Add implementation of robust mutexes, hopefully close enough to the

intention of the POSIX IEEE Std 1003.1TM-2008/Cor 1-2013.

A robust mutex is guaranteed to be cleared by the system upon either
thread or process owner termination while the mutex is held.  The next
mutex locker is then notified about inconsistent mutex state and can
execute (or abandon) corrective actions.

The patch mostly consists of small changes here and there, adding
neccessary checks for the inconsistent and abandoned conditions into
existing paths.  Additionally, the thread exit handler was extended to
iterate over the userspace-maintained list of owned robust mutexes,
unlocking and marking as terminated each of them.

The list of owned robust mutexes cannot be maintained atomically
synchronous with the mutex lock state (it is possible in kernel, but
is too expensive).  Instead, for the duration of lock or unlock
operation, the current mutex is remembered in a special slot that is
also checked by the kernel at thread termination.

Kernel must be aware about the per-thread location of the heads of
robust mutex lists and the current active mutex slot.  When a thread
touches a robust mutex for the first time, a new umtx op syscall is
issued which informs about location of lists heads.

The umtx sleep queues for PP and PI mutexes are split between
non-robust and robust.

Somewhat unrelated changes in the patch:
1. Style.
2. The fix for proper tdfind() call use in umtxq_sleep_pi() for shared
   pi mutexes.
3. Removal of the userspace struct pthread_mutex m_owner field.
4. The sysctl kern.ipc.umtx_vnode_persistent is added, which controls
   the lifetime of the shared mutex associated with a vnode' page.

Reviewed by:	jilles (previous version, supposedly the objection was fixed)
Discussed with:	brooks, Martin Simmons <martin@lispworks.com> (some aspects)
Tested by:	pho
Sponsored by:	The FreeBSD Foundation

1 files changed, 277 insertions, 103 deletions

diff --git a/lib/libthr/thread/thr_mutex.c b/lib/libthr/thread/thr_mutex.c
index f75ea6f..2d507e7 100644
--- a/lib/libthr/thread/thr_mutex.c
+++ b/lib/libthr/thread/thr_mutex.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
  * Copyright (c) 2006 David Xu <davidxu@freebsd.org>.
- * Copyright (c) 2015 The FreeBSD Foundation
+ * Copyright (c) 2015, 2016 The FreeBSD Foundation
  *
  * All rights reserved.
  *
@@ -39,7 +39,6 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
-#include <stdbool.h>
 #include "namespace.h"
 #include <stdlib.h>
 #include <errno.h>
@@ -64,6 +63,7 @@ _Static_assert(sizeof(struct pthread_mutex) <= PAGE_SIZE,
 /*
  * Prototypes
  */
+int	__pthread_mutex_consistent(pthread_mutex_t *mutex);
 int	__pthread_mutex_init(pthread_mutex_t *mutex,
 		const pthread_mutexattr_t *mutex_attr);
 int	__pthread_mutex_trylock(pthread_mutex_t *mutex);
@@ -82,9 +82,13 @@ int	__pthread_mutex_setyieldloops_np(pthread_mutex_t *mutex, int count);
 static int	mutex_self_trylock(pthread_mutex_t);
 static int	mutex_self_lock(pthread_mutex_t,
 				const struct timespec *abstime);
-static int	mutex_unlock_common(struct pthread_mutex *, int, int *);
+static int	mutex_unlock_common(struct pthread_mutex *, bool, int *);
 static int	mutex_lock_sleep(struct pthread *, pthread_mutex_t,
 				const struct timespec *);
+static void	mutex_init_robust(struct pthread *curthread);
+static int	mutex_qidx(struct pthread_mutex *m);
+static bool	is_robust_mutex(struct pthread_mutex *m);
+static bool	is_pshared_mutex(struct pthread_mutex *m);
 
 __weak_reference(__pthread_mutex_init, pthread_mutex_init);
 __strong_reference(__pthread_mutex_init, _pthread_mutex_init);
@@ -94,6 +98,8 @@ __weak_reference(__pthread_mutex_timedlock, pthread_mutex_timedlock);
 __strong_reference(__pthread_mutex_timedlock, _pthread_mutex_timedlock);
 __weak_reference(__pthread_mutex_trylock, pthread_mutex_trylock);
 __strong_reference(__pthread_mutex_trylock, _pthread_mutex_trylock);
+__weak_reference(_pthread_mutex_consistent, pthread_mutex_consistent);
+__strong_reference(_pthread_mutex_consistent, __pthread_mutex_consistent);
 
