diff --git a/nptl/Makefile b/nptl/Makefile
index 9d5738f..77deb74 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -295,7 +295,8 @@ tests = tst-typesizes \
 	tst-initializers1 $(addprefix tst-initializers1-,\
 			    c89 gnu89 c99 gnu99 c11 gnu11) \
 	tst-bad-schedattr \
-	tst-thread_local1 tst-mutex-errorcheck tst-robust10
+	tst-thread_local1 tst-mutex-errorcheck tst-robust10 \
+	tst-create-detached
 xtests = tst-setuid1 tst-setuid1-static tst-setuid2 \
 	tst-mutexpp1 tst-mutexpp6 tst-mutexpp10
 test-srcs = tst-oddstacklimit
diff --git a/nptl/createthread.c b/nptl/createthread.c
index 345f425..6c67b7e 100644
--- a/nptl/createthread.c
+++ b/nptl/createthread.c
@@ -25,16 +25,14 @@
 
 static int
 create_thread (struct pthread *pd, const struct pthread_attr *attr,
-	       bool stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
+	       bool *stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
 {
   /* If the implementation needs to do some tweaks to the thread after
      it has been created at the OS level, it can set STOPPED_START here.  */
 
-  pd->stopped_start = stopped_start;
-  if (__glibc_unlikely (stopped_start))
-    /* We make sure the thread does not run far by forcing it to get a
-       lock.  We lock it here too so that the new thread cannot continue
-       until we tell it to.  */
+  pd->stopped_start = *stopped_start;
+  if (__glibc_unlikely (*stopped_start))
+    /* See CONCURRENCY NOTES in nptl/pthread_create.c.  */
     lll_lock (pd->lock, LLL_PRIVATE);
 
   return ENOSYS;
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 867e347..9882882 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -54,25 +54,136 @@ unsigned int __nptl_nthreads = 1;
 /* Code to allocate and deallocate a stack.  */
 #include "allocatestack.c"
 
-/* createthread.c defines this function, and two macros:
+/* CONCURRENCY NOTES:
+
+   Understanding who is the owner of the 'struct pthread' or 'PD'
+   (refers to the value of the 'struct pthread *pd' function argument)
+   is critically important in determining exactly which operations are
+   allowed and which are not and when, particularly when it comes to the
+   implementation of pthread_create, pthread_join, pthread_detach, and
+   other functions which all operate on PD.
+
+   The owner of PD is responsible for freeing the final resources
+   associated with PD, and may examine the memory underlying PD at any
+   point in time until it frees it back to the OS or to reuse by the
+   runtime.
+
+   The thread which calls pthread_create is called the creating thread.
+   The creating thread begins as the owner of PD.
+
+   During startup the new thread may examine PD in coordination with the
+   owner thread (which may be itself).
+
+   The four cases of ownership transfer are:
+
+   (1) Ownership of PD is released to the process (all threads may use it)
+       after the new thread starts in a joinable state
+       i.e. pthread_create returns a usable pthread_t.
+
+   (2) Ownership of PD is released to the new thread starting in a detached
+       state.
+
+   (3) Ownership of PD is dynamically released to a running thread via
+       pthread_detach.
+
+   (4) Ownership of PD is acquired by the thread which calls pthread_join.
+
+   Implementation notes:
+
+   The PD->stopped_start and thread_ran variables are used to determine
+   exactly which of the four ownership states we are in and therefore
+   what actions can be taken.  For example after (2) we cannot read or
+   write from PD anymore since the thread may no longer exist and the
+   memory may be unmapped.  The most complicated cases happen during
+   thread startup:
+
+   (a) If the created thread is in a detached (PTHREAD_CREATE_DETACHED),
+       or joinable (default PTHREAD_CREATE_JOINABLE) state and
+       STOPPED_START is true, then the creating thread has ownership of
+       PD until the PD->lock is released by pthread_create.
+
+   (b) If the created thread is in a detached state
+       (PTHREAD_CREATED_DETACHED), and STOPPED_START is false, then the
+       creating thread has ownership of PD until the OS thread creation
+       routine returns without error.
+
+   (c) If the detached thread setup failed and THREAD_RAN is true, then
+       the creating thread releases ownership to the new thread by
+       sending a cancellation signal.
+
+   (d) If the joinable thread setup failed and THREAD_RAN is true, then
+       then the creating thread retains ownership of PD and must cleanup
+       state.  Ownership cannot be released to the process via the
+       return of pthread_create since a non-zero result entails PD is
+       undefined and therefore cannot be joined to free the resources.
+       We privately call pthread_join on the thread to finish handling
+       the resource shutdown (Or at least we should, see bug 19511).
+
+   (e) If the thread creation failed and THREAD_RAN is false, then the
+       creating thread retains ownership of PD and must cleanup state.
+       No waiting for the new thread is required because it never
+       started.
+
+   The nptl_db interface:
+
+   The interface with nptl_db requires that we enqueue PD into a linked
+   list and then call a function which the debugger will trap.  The PD
+   will then be dequeued and control returned to the thread.  The caller
+   at the time must have ownership of PD and such ownership remains
+   after control returns to thread. The enqueued PD is removed from the
+   linked list by the nptl_db callback td_thr_event_getmsg.  The debugger
+   must ensure that the thread does not resume execution, otherwise
+   ownership of PD may be lost and examining PD will not be possible.
+
+   Note that the GNU Debugger as of (December 10th 2015) commit
+   c2c2a31fdb228d41ce3db62b268efea04bd39c18 no longer uses
+   td_thr_event_getmsg and several other related nptl_db interfaces. The
+   principal reason for this is that nptl_db does not support non-stop
+   mode where other threads can run concurrently and modify runtime
+   structures currently in use by the debugger and the nptl_db
+   interface.
+
+   Axioms:
+
+   * The create_thread function can never set stopped_start to false.
+   * The created thread can read stopped_start but never write to it.
+   * The variable thread_ran is set some time after the OS thread
+     creation routine returnds, how much time after the thread is created
+     is unspecified.
+
+*/
+
+/* CREATE THREAD NOTES:
+
+   createthread.c defines the create_thread function, and two macros:
    START_THREAD_DEFN and START_THREAD_SELF (see below).
 
