VM: Fix deadlock in time line recording.

runtime/vm/os_thread.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/os_thread.h"
 
 #include "vm/atomic.h"
 #include "vm/lockers.h"
 #include "vm/log.h"
 #include "vm/thread_interrupter.h"
 
 namespace dart {
 
 // The single thread local key which stores all the thread local data
 // for a thread.
 ThreadLocalKey OSThread::thread_key_ = kUnsetThreadLocalKey;
 OSThread* OSThread::thread_list_head_ = NULL;
 Mutex* OSThread::thread_list_lock_ = NULL;
 
 
 OSThread::OSThread() :
     BaseThread(true),
     id_(OSThread::GetCurrentThreadId()),
     join_id_(OSThread::GetCurrentThreadJoinId()),
     trace_id_(OSThread::GetCurrentThreadTraceId()),
     name_(NULL),
-    timeline_block_lock_(new Mutex()),
+    timeline_block_lock_(new Mutex(/* recursive = */ true)),
     timeline_block_(NULL),
     thread_list_next_(NULL),
     thread_interrupt_disabled_(1),  // Thread interrupts disabled by default.
     log_(new class Log()),
     stack_base_(0),
     thread_(NULL) {
   AddThreadToList(this);
 }
 
 
@@ skipping 194 matching lines @@
 
 OSThread* OSThreadIterator::Next() {
   ASSERT(OSThread::thread_list_lock_ != NULL);
   ASSERT(OSThread::thread_list_lock_->IsOwnedByCurrentThread());
   OSThread* current = next_;
   next_ = next_->thread_list_next_;
   return current;
 }
 
 }  // namespace dart