 /* Single underscore versions provided for libc internal usage: */
 /* No difference between libc and application usage of these: */
@@ -125,23 +131,23 @@ mutex_init_link(struct pthread_mutex *m)
 }
 
 static void
-mutex_assert_is_owned(struct pthread_mutex *m)
+mutex_assert_is_owned(struct pthread_mutex *m __unused)
 {
 
 #if defined(_PTHREADS_INVARIANTS)
 	if (__predict_false(m->m_qe.tqe_prev == NULL)) {
 		char msg[128];
 		snprintf(msg, sizeof(msg),
-		    "mutex %p own %#x %#x is not on list %p %p",
-		    m, m->m_lock.m_owner, m->m_owner, m->m_qe.tqe_prev,
-		    m->m_qe.tqe_next);
+		    "mutex %p own %#x is not on list %p %p",
+		    m, m->m_lock.m_owner, m->m_qe.tqe_prev, m->m_qe.tqe_next);
 		PANIC(msg);
 	}
 #endif
 }
 
 static void
-mutex_assert_not_owned(struct pthread_mutex *m)
+mutex_assert_not_owned(struct pthread *curthread __unused,
+    struct pthread_mutex *m __unused)
 {
 
 #if defined(_PTHREADS_INVARIANTS)
@@ -149,21 +155,68 @@ mutex_assert_not_owned(struct pthread_mutex *m)
 	    m->m_qe.tqe_next != NULL)) {
 		char msg[128];
 		snprintf(msg, sizeof(msg),
-		    "mutex %p own %#x %#x is on list %p %p",
-		    m, m->m_lock.m_owner, m->m_owner, m->m_qe.tqe_prev,
-		    m->m_qe.tqe_next);
+		    "mutex %p own %#x is on list %p %p",
+		    m, m->m_lock.m_owner, m->m_qe.tqe_prev, m->m_qe.tqe_next);
+		PANIC(msg);
+	}
+	if (__predict_false(is_robust_mutex(m) &&
+	    (m->m_lock.m_rb_lnk != 0 || m->m_rb_prev != NULL ||
+	    (is_pshared_mutex(m) && curthread->robust_list ==
+	    (uintptr_t)&m->m_lock) ||
+	    (!is_pshared_mutex(m) && curthread->priv_robust_list ==
+	    (uintptr_t)&m->m_lock)))) {
+		char msg[128];
+		snprintf(msg, sizeof(msg),
+    "mutex %p own %#x is on robust linkage %p %p head %p phead %p",
+		    m, m->m_lock.m_owner, (void *)m->m_lock.m_rb_lnk,
+		    m->m_rb_prev, (void *)curthread->robust_list,
+		    (void *)curthread->priv_robust_list);
 		PANIC(msg);
 	}
 #endif
 }
 
-static int
+static bool
 is_pshared_mutex(struct pthread_mutex *m)
 {
 
 	return ((m->m_lock.m_flags & USYNC_PROCESS_SHARED) != 0);
 }
 
+static bool
+is_robust_mutex(struct pthread_mutex *m)
+{
+
+	return ((m->m_lock.m_flags & UMUTEX_ROBUST) != 0);
+}
+
+int
+_mutex_enter_robust(struct pthread *curthread, struct pthread_mutex *m)
+{
+
+#if defined(_PTHREADS_INVARIANTS)
+	if (__predict_false(curthread->inact_mtx != 0))
+		PANIC("inact_mtx enter");
+#endif
+	if (!is_robust_mutex(m))
+		return (0);
+
+	mutex_init_robust(curthread);
+	curthread->inact_mtx = (uintptr_t)&m->m_lock;
+	return (1);
+}
+
+void
+_mutex_leave_robust(struct pthread *curthread, struct pthread_mutex *m __unused)
+{
+
+#if defined(_PTHREADS_INVARIANTS)
+	if (__predict_false(curthread->inact_mtx != (uintptr_t)&m->m_lock))
+		PANIC("inact_mtx leave");
+#endif
+	curthread->inact_mtx = 0;
+}
+
 static int
 mutex_check_attr(const struct pthread_mutex_attr *attr)
 {
@@ -178,12 +231,27 @@ mutex_check_attr(const struct pthread_mutex_attr *attr)
 }
 