-   create_thread is obliged to initialize PD->stopped_start.  It
-   should be true if the STOPPED_START parameter is true, or if
-   create_thread needs the new thread to synchronize at startup for
-   some other implementation reason.  If PD->stopped_start will be
-   true, then create_thread is obliged to perform the operation
-   "lll_lock (PD->lock, LLL_PRIVATE)" before starting the thread.
+   create_thread must initialize PD->stopped_start.  It should be true
+   if the STOPPED_START parameter is true, or if create_thread needs the
+   new thread to synchronize at startup for some other implementation
+   reason.  If STOPPED_START will be true, then create_thread is obliged
+   to lock PD->lock before starting the thread.  Then pthread_create
+   unlocks PD->lock which synchronizes-with START_THREAD_DEFN in the
+   child thread which does an acquire/release of PD->lock as the last
+   action before calling the user entry point.  The goal of all of this
+   is to ensure that the required initial thread attributes are applied
+   (by the creating thread) before the new thread runs user code.  Note
+   that the the functions pthread_getschedparam, pthread_setschedparam,
+   pthread_setschedprio, __pthread_tpp_change_priority, and
+   __pthread_current_priority reuse the same lock, PD->lock, for a
+   similar purpose e.g. synchronizing the setting of similar thread
+   attributes.  These functions are never be called before the thread is
+   created, so don't participate in startup syncronization, but given
+   that the lock is present already and in the unlocked state, reusing
+   it saves space.
 
    The return value is zero for success or an errno code for failure.
    If the return value is ENOMEM, that will be translated to EAGAIN,
    so create_thread need not do that.  On failure, *THREAD_RAN should
    be set to true iff the thread actually started up and then got
-   cancelled before calling user code (*PD->start_routine), in which
-   case it is responsible for doing its own cleanup.  */
-
+   cancelled before calling user code (*PD->start_routine).  */
 static int create_thread (struct pthread *pd, const struct pthread_attr *attr,
-			  bool stopped_start, STACK_VARIABLES_PARMS,
+			  bool *stopped_start, STACK_VARIABLES_PARMS,
 			  bool *thread_ran);
 
 #include <createthread.c>
@@ -314,12 +425,19 @@ START_THREAD_DEFN
       /* Store the new cleanup handler info.  */
       THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);
 
+      /* We are either in (a) or (b), and in either case we either own
+         PD already (2) or are about to own PD (1), and so our only
+	 restriction would be that we can't free PD until we know we
+	 have ownership (see CONCURRENCY NOTES above).  */
       if (__glibc_unlikely (pd->stopped_start))
 	{
 	  int oldtype = CANCEL_ASYNC ();
 
