when pthread exits or is cancelled, mutexes held by thread are marked inconsistent and the highest priority thread waiting for the mutex is awakened.

sched/pthread/Make.defs

@@ -39,7 +39,7 @@ CSRCS += pthread_create.c pthread_exit.c pthread_join.c pthread_detach.c
 CSRCS += pthread_yield.c pthread_getschedparam.c pthread_setschedparam.c
 CSRCS += pthread_mutexinit.c pthread_mutexdestroy.c pthread_mutex.c
 CSRCS += pthread_mutexlock.c pthread_mutextrylock.c pthread_mutexunlock.c
-CSRCS += pthread_mutexconsistent.c
+CSRCS += pthread_mutexconsistent.c pthread_mutexinconsistent.c
 CSRCS += pthread_condinit.c pthread_conddestroy.c
 CSRCS += pthread_condwait.c pthread_condsignal.c pthread_condbroadcast.c
 CSRCS += pthread_barrierinit.c pthread_barrierdestroy.c pthread_barrierwait.c

sched/pthread/pthread.h

@@ -111,6 +111,7 @@ int pthread_takesemaphore(sem_t *sem, bool intr);
 int pthread_givesemaphore(sem_t *sem);
 int pthread_takemutex(FAR struct pthread_mutex_s *mutex, bool intr);
 int pthread_givemutex(FAR struct pthread_mutex_s *mutex);
+void pthread_mutex_inconsistent(FAR struct pthread_tcb_s *tcb);
 
 #ifdef CONFIG_MUTEX_TYPES
 int pthread_mutexattr_verifytype(int type);

sched/pthread/pthread_cancel.c

@@ -162,6 +162,10 @@ int pthread_cancel(pthread_t thread)
 
   (void)pthread_completejoin((pid_t)thread, PTHREAD_CANCELED);
 
+  /* Recover any mutexes still held by the canceled thread */
+
+  pthread_mutex_inconsistent(tcb);
+
   /* Then let task_terminate do the real work */
 
   return task_terminate((pid_t)thread, false);

sched/pthread/pthread_exit.c

@@ -123,6 +123,10 @@ void pthread_exit(FAR void *exit_value)
       exit(EXIT_FAILURE);
     }
 
+  /* Recover any mutexes still held by the canceled thread */
+
+  pthread_mutex_inconsistent(tcb);
+
   /* Perform common task termination logic.  This will get called again later
    * through logic kicked off by _exit().  However, we need to call it before
    * calling _exit() in order certain operations if this is the last thread

sched/pthread/pthread_mutexinit.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * sched/pthread/pthread_mutexinit.c
  *
- *   Copyright (C) 2007-2009, 2011, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -123,6 +123,10 @@ int pthread_mutex_init(FAR pthread_mutex_t *mutex,
           ret = get_errno();
         }
 #endif
+      /* Initial internal fields of the mutex */
+
+      mutex->flink  = NULL;
+      mutex->flags  = 0;
 
       /* Set up attributes unique to the mutex type */