 static void
+mutex_init_robust(struct pthread *curthread)
+{
+	struct umtx_robust_lists_params rb;
+
+	if (curthread == NULL)
+		curthread = _get_curthread();
+	if (curthread->robust_inited)
+		return;
+	rb.robust_list_offset = (uintptr_t)&curthread->robust_list;
+	rb.robust_priv_list_offset = (uintptr_t)&curthread->priv_robust_list;
+	rb.robust_inact_offset = (uintptr_t)&curthread->inact_mtx;
+	_umtx_op(NULL, UMTX_OP_ROBUST_LISTS, sizeof(rb), &rb, NULL);
+	curthread->robust_inited = 1;
+}
+
+static void
 mutex_init_body(struct pthread_mutex *pmutex,
     const struct pthread_mutex_attr *attr)
 {
 
 	pmutex->m_flags = attr->m_type;
-	pmutex->m_owner = 0;
 	pmutex->m_count = 0;
 	pmutex->m_spinloops = 0;
 	pmutex->m_yieldloops = 0;
@@ -205,7 +273,10 @@ mutex_init_body(struct pthread_mutex *pmutex,
 	}
 	if (attr->m_pshared == PTHREAD_PROCESS_SHARED)
 		pmutex->m_lock.m_flags |= USYNC_PROCESS_SHARED;
-
+	if (attr->m_robust == PTHREAD_MUTEX_ROBUST) {
+		mutex_init_robust(NULL);
+		pmutex->m_lock.m_flags |= UMUTEX_ROBUST;
+	}
 	if (PMUTEX_TYPE(pmutex->m_flags) == PTHREAD_MUTEX_ADAPTIVE_NP) {
 		pmutex->m_spinloops =
 		    _thr_spinloops ? _thr_spinloops: MUTEX_ADAPTIVE_SPINS;
@@ -262,7 +333,7 @@ set_inherited_priority(struct pthread *curthread, struct pthread_mutex *m)
 {
 	struct pthread_mutex *m2;
 
-	m2 = TAILQ_LAST(&curthread->mq[TMQ_NORM_PP], mutex_queue);
+	m2 = TAILQ_LAST(&curthread->mq[mutex_qidx(m)], mutex_queue);
 	if (m2 != NULL)
 		m->m_lock.m_ceilings[1] = m2->m_lock.m_ceilings[0];
 	else
@@ -277,7 +348,8 @@ shared_mutex_init(struct pthread_mutex *pmtx, const struct
 		.m_type = PTHREAD_MUTEX_DEFAULT,
 		.m_protocol = PTHREAD_PRIO_NONE,
 		.m_ceiling = 0,
-		.m_pshared = PTHREAD_PROCESS_SHARED
+		.m_pshared = PTHREAD_PROCESS_SHARED,
+		.m_robust = PTHREAD_MUTEX_STALLED,
 	};
 	bool done;
 
@@ -329,7 +401,7 @@ __pthread_mutex_init(pthread_mutex_t *mutex,
 	if (mutex_attr == NULL ||
 	    (*mutex_attr)->m_pshared == PTHREAD_PROCESS_PRIVATE) {
 		return (mutex_init(mutex, mutex_attr ? *mutex_attr : NULL,
-		   calloc));
+		    calloc));
 	}
 	pmtx = __thr_pshared_offpage(mutex, 1);
 	if (pmtx == NULL)
@@ -349,6 +421,7 @@ _pthread_mutex_init_calloc_cb(pthread_mutex_t *mutex,
 		.m_protocol = PTHREAD_PRIO_NONE,
 		.m_ceiling = 0,
 		.m_pshared = PTHREAD_PROCESS_PRIVATE,
+		.m_robust = PTHREAD_MUTEX_STALLED,
 	};
 	int ret;
 
@@ -378,7 +451,6 @@ queue_fork(struct pthread *curthread, struct mutex_queue *q,
 	TAILQ_FOREACH(m, qp, m_pqe) {
 		TAILQ_INSERT_TAIL(q, m, m_qe);
 		m->m_lock.m_owner = TID(curthread) | bit;
-		m->m_owner = TID(curthread);
 	}
 }
 