 	  /* Get the lock the parent locked to force synchronization.  */
 	  lll_lock (pd->lock, LLL_PRIVATE);
+
+	  /* We have ownership of PD now.  */
+
 	  /* And give it up right away.  */
 	  lll_unlock (pd->lock, LLL_PRIVATE);
 
@@ -378,7 +496,8 @@ START_THREAD_DEFN
 							   pd, pd->nextevent));
 	    }
 
-	  /* Now call the function to signal the event.  */
+	  /* Now call the function which signals the event.  See
+	     CONCURRENCY NOTES for the nptl_db interface comments.  */
 	  __nptl_death_event ();
 	}
     }
@@ -642,19 +761,28 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
      that cares whether the thread count is correct.  */
   atomic_increment (&__nptl_nthreads);
 
-  bool thread_ran = false;
+  /* Our local value of stopped_start and thread_ran can be accessed at
+     any time. The PD->stopped_start may only be accessed if we have
+     ownership of PD (see CONCURRENCY NOTES above).  */
+  bool stopped_start = false; bool thread_ran = false;
 
   /* Start the thread.  */
   if (__glibc_unlikely (report_thread_creation (pd)))
     {
-      /* Create the thread.  We always create the thread stopped
-	 so that it does not get far before we tell the debugger.  */
-      retval = create_thread (pd, iattr, true, STACK_VARIABLES_ARGS,
-			      &thread_ran);
+      stopped_start = true;
+
+      /* We always create the thread stopped at startup so we can
+	 notify the debugger.  */
+      retval = create_thread (pd, iattr, &stopped_start,
+			      STACK_VARIABLES_ARGS, &thread_ran);
       if (retval == 0)
 	{
-	  /* create_thread should have set this so that the logic below can
-	     test it.  */
+	  /* We retain ownership of PD until (a) (see CONCURRENCY NOTES
+	     above).  */
+
+	  /* Assert stopped_start is true in both our local copy and the
+	     PD copy.  */
+	  assert (stopped_start);
 	  assert (pd->stopped_start);
 
 	  /* Now fill in the information about the new thread in
@@ -671,26 +799,30 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
 						       pd, pd->nextevent)
 		 != 0);
 
-	  /* Now call the function which signals the event.  */
+	  /* Now call the function which signals the event.  See
+	     CONCURRENCY NOTES for the nptl_db interface comments.  */
 	  __nptl_create_event ();
 	}
     }
   else
-    retval = create_thread (pd, iattr, false, STACK_VARIABLES_ARGS,
-			    &thread_ran);
+    retval = create_thread (pd, iattr, &stopped_start,
+			    STACK_VARIABLES_ARGS, &thread_ran);
 
   if (__glibc_unlikely (retval != 0))
     {
-      /* If thread creation "failed", that might mean that the thread got
-	 created and ran a little--short of running user code--but then
-	 create_thread cancelled it.  In that case, the thread will do all
-	 its own cleanup just like a normal thread exit after a successful
-	 creation would do.  */
-
       if (thread_ran)
-	assert (pd->stopped_start);
+	/* State (c) or (d) and we may not have PD ownership (see
+	   CONCURRENCY NOTES above).  We can assert that STOPPED_START
+	   must have been true because thread creation didn't fail, but
+	   thread attribute setting did.  */
+	/* See bug 19511 which explains why doing nothing here is a
+	   resource leak for a joinable thread.  */
+	assert (stopped_start);
       else
 	{
+	  /* State (e) and we have ownership of PD (see CONCURRENCY
+	     NOTES above).  */
+
 	  /* Oops, we lied for a second.  */
 	  atomic_decrement (&__nptl_nthreads);
 
@@ -710,10 +842,14 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
     }
   else
     {
-      if (pd->stopped_start)
-	/* The thread blocked on this lock either because we're doing TD_CREATE
-	   event reporting, or for some other reason that create_thread chose.
-	   Now let it run free.  */
+      /* We don't know if we have PD ownership.  Once we check the local
+         stopped_start we'll know if we're in state (a) or (b) (see
+	 CONCURRENCY NOTES above).  */
+      if (stopped_start)
+	/* State (a), we own PD. The thread blocked on this lock either
+	   because we're doing TD_CREATE event reporting, or for some
+	   other reason that create_thread chose.  Now let it run
+	   free.  */
 	lll_unlock (pd->lock, LLL_PRIVATE);
 
