Annotate ThreadData::PushToHeadOfList for MemorySanitizer.

base/tracked_objects.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/tracked_objects.h"
 
 #include <math.h>
 #include <stdlib.h>
 
+#include "base/compiler_specific.h"
 #include "base/format_macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/process_util.h"
 #include "base/profiler/alternate_timer.h"
 #include "base/stringprintf.h"
 #include "base/third_party/valgrind/memcheck.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/port.h"
 
 using base::TimeDelta;
@@ skipping 231 matching lines @@
   base::StringAppendF(&thread_name_, "WorkerThread-%d", thread_number);
   PushToHeadOfList();  // Which sets real incarnation_count_for_pool_.
 }
 
 ThreadData::~ThreadData() {}
 
 void ThreadData::PushToHeadOfList() {
   // Toss in a hint of randomness (atop the uniniitalized value).
   (void)VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE(&random_number_,
                                                  sizeof(random_number_));
+  __msan_unpoison(&random_number_, sizeof(random_number_));

[Alexander Potapenko, 2013/03/20 11:19:43]

As I've said before, it isn't obvious that __msan_unpoison() is a no-op if
MEMORY_SANITIZER is not defined.

I suggest to:
 - remove the leading underscores, since they denote that the identifier is
reserved by the compiler (this is ok under '#ifdef MEMORY_SANITIZER', but not in
the regular mode)
 - use uppercase only (to show this is a macro, not a function call)

   random_number_ += static_cast<int32>(this - static_cast<ThreadData*>(0));
   random_number_ ^= (Now() - TrackedTime()).InMilliseconds();
 
   DCHECK(!next_);
   base::AutoLock lock(*list_lock_.Pointer());
   incarnation_count_for_pool_ = incarnation_counter_;
   next_ = all_thread_data_list_head_;
   all_thread_data_list_head_ = this;
 }
 
@@ skipping 590 matching lines @@
     : process_id(base::GetCurrentProcId()) {
 #else
     : process_id(0) {
 #endif
 }
 
 ProcessDataSnapshot::~ProcessDataSnapshot() {
 }
 
 }  // namespace tracked_objects