@@ -390,6 +462,9 @@ _mutex_fork(struct pthread *curthread)
 	    &curthread->mq[TMQ_NORM_PRIV], 0);
 	queue_fork(curthread, &curthread->mq[TMQ_NORM_PP],
 	    &curthread->mq[TMQ_NORM_PP_PRIV], UMUTEX_CONTESTED);
+	queue_fork(curthread, &curthread->mq[TMQ_ROBUST_PP],
+	    &curthread->mq[TMQ_ROBUST_PP_PRIV], UMUTEX_CONTESTED);
+	curthread->robust_list = 0;
 }
 
 int
@@ -407,17 +482,18 @@ _pthread_mutex_destroy(pthread_mutex_t *mutex)
 		if (m == THR_PSHARED_PTR) {
 			m1 = __thr_pshared_offpage(mutex, 0);
 			if (m1 != NULL) {
-				mutex_assert_not_owned(m1);
+				mutex_assert_not_owned(_get_curthread(), m1);
 				__thr_pshared_destroy(mutex);
 			}
 			*mutex = THR_MUTEX_DESTROYED;
 			return (0);
 		}
-		if (m->m_owner != 0) {
+		if (PMUTEX_OWNER_ID(m) != 0 &&
+		    (uint32_t)m->m_lock.m_owner != UMUTEX_RB_NOTRECOV) {
 			ret = EBUSY;
 		} else {
 			*mutex = THR_MUTEX_DESTROYED;
-			mutex_assert_not_owned(m);
+			mutex_assert_not_owned(_get_curthread(), m);
 			free(m);
 			ret = 0;
 		}
@@ -432,31 +508,81 @@ mutex_qidx(struct pthread_mutex *m)
 
 	if ((m->m_lock.m_flags & UMUTEX_PRIO_PROTECT) == 0)
 		return (TMQ_NORM);
-	return (TMQ_NORM_PP);
+	return (is_robust_mutex(m) ? TMQ_ROBUST_PP : TMQ_NORM_PP);
 }
 
+/*
+ * Both enqueue_mutex() and dequeue_mutex() operate on the
+ * thread-private linkage of the locked mutexes and on the robust
+ * linkage.
+ *
+ * Robust list, as seen by kernel, must be consistent even in the case
+ * of thread termination at arbitrary moment.  Since either enqueue or
+ * dequeue for list walked by kernel consists of rewriting a single
+ * forward pointer, it is safe.  On the other hand, rewrite of the
+ * back pointer is not atomic WRT the forward one, but kernel does not
+ * care.
+ */
 static void
-enqueue_mutex(struct pthread *curthread, struct pthread_mutex *m)
+enqueue_mutex(struct pthread *curthread, struct pthread_mutex *m,
+    int error)
 {
+	struct pthread_mutex *m1;
+	uintptr_t *rl;
 	int qidx;
 
-	m->m_owner = TID(curthread);
 	/* Add to the list of owned mutexes: */
-	mutex_assert_not_owned(m);
+	if (error != EOWNERDEAD)
+		mutex_assert_not_owned(curthread, m);
 	qidx = mutex_qidx(m);
 	TAILQ_INSERT_TAIL(&curthread->mq[qidx], m, m_qe);
 	if (!is_pshared_mutex(m))
 		TAILQ_INSERT_TAIL(&curthread->mq[qidx + 1], m, m_pqe);
+	if (is_robust_mutex(m)) {
+		rl = is_pshared_mutex(m) ? &curthread->robust_list :
+		    &curthread->priv_robust_list;
+		m->m_rb_prev = NULL;
+		if (*rl != 0) {
+			m1 = __containerof((void *)*rl,
+			    struct pthread_mutex, m_lock);
+			m->m_lock.m_rb_lnk = (uintptr_t)&m1->m_lock;
+			m1->m_rb_prev = m;
+		} else {
+			m1 = NULL;
+			m->m_lock.m_rb_lnk = 0;
+		}
+		*rl = (uintptr_t)&m->m_lock;
+	}
 }
 
 static void
 dequeue_mutex(struct pthread *curthread, struct pthread_mutex *m)
 {
+	struct pthread_mutex *mp, *mn;
 	int qidx;
 
-	m->m_owner = 0;
 	mutex_assert_is_owned(m);
 	qidx = mutex_qidx(m);
+	if (is_robust_mutex(m)) {
+		mp = m->m_rb_prev;
+		if (mp == NULL) {
+			if (is_pshared_mutex(m)) {
+				curthread->robust_list = m->m_lock.m_rb_lnk;
+			} else {
+				curthread->priv_robust_list =
+				    m->m_lock.m_rb_lnk;
+			}
+		} else {
+			mp->m_lock.m_rb_lnk = m->m_lock.m_rb_lnk;
+		}
+		if (m->m_lock.m_rb_lnk != 0) {
+			mn = __containerof((void *)m->m_lock.m_rb_lnk,
+			    struct pthread_mutex, m_lock);
+			mn->m_rb_prev = m->m_rb_prev;
+		}
+		m->m_lock.m_rb_lnk = 0;
+		m->m_rb_prev = NULL;
+	}
 	TAILQ_REMOVE(&curthread->mq[qidx], m, m_qe);
 	if (!is_pshared_mutex(m))
 		TAILQ_REMOVE(&curthread->mq[qidx + 1], m, m_pqe);
@@ -496,7 +622,7 @@ __pthread_mutex_trylock(pthread_mutex_t *mutex)
 	struct pthread *curthread;
 	struct pthread_mutex *m;
 	uint32_t id;
-	int ret;
+	int ret, robust;
 