       /* We now have for sure more than one thread.  The main thread might
diff --git a/nptl/pthread_getschedparam.c b/nptl/pthread_getschedparam.c
index 5c49afa..9914b9d 100644
--- a/nptl/pthread_getschedparam.c
+++ b/nptl/pthread_getschedparam.c
@@ -35,6 +35,7 @@ __pthread_getschedparam (pthread_t threadid, int *policy,
 
   int result = 0;
 
+  /* See CREATE THREAD NOTES in nptl/pthread_create.c.  */
   lll_lock (pd->lock, LLL_PRIVATE);
 
   /* The library is responsible for maintaining the values at all
diff --git a/nptl/pthread_setschedparam.c b/nptl/pthread_setschedparam.c
index 459a8cf..a6539b3 100644
--- a/nptl/pthread_setschedparam.c
+++ b/nptl/pthread_setschedparam.c
@@ -36,6 +36,7 @@ __pthread_setschedparam (pthread_t threadid, int policy,
 
   int result = 0;
 
+  /* See CREATE THREAD NOTES in nptl/pthread_create.c.  */
   lll_lock (pd->lock, LLL_PRIVATE);
 
   struct sched_param p;
diff --git a/nptl/pthread_setschedprio.c b/nptl/pthread_setschedprio.c
index 8d78d64..b83d2fb 100644
--- a/nptl/pthread_setschedprio.c
+++ b/nptl/pthread_setschedprio.c
@@ -38,6 +38,7 @@ pthread_setschedprio (pthread_t threadid, int prio)
   struct sched_param param;
   param.sched_priority = prio;
 
+  /* See CREATE THREAD NOTES in nptl/pthread_create.c.  */
   lll_lock (pd->lock, LLL_PRIVATE);
 
   /* If the thread should have higher priority because of some
diff --git a/nptl/tpp.c b/nptl/tpp.c
index f2e6905..57eb026 100644
--- a/nptl/tpp.c
+++ b/nptl/tpp.c
@@ -114,6 +114,7 @@ __pthread_tpp_change_priority (int previous_prio, int new_prio)
   if (priomax == newpriomax)
     return 0;
 
+  /* See CREATE THREAD NOTES in nptl/pthread_create.c.  */
   lll_lock (self->lock, LLL_PRIVATE);
 
   tpp->priomax = newpriomax;
@@ -165,6 +166,7 @@ __pthread_current_priority (void)
 
   int result = 0;
 
+  /* See CREATE THREAD NOTES in nptl/pthread_create.c.  */
   lll_lock (self->lock, LLL_PRIVATE);
 
