In Debug, SkMutex(pthread) crashes on re-entrant aquire from same thread.

src/ports/SkMutex_pthread.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkMutex_pthread_DEFINED
 #define SkMutex_pthread_DEFINED
 
 /** Posix pthread_mutex based mutex. */
 
 #include <errno.h>
 #include <pthread.h>
 
 // A SkBaseMutex is a POD structure that can be directly initialized
 // at declaration time with SK_DECLARE_STATIC/GLOBAL_MUTEX. This avoids the
 // generation of a static initializer in the final machine code (and
 // a corresponding static finalizer).
 struct SkBaseMutex {
     void acquire() {
+        SkASSERT(fOwner != pthread_self());  // SkMutex is not re-entrant

[mtklein, 2014/06/20 15:34:31]

Run this through the TSAN bot before submitting?  It may complain that this
isn't thread safe.  If so, wrap fOwner is SK_ANNOTATE_UNPROTECTED_READ.

         pthread_mutex_lock(&fMutex);
         SkDEBUGCODE(fOwner = pthread_self();)
     }
     void release() {
         this->assertHeld();
         SkDEBUGCODE(fOwner = 0;)
         pthread_mutex_unlock(&fMutex);
     }
     void assertHeld() {
         SkASSERT(pthread_self() == fOwner);
@@ skipping 50 matching lines @@
 
 #define SK_BASE_MUTEX_INIT { PTHREAD_MUTEX_INITIALIZER, SkDEBUGCODE(0) }
 
 // Using POD-style initialization prevents the generation of a static initializer.
 #define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = SK_BASE_MUTEX_INIT
 
 // Special case used when the static mutex must be available globally.
 #define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name = SK_BASE_MUTEX_INIT
 
 #endif