 	ret = check_and_init_mutex(mutex, &m);
 	if (ret != 0)
@@ -505,27 +631,32 @@ __pthread_mutex_trylock(pthread_mutex_t *mutex)
 	id = TID(curthread);
 	if (m->m_flags & PMUTEX_FLAG_PRIVATE)
 		THR_CRITICAL_ENTER(curthread);
+	robust = _mutex_enter_robust(curthread, m);
 	ret = _thr_umutex_trylock(&m->m_lock, id);
-	if (__predict_true(ret == 0)) {
-		enqueue_mutex(curthread, m);
-	} else if (m->m_owner == id) {
+	if (__predict_true(ret == 0) || ret == EOWNERDEAD) {
+		enqueue_mutex(curthread, m, ret);
+		if (ret == EOWNERDEAD)
+			m->m_lock.m_flags |= UMUTEX_NONCONSISTENT;
+	} else if (PMUTEX_OWNER_ID(m) == id) {
 		ret = mutex_self_trylock(m);
 	} /* else {} */
-	if (ret && (m->m_flags & PMUTEX_FLAG_PRIVATE))
+	if (robust)
+		_mutex_leave_robust(curthread, m);
+	if ((ret == 0 || ret == EOWNERDEAD) &&
+	    (m->m_flags & PMUTEX_FLAG_PRIVATE) != 0)
 		THR_CRITICAL_LEAVE(curthread);
 	return (ret);
 }
 
 static int
 mutex_lock_sleep(struct pthread *curthread, struct pthread_mutex *m,
-	const struct timespec *abstime)
+    const struct timespec *abstime)
 {
-	uint32_t	id, owner;
-	int	count;
-	int	ret;
+	uint32_t id, owner;
+	int count, ret;
 
 	id = TID(curthread);
-	if (m->m_owner == id)
+	if (PMUTEX_OWNER_ID(m) == id)
 		return (mutex_self_lock(m, abstime));
 
 	/*
@@ -534,10 +665,9 @@ mutex_lock_sleep(struct pthread *curthread, struct pthread_mutex *m,
 	 * the lock is likely to be released quickly and it is
 	 * faster than entering the kernel
 	 */
-	if (__predict_false(
-		(m->m_lock.m_flags & 
-		 (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT)) != 0))
-			goto sleep_in_kernel;
+	if (__predict_false((m->m_lock.m_flags & (UMUTEX_PRIO_PROTECT |
+	    UMUTEX_PRIO_INHERIT | UMUTEX_ROBUST | UMUTEX_NONCONSISTENT)) != 0))
+		goto sleep_in_kernel;
 
 	if (!_thr_is_smp)
 		goto yield_loop;
@@ -546,7 +676,8 @@ mutex_lock_sleep(struct pthread *curthread, struct pthread_mutex *m,
 	while (count--) {
 		owner = m->m_lock.m_owner;
 		if ((owner & ~UMUTEX_CONTESTED) == 0) {
-			if (atomic_cmpset_acq_32(&m->m_lock.m_owner, owner, id|owner)) {
+			if (atomic_cmpset_acq_32(&m->m_lock.m_owner, owner,
+			    id | owner)) {
 				ret = 0;
 				goto done;
 			}
@@ -560,7 +691,8 @@ yield_loop:
 		_sched_yield();
 		owner = m->m_lock.m_owner;
 		if ((owner & ~UMUTEX_CONTESTED) == 0) {
-			if (atomic_cmpset_acq_32(&m->m_lock.m_owner, owner, id|owner)) {
+			if (atomic_cmpset_acq_32(&m->m_lock.m_owner, owner,
+			    id | owner)) {
 				ret = 0;
 				goto done;
 			}
@@ -568,38 +700,46 @@ yield_loop:
 	}
 
