,7 @@ cc_library_static {
         },
     },
     whole_static_libs: [
+        "libc_bionic_systrace",
         "libsystemproperties",
     ],
     cppflags: ["-Wold-style-cast"],

libc/bionic/bionic_systrace.cpp

@@ -14,41 +14,36 @@
  * 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;
 
-static CachedProperty& GetTagsProp() {
+static bool should_trace() {
-  static CachedProperty cached_property(kTraceTagsProp);
-  return cached_property;
-}
-
-bool should_trace(const uint64_t enable_tags) {
   g_lock.lock();
-  if (GetTagsProp().DidChange()) {
+  if (g_debug_atrace_tags_enableflags.DidChange()) {
-    g_tags = strtoull(GetTagsProp().Get(), nullptr, 0);
+    g_tags = strtoull(g_debug_atrace_tags_enableflags.Get(), nullptr, 0);
   }
   g_lock.unlock();
-  return g_tags & enable_tags;
+  return ((g_tags & ATRACE_TAG_BIONIC) != 0);
 }
 
-int get_trace_marker_fd() {
+static int get_trace_marker_fd() {
   g_lock.lock();
   if (g_trace_marker_fd == -1) {
     g_trace_marker_fd = open("/sys/kernel/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
@@ -60,8 +55,11 @@ int get_trace_marker_fd() {
   return g_trace_marker_fd;
 }
 
-// event could be 'B' for begin or 'E' for end.
+void bionic_trace_begin(const char* message) {
-void output_trace(const char* message, const char event) {
+  if (!should_trace()) {
+    return;
+  }
+
   int trace_marker_fd = get_trace_marker_fd();
   if (trace_marker_fd == -1) {
     return;
@@ -71,22 +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 =
+  size_t len = async_safe_format_buffer(buf, length + WRITE_OFFSET, "B|%d|%s", getpid(), message);
-      async_safe_format_buffer(buf, length + WRITE_OFFSET, "%c|%d|%s", event, 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;

libc/bionic/system_property_set.cpp

@@ -41,13 +41,12 @@
 #include <sys/_system_properties.h>
 #include <unistd.h>
 
-#include <async_safe/CHECK.h>
 #include <async_safe/log.h>
-#include <system_properties/prop_trace.h>
+#include <async_safe/CHECK.h>
 
+#include "private/bionic_defs.h"
 #include "platform/bionic/macros.h"
 #include "private/ScopedFd.h"
-#include "private/bionic_defs.h"
 
 static const char property_service_socket[] = "/dev/socket/" PROP_SERVICE_NAME;
 static const char* kServiceVersionPropertyName = "ro.property_service.version";
@@ -250,8 +249,6 @@ int __system_property_set(const char* key, const char* value) {
   if (key == nullptr) return -1;
   if (value == nullptr) value = "";
 
-  SyspropTrace trace(key, value, nullptr /* prop_info */, PropertyAction::kPropertySet);
-
   if (g_propservice_protocol_version == 0) {
     detect_protocol_version();
   }

libc/private/bionic_systrace.h

@@ -16,12 +16,8 @@
 
 #pragma once
 
-#include <cutils/trace.h>  // For ATRACE_TAG_BIONIC.
-
 #include "platform/bionic/macros.h"
 
-static constexpr char kTraceTagsProp[] = "debug.atrace.tags.enableflags";
-
 // Tracing class for bionic. To begin a trace at a specified point:
 //   ScopedTrace("Trace message");
 // The trace will end when the contructor goes out of scope.
@@ -37,9 +33,5 @@ class __LIBC_HIDDEN__ ScopedTrace {
   BIONIC_DISALLOW_COPY_AND_ASSIGN(ScopedTrace);
 };
 
-int get_trace_marker_fd();
-bool should_trace(const uint64_t enable_tags = ATRACE_TAG_BIONIC);
-void output_trace(const char* message, const char event = 'B');
-
 void bionic_trace_begin(const char* message);
 void bionic_trace_end();

libc/system_properties/Android.bp

@@ -18,11 +18,9 @@ cc_library_static {
         "contexts_serialized.cpp",
         "prop_area.cpp",
         "prop_info.cpp",
-        "prop_trace.cpp",
         "system_properties.cpp",
     ],
     whole_static_libs: [
-        "libc_bionic_systrace",
         "libpropertyinfoparser",
     ],
     header_libs: [

libc/system_properties/include/system_properties/prop_trace.h

@@ -1,49 +0,0 @@
-/*
- * Copyright (C) 2020 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include "platform/bionic/macros.h"
-
-#include "prop_info.h"
-
-// Tracing class for sysprop. To begin a trace at a specified point:
-//   SyspropTrace trace ("prop_name", "prop_value");
-// The trace will end when the constructor goes out of scope.
-// For read-only properties (ro.*), also need to pass prop_info struct.
-
-enum class PropertyAction {
-  kPropertyFind = 0,
-  kPropertySet,
-  kPropertyGetReadOnly,
-  kPropertyGetReadWrite,
-};
-
-class __LIBC_HIDDEN__ SyspropTrace {
- public:
-  explicit SyspropTrace(const char* prop_name, const char* prop_value, const prop_info* pi,
-                        PropertyAction action);
-  ~SyspropTrace();
-
- private:
-  const char* prop_name_;
-  const char* prop_value_;
-  const prop_info* prop_info_;
-  PropertyAction prop_action_;
-  bool output_trace_;
-
-  BIONIC_DISALLOW_COPY_AND_ASSIGN(SyspropTrace);
-};