   if ((self->flags & ATTR_FLAG_SCHED_SET) == 0)
diff --git a/nptl/tst-create-detached.c b/nptl/tst-create-detached.c
new file mode 100644
index 0000000..ea93e44
--- /dev/null
+++ b/nptl/tst-create-detached.c
@@ -0,0 +1,137 @@
+/* Bug 20116: Test rapid creation of detached threads.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+/* The goal of the test is to trigger a failure if the parent touches
+   any part of the thread descriptor after the detached thread has
+   exited.  We test this by creating many detached threads with large
+   stacks.  The stacks quickly fill the the stack cache and subsequent
+   threads will start to cause the thread stacks to be immediately
+   unmapped to satisfy the stack cache max.  With the stacks being
+   unmapped the parent's read of any part of the thread descriptor will
+   trigger a segfault.  That segfault is what we are trying to cause,
+   since any segfault is a defect in the implementation.  */
+
+#include <pthread.h>
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <sys/resource.h>
+#include <support/xthread.h>
+
+/* Number of threads to create.  */
+enum { threads_to_create = 100000 };
+
+/* Number of threads which should spawn other threads.  */
+enum { creator_threads  = 2 };
+
+/* Counter of threads created so far.  This is incremented by all the
+   running creator threads.  */
+static unsigned threads_created;
+
+/* Thread callback which does nothing, so that the thread exits
+   immediatedly.  */
+static void *
+do_nothing (void *arg)
+{
+  return NULL;
+}
+
+/* Attribute indicating that the thread should be created in a detached
+   fashion.  */
+static pthread_attr_t detached;
+
+/* Barrier to synchronize initialization.  */
+static pthread_barrier_t barrier;
+
+static void *
+creator_thread (void *arg)
+{
+  int ret;
+  xpthread_barrier_wait (&barrier);
+
+  while (true)
+    {
+      pthread_t thr;
+      /* Thread creation will fail if the kernel does not free old
+	 threads quickly enough, so we do not report errors.  */
+      ret = pthread_create (&thr, &detached, do_nothing, NULL);
+      if (ret == 0 && __atomic_add_fetch (&threads_created, 1, __ATOMIC_SEQ_CST)
+          >= threads_to_create)
+        break;
+    }
+
+  return NULL;
+}
+
+static int
+do_test (void)
+{
+  /* Limit the size of the process, so that memory allocation will
+     fail without impacting the entire system.  */
+  {
+    struct rlimit limit;
+    if (getrlimit (RLIMIT_AS, &limit) != 0)
+      {
+        printf ("FAIL: getrlimit (RLIMIT_AS) failed: %m\n");
+        return 1;
+      }
+    /* This limit, 800MB, is just a heuristic. Any value can be
+       picked.  */
+    long target = 800 * 1024 * 1024;
+    if (limit.rlim_cur == RLIM_INFINITY || limit.rlim_cur > target)
+      {
+        limit.rlim_cur = target;
+        if (setrlimit (RLIMIT_AS, &limit) != 0)
+          {
+            printf ("FAIL: setrlimit (RLIMIT_AS) failed: %m\n");
+            return 1;
+          }
+      }
+  }
+
+  xpthread_attr_init (&detached);
+
+  xpthread_attr_setdetachstate (&detached, PTHREAD_CREATE_DETACHED);
+
+  /* A large thread stack seems beneficial for reproducing a race
+     condition in detached thread creation.  The goal is to reach the
+     limit of the runtime thread stack cache such that the detached
+     thread's stack is unmapped after exit and causes a segfault when
+     the parent reads the thread descriptor data stored on the the
+     unmapped stack.  */
+  xpthread_attr_setstacksize (&detached, 16 * 1024 * 1024);
+
+  xpthread_barrier_init (&barrier, NULL, creator_threads);
+
+  pthread_t threads[creator_threads];
+
+  for (int i = 0; i < creator_threads; ++i)
+    threads[i] = xpthread_create (NULL, creator_thread, NULL);
+
+  for (int i = 0; i < creator_threads; ++i)
+    xpthread_join (threads[i]);
+
+  xpthread_attr_destroy (&detached);
+
+  xpthread_barrier_destroy (&barrier);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/Makefile b/support/Makefile
index 7114855..af285d6 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -62,6 +62,10 @@ libsupport-routines = \
   xmalloc \
   xmemstream \
   xpoll \
+  xpthread_attr_destroy \
+  xpthread_attr_init \
+  xpthread_attr_setdetachstate \
+  xpthread_attr_setstacksize \
   xpthread_barrier_destroy \
   xpthread_barrier_init \
   xpthread_barrier_wait \
diff --git a/support/xpthread_attr_destroy.c b/support/xpthread_attr_destroy.c
new file mode 100644
index 0000000..664c809
--- /dev/null
+++ b/support/xpthread_attr_destroy.c
@@ -0,0 +1,26 @@
+/* pthread_attr_destroy with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_destroy (pthread_attr_t *attr)
+{
+  xpthread_check_return ("pthread_attr_destroy",
+			 pthread_attr_destroy (attr));
+}
diff --git a/support/xpthread_attr_init.c b/support/xpthread_attr_init.c
new file mode 100644
index 0000000..2e30ade
--- /dev/null
+++ b/support/xpthread_attr_init.c
@@ -0,0 +1,25 @@
+/* pthread_attr_init with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_init (pthread_attr_t *attr)
+{
+  xpthread_check_return ("pthread_attr_init", pthread_attr_init (attr));
+}
diff --git a/support/xpthread_attr_setdetachstate.c b/support/xpthread_attr_setdetachstate.c
new file mode 100644
index 0000000..b544dba
--- /dev/null
+++ b/support/xpthread_attr_setdetachstate.c
@@ -0,0 +1,27 @@
+/* pthread_attr_setdetachstate with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_setdetachstate (pthread_attr_t *attr, int detachstate)
+{
+  xpthread_check_return ("pthread_attr_setdetachstate",
+			 pthread_attr_setdetachstate (attr,
+						      detachstate));
+}
diff --git a/support/xpthread_attr_setstacksize.c b/support/xpthread_attr_setstacksize.c
new file mode 100644
index 0000000..02d0631
--- /dev/null
+++ b/support/xpthread_attr_setstacksize.c
@@ -0,0 +1,26 @@
+/* pthread_attr_setstacksize with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_setstacksize (pthread_attr_t *attr, size_t stacksize)
+{
+  xpthread_check_return ("pthread_attr_setstacksize",
+			 pthread_attr_setstacksize (attr, stacksize));
+}
diff --git a/support/xthread.h b/support/xthread.h
index e5c896b..75e3da3 100644
--- a/support/xthread.h
+++ b/support/xthread.h
@@ -52,6 +52,12 @@ void xpthread_detach (pthread_t thr);
 void xpthread_cancel (pthread_t thr);
 void *xpthread_join (pthread_t thr);
 void xpthread_once (pthread_once_t *guard, void (*func) (void));
+void xpthread_attr_destroy (pthread_attr_t *attr);
+void xpthread_attr_init (pthread_attr_t *attr);
+void xpthread_attr_setdetachstate (pthread_attr_t *attr,
+				   int detachstate);
+void xpthread_attr_setstacksize (pthread_attr_t *attr,
+				 size_t stacksize);
 