 sleep_in_kernel:
-	if (abstime == NULL) {
+	if (abstime == NULL)
 		ret = __thr_umutex_lock(&m->m_lock, id);
-	} else if (__predict_false(
-		   abstime->tv_nsec < 0 ||
-		   abstime->tv_nsec >= 1000000000)) {
+	else if (__predict_false(abstime->tv_nsec < 0 ||
+	    abstime->tv_nsec >= 1000000000))
 		ret = EINVAL;
-	} else {
+	else
 		ret = __thr_umutex_timedlock(&m->m_lock, id, abstime);
-	}
 done:
-	if (ret == 0)
-		enqueue_mutex(curthread, m);
-
+	if (ret == 0 || ret == EOWNERDEAD) {
+		enqueue_mutex(curthread, m, ret);
+		if (ret == EOWNERDEAD)
+			m->m_lock.m_flags |= UMUTEX_NONCONSISTENT;
+	}
 	return (ret);
 }
 
 static inline int
-mutex_lock_common(struct pthread_mutex *m,
-	const struct timespec *abstime, int cvattach)
+mutex_lock_common(struct pthread_mutex *m, const struct timespec *abstime,
+    bool cvattach, bool rb_onlist)
 {
-	struct pthread *curthread  = _get_curthread();
-	int ret;
+	struct pthread *curthread;
+	int ret, robust;
 
+	curthread  = _get_curthread();
 	if (!cvattach && m->m_flags & PMUTEX_FLAG_PRIVATE)
 		THR_CRITICAL_ENTER(curthread);
-	if (_thr_umutex_trylock2(&m->m_lock, TID(curthread)) == 0) {
-		enqueue_mutex(curthread, m);
-		ret = 0;
+	if (!rb_onlist)
+		robust = _mutex_enter_robust(curthread, m);
+	ret = _thr_umutex_trylock2(&m->m_lock, TID(curthread));
+	if (ret == 0 || ret == EOWNERDEAD) {
+		enqueue_mutex(curthread, m, ret);
+		if (ret == EOWNERDEAD)
+			m->m_lock.m_flags |= UMUTEX_NONCONSISTENT;
 	} else {
 		ret = mutex_lock_sleep(curthread, m, abstime);
 	}
-	if (ret && (m->m_flags & PMUTEX_FLAG_PRIVATE) && !cvattach)
+	if (!rb_onlist && robust)
+		_mutex_leave_robust(curthread, m);
+	if (ret != 0 && ret != EOWNERDEAD &&
+	    (m->m_flags & PMUTEX_FLAG_PRIVATE) != 0 && !cvattach)
 		THR_CRITICAL_LEAVE(curthread);
 	return (ret);
 }
@@ -613,7 +753,7 @@ __pthread_mutex_lock(pthread_mutex_t *mutex)
 	_thr_check_init();
 	ret = check_and_init_mutex(mutex, &m);
 	if (ret == 0)
-		ret = mutex_lock_common(m, NULL, 0);
+		ret = mutex_lock_common(m, NULL, false, false);
 	return (ret);
 }
 
@@ -627,7 +767,7 @@ __pthread_mutex_timedlock(pthread_mutex_t *mutex,
 	_thr_check_init();
 	ret = check_and_init_mutex(mutex, &m);
 	if (ret == 0)
-		ret = mutex_lock_common(m, abstime, 0);
+		ret = mutex_lock_common(m, abstime, false, false);
 	return (ret);
 }
 
@@ -644,16 +784,16 @@ _pthread_mutex_unlock(pthread_mutex_t *mutex)
 	} else {
 		mp = *mutex;
 	}
-	return (mutex_unlock_common(mp, 0, NULL));
+	return (mutex_unlock_common(mp, false, NULL));
 }
 
 int
-_mutex_cv_lock(struct pthread_mutex *m, int count)
+_mutex_cv_lock(struct pthread_mutex *m, int count, bool rb_onlist)
 {
-	int	error;
+	int error;
 
-	error = mutex_lock_common(m, NULL, 1);
-	if (error == 0)
+	error = mutex_lock_common(m, NULL, true, rb_onlist);
+	if (error == 0 || error == EOWNERDEAD)
 		m->m_count = count;
 	return (error);
 }
@@ -667,16 +807,17 @@ _mutex_cv_unlock(struct pthread_mutex *m, int *count, int *defer)
 	 */
 	*count = m->m_count;
 	m->m_count = 0;
-	(void)mutex_unlock_common(m, 1, defer);
+	(void)mutex_unlock_common(m, true, defer);
         return (0);
 }
 
 int
 _mutex_cv_attach(struct pthread_mutex *m, int count)
 {
-	struct pthread *curthread = _get_curthread();
+	struct pthread *curthread;
 