libc/system_properties/prop_trace.cpp

@@ -1,113 +0,0 @@
-/*
- * Copyright (C) 2020 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "system_properties/prop_trace.h"
-
-#include <errno.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "private/CachedProperty.h"
-#include "private/bionic_lock.h"
-#include "private/bionic_systrace.h"
-
-#include <async_safe/log.h>
-#include <cutils/trace.h>  // For ATRACE_TAG_SYSPROP.
-
-#define PROP_TRACE_MSG_LENGTH 1024
-
-static bool should_trace_prop(const char* prop_name) {
-  // Should not trace kTraceTagsProp to avoid infinite recursion.
-  // Because the following g_trace_enable_flags.Get() will get the property value
-  // of kTraceTagsProp again, which in turn invokes should_trace_prop() here.
-  if (prop_name == nullptr || !strcmp(prop_name, kTraceTagsProp)) {
-    return false;
-  }
-
-  return should_trace(ATRACE_TAG_SYSPROP);
-}
-
-static void sysprop_trace_end() {
-  int trace_marker_fd = get_trace_marker_fd();
-  if (trace_marker_fd == -1) {
-    return;
-  }
-
-  TEMP_FAILURE_RETRY(write(trace_marker_fd, "E|", 2));
-}
-
-static void get_sysprop_trace_end(const prop_info* pi, const char* prop_value,
-                                  bool read_only = false) {
-  const char* output_value;
-  char message[PROP_TRACE_MSG_LENGTH];
-
-  if (read_only) {
-    if (pi->is_long()) {
-      output_value = pi->long_value();
-    } else {
-      output_value = pi->value;
-    }
-  } else {
-    output_value = prop_value;
-  }
-
-  snprintf(message, sizeof(message), "prop_get: %s, value: %s", pi->name,
-           output_value ? output_value : "null_value");
-  output_trace(message, 'E');  // 'E' for end.
-}
-
-SyspropTrace::SyspropTrace(const char* prop_name, const char* prop_value, const prop_info* pi,
-                           PropertyAction action)
-    : prop_name_(prop_name),
-      prop_value_(prop_value),
-      prop_info_(pi),
-      prop_action_(action),
-      output_trace_(false) {
-  if (!should_trace_prop(prop_name)) {
-    return;
-  }
-
-  char message[PROP_TRACE_MSG_LENGTH];
-  if (prop_action_ == PropertyAction::kPropertyFind) {
-    snprintf(message, sizeof(message), "prop_find: %s", prop_name_);
-  } else if (prop_action_ == PropertyAction::kPropertySet) {
-    snprintf(message, sizeof(message), "prop_set: %s, value: %s", prop_name_,
-             prop_value_ ? prop_value_ : "null_value");
-  } else {
-    // For property get, the prop_value_ will be resolved then printed in the destructor.
-    snprintf(message, sizeof(message), "prop_get: %s", prop_name_);
-  }
-
-  output_trace(message, 'B');  // 'B' for begin.
-  output_trace_ = true;
-}
-
-SyspropTrace::~SyspropTrace() {
-  if (!output_trace_) {
-    return;
-  }
-  if (prop_action_ == PropertyAction::kPropertyFind ||
-      prop_action_ == PropertyAction::kPropertySet) {
-    sysprop_trace_end();
-  } else if (prop_action_ == PropertyAction::kPropertyGetReadOnly) {
-    get_sysprop_trace_end(prop_info_, prop_value_, true /* read_only */);
-  } else if (prop_action_ == PropertyAction::kPropertyGetReadWrite) {
-    get_sysprop_trace_end(prop_info_, prop_value_, false /* read_only */);
-  }
-  output_trace_ = false;
-}

libc/system_properties/system_properties.cpp

@@ -46,7 +46,6 @@
 #include "system_properties/context_node.h"
 #include "system_properties/prop_area.h"
 #include "system_properties/prop_info.h"
-#include "system_properties/prop_trace.h"
 
 #define SERIAL_DIRTY(serial) ((serial)&1)
 #define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
@@ -128,9 +127,6 @@ const prop_info* SystemProperties::Find(const char* name) {
     return nullptr;
   }
 
-  SyspropTrace trace(name, nullptr /* prop_value */, nullptr /* prop_info */,
-                     PropertyAction::kPropertyFind);
-
   prop_area* pa = contexts_->GetPropAreaForName(name);
   if (!pa) {
     async_safe_format_log(ANDROID_LOG_WARN, "libc", "Access denied finding property \"%s\"", name);
@@ -205,10 +201,6 @@ void SystemProperties::ReadCallback(const prop_info* pi,
   // Read only properties don't need to copy the value to a temporary buffer, since it can never
   // change.  We use relaxed memory order on the serial load for the same reason.
   if (is_read_only(pi->name)) {
-    // The 2nd argument is not required for read-only property tracing, as the
-    // value can be obtained via pi->value or pi->long_value().
-    SyspropTrace trace(pi->name, nullptr /* prop_value */, pi /* prop_info */,
-                       PropertyAction::kPropertyGetReadOnly);
     uint32_t serial = load_const_atomic(&pi->serial, memory_order_relaxed);
     if (pi->is_long()) {
       callback(cookie, pi->name, pi->long_value(), serial);
@@ -219,8 +211,6 @@ void SystemProperties::ReadCallback(const prop_info* pi,
   }
 
   char value_buf[PROP_VALUE_MAX];
-  SyspropTrace trace(pi->name, value_buf, pi /* prop_info */,
-                     PropertyAction::kPropertyGetReadWrite);
   uint32_t serial = ReadMutablePropertyValue(pi, value_buf);
   callback(cookie, pi->name, value_buf, serial);
 }