 /* This function returns non-zero if pthread_barrier_wait returned
    PTHREAD_BARRIER_SERIAL_THREAD.  */
diff --git a/sysdeps/nacl/createthread.c b/sysdeps/nacl/createthread.c
index c09516a..87466dc 100644
--- a/sysdeps/nacl/createthread.c
+++ b/sysdeps/nacl/createthread.c
@@ -32,15 +32,13 @@ static void start_thread (void) __attribute__ ((noreturn));
 
 static int
 create_thread (struct pthread *pd, const struct pthread_attr *attr,
-	       bool stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
+	       bool *stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
 {
   pd->tid = __nacl_get_tid (pd);
 
-  pd->stopped_start = stopped_start;
-  if (__glibc_unlikely (stopped_start))
-    /* We make sure the thread does not run far by forcing it to get a
-       lock.  We lock it here too so that the new thread cannot continue
-       until we tell it to.  */
+  pd->stopped_start = *stopped_start;
+  if (__glibc_unlikely (*stopped_start))
+    /* See CONCURRENCY NOTES in nptl/pthread_create.c.  */
     lll_lock (pd->lock, LLL_PRIVATE);
 
   TLS_DEFINE_INIT_TP (tp, pd);
diff --git a/sysdeps/unix/sysv/linux/createthread.c b/sysdeps/unix/sysv/linux/createthread.c
index 1c1341b..fe3a3fe 100644
--- a/sysdeps/unix/sysv/linux/createthread.c
+++ b/sysdeps/unix/sysv/linux/createthread.c
@@ -46,7 +46,7 @@ static int start_thread (void *arg) __attribute__ ((noreturn));
 
 static int
 create_thread (struct pthread *pd, const struct pthread_attr *attr,
-	       bool stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
+	       bool *stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
 {
   /* Determine whether the newly created threads has to be started
      stopped since we have to set the scheduling parameters or set the
@@ -54,13 +54,11 @@ create_thread (struct pthread *pd, const struct pthread_attr *attr,
   if (attr != NULL
       && (__glibc_unlikely (attr->cpuset != NULL)
 	  || __glibc_unlikely ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)))
-    stopped_start = true;
+    *stopped_start = true;
 
-  pd->stopped_start = stopped_start;
-  if (__glibc_unlikely (stopped_start))
-    /* We make sure the thread does not run far by forcing it to get a
-       lock.  We lock it here too so that the new thread cannot continue
-       until we tell it to.  */
+  pd->stopped_start = *stopped_start;
+  if (__glibc_unlikely (*stopped_start))
+    /* See CONCURRENCY NOTES in nptl/pthread_creat.c.  */
     lll_lock (pd->lock, LLL_PRIVATE);
 
   /* We rely heavily on various flags the CLONE function understands:
@@ -117,7 +115,7 @@ create_thread (struct pthread *pd, const struct pthread_attr *attr,
       /* Set the affinity mask if necessary.  */
       if (attr->cpuset != NULL)
 	{
-	  assert (stopped_start);
+	  assert (*stopped_start);
 
 	  res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid,
 				  attr->cpusetsize, attr->cpuset);
@@ -140,7 +138,7 @@ create_thread (struct pthread *pd, const struct pthread_attr *attr,
       /* Set the scheduling parameters.  */
       if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)
 	{
-	  assert (stopped_start);
+	  assert (*stopped_start);
 
 	  res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid,
 				  pd->schedpolicy, &pd->schedparam);