-	enqueue_mutex(curthread, m);
+	curthread = _get_curthread();
+	enqueue_mutex(curthread, m, 0);
 	m->m_count = count;
 	return (0);
 }
@@ -684,12 +825,12 @@ _mutex_cv_attach(struct pthread_mutex *m, int count)
 int
 _mutex_cv_detach(struct pthread_mutex *mp, int *recurse)
 {
-	struct pthread *curthread = _get_curthread();
-	int     defered;
-	int     error;
+	struct pthread *curthread;
+	int deferred, error;
 
+	curthread = _get_curthread();
 	if ((error = _mutex_owned(curthread, mp)) != 0)
-                return (error);
+		return (error);
 
 	/*
 	 * Clear the count in case this is a recursive mutex.
@@ -699,15 +840,15 @@ _mutex_cv_detach(struct pthread_mutex *mp, int *recurse)
 	dequeue_mutex(curthread, mp);
 
 	/* Will this happen in real-world ? */
-        if ((mp->m_flags & PMUTEX_FLAG_DEFERED) != 0) {
-		defered = 1;
-		mp->m_flags &= ~PMUTEX_FLAG_DEFERED;
+        if ((mp->m_flags & PMUTEX_FLAG_DEFERRED) != 0) {
+		deferred = 1;
+		mp->m_flags &= ~PMUTEX_FLAG_DEFERRED;
 	} else
-		defered = 0;
+		deferred = 0;
 
-	if (defered)  {
+	if (deferred)  {
 		_thr_wake_all(curthread->defer_waiters,
-				curthread->nwaiter_defer);
+		    curthread->nwaiter_defer);
 		curthread->nwaiter_defer = 0;
 	}
 	return (0);
@@ -716,7 +857,7 @@ _mutex_cv_detach(struct pthread_mutex *mp, int *recurse)
 static int
 mutex_self_trylock(struct pthread_mutex *m)
 {
-	int	ret;
+	int ret;
 
 	switch (PMUTEX_TYPE(m->m_flags)) {
 	case PTHREAD_MUTEX_ERRORCHECK:
@@ -746,7 +887,7 @@ static int
 mutex_self_lock(struct pthread_mutex *m, const struct timespec *abstime)
 {
 	struct timespec	ts1, ts2;
-	int	ret;
+	int ret;
 
 	switch (PMUTEX_TYPE(m->m_flags)) {
 	case PTHREAD_MUTEX_ERRORCHECK:
@@ -812,11 +953,11 @@ mutex_self_lock(struct pthread_mutex *m, const struct timespec *abstime)
 }
 
 static int
-mutex_unlock_common(struct pthread_mutex *m, int cv, int *mtx_defer)
+mutex_unlock_common(struct pthread_mutex *m, bool cv, int *mtx_defer)
 {
-	struct pthread *curthread = _get_curthread();
+	struct pthread *curthread;
 	uint32_t id;
-	int defered, error;
+	int deferred, error, robust;
 
 	if (__predict_false(m <= THR_MUTEX_DESTROYED)) {
 		if (m == THR_MUTEX_DESTROYED)
@@ -824,34 +965,39 @@ mutex_unlock_common(struct pthread_mutex *m, int cv, int *mtx_defer)
 		return (EPERM);
 	}
 
+	curthread = _get_curthread();
 	id = TID(curthread);
 
 	/*
 	 * Check if the running thread is not the owner of the mutex.
 	 */
-	if (__predict_false(m->m_owner != id))
+	if (__predict_false(PMUTEX_OWNER_ID(m) != id))
 		return (EPERM);
 
 	error = 0;
-	if (__predict_false(
-		PMUTEX_TYPE(m->m_flags) == PTHREAD_MUTEX_RECURSIVE &&
-		m->m_count > 0)) {
+	if (__predict_false(PMUTEX_TYPE(m->m_flags) ==
+	    PTHREAD_MUTEX_RECURSIVE && m->m_count > 0)) {
 		m->m_count--;
 	} else {
-		if ((m->m_flags & PMUTEX_FLAG_DEFERED) != 0) {
-			defered = 1;
-			m->m_flags &= ~PMUTEX_FLAG_DEFERED;
+		if ((m->m_flags & PMUTEX_FLAG_DEFERRED) != 0) {
+			deferred = 1;
+			m->m_flags &= ~PMUTEX_FLAG_DEFERRED;
         	} else
-			defered = 0;
+			deferred = 0;
 
+		robust = _mutex_enter_robust(curthread, m);
 		dequeue_mutex(curthread, m);
 		error = _thr_umutex_unlock2(&m->m_lock, id, mtx_defer);
-
-		if (mtx_defer == NULL && defered)  {
-			_thr_wake_all(curthread->defer_waiters,
-				curthread->nwaiter_defer);
-			curthread->nwaiter_defer = 0;
+		if (deferred)  {
+			if (mtx_defer == NULL) {
+				_thr_wake_all(curthread->defer_waiters,
+				    curthread->nwaiter_defer);
+				curthread->nwaiter_defer = 0;
+			} else
+				*mtx_defer = 1;
 		}
+		if (robust)
+			_mutex_leave_robust(curthread, m);
 	}
 	if (!cv && m->m_flags & PMUTEX_FLAG_PRIVATE)
 		THR_CRITICAL_LEAVE(curthread);
@@ -887,7 +1033,7 @@ _pthread_mutex_setprioceiling(pthread_mutex_t *mutex,
 	struct pthread *curthread;
 	struct pthread_mutex *m, *m1, *m2;
 	struct mutex_queue *q, *qp;
-	int ret;
+	int qidx, ret;
 
 	if (*mutex == THR_PSHARED_PTR) {
 		m = __thr_pshared_offpage(mutex, 0);
@@ -907,14 +1053,15 @@ _pthread_mutex_setprioceiling(pthread_mutex_t *mutex,
 		return (ret);
 
 	curthread = _get_curthread();
-	if (m->m_owner == TID(curthread)) {
+	if (PMUTEX_OWNER_ID(m) == TID(curthread)) {
 		mutex_assert_is_owned(m);
 		m1 = TAILQ_PREV(m, mutex_queue, m_qe);
 		m2 = TAILQ_NEXT(m, m_qe);
 		if ((m1 != NULL && m1->m_lock.m_ceilings[0] > (u_int)ceiling) ||
 		    (m2 != NULL && m2->m_lock.m_ceilings[0] < (u_int)ceiling)) {
-			q = &curthread->mq[TMQ_NORM_PP];
-			qp = &curthread->mq[TMQ_NORM_PP_PRIV];
+			qidx = mutex_qidx(m);
+			q = &curthread->mq[qidx];
+			qp = &curthread->mq[qidx + 1];
 			TAILQ_REMOVE(q, m, m_qe);
 			if (!is_pshared_mutex(m))
 				TAILQ_REMOVE(qp, m, m_pqe);
@@ -1009,18 +1156,45 @@ _pthread_mutex_isowned_np(pthread_mutex_t *mutex)
 		if (m <= THR_MUTEX_DESTROYED)
 			return (0);
 	}
-	return (m->m_owner == TID(_get_curthread()));
+	return (PMUTEX_OWNER_ID(m) == TID(_get_curthread()));
 }
 
 int
 _mutex_owned(struct pthread *curthread, const struct pthread_mutex *mp)
 {
+
 	if (__predict_false(mp <= THR_MUTEX_DESTROYED)) {
 		if (mp == THR_MUTEX_DESTROYED)
 			return (EINVAL);
 		return (EPERM);
 	}
-	if (mp->m_owner != TID(curthread))
+	if (PMUTEX_OWNER_ID(mp) != TID(curthread))
 		return (EPERM);
 	return (0);                  
 }
+
+int
+_pthread_mutex_consistent(pthread_mutex_t *mutex)
+{
+	struct pthread_mutex *m;
+	struct pthread *curthread;
+
+	if (*mutex == THR_PSHARED_PTR) {
+		m = __thr_pshared_offpage(mutex, 0);
+		if (m == NULL)
+			return (EINVAL);
+		shared_mutex_init(m, NULL);
+	} else {
+		m = *mutex;
+		if (m <= THR_MUTEX_DESTROYED)
+			return (EINVAL);
+	}
+	curthread = _get_curthread();
+	if ((m->m_lock.m_flags & (UMUTEX_ROBUST | UMUTEX_NONCONSISTENT)) !=
+	    (UMUTEX_ROBUST | UMUTEX_NONCONSISTENT))
+		return (EINVAL);
+	if (PMUTEX_OWNER_ID(m) != TID(curthread))
+		return (EPERM);
+	m->m_lock.m_flags &= ~UMUTEX_NONCONSISTENT;
+	return (0);
+}