Add and use new glibc-internal futex API.

This adds new functions for futex operations, starting with wait,
abstimed_wait, reltimed_wait, wake.  They add documentation and error
checking according to the current draft of the Linux kernel futex manpage.

Waiting with absolute or relative timeouts is split into separate functions.
This allows for removing a few cases of code duplication in pthreads code,
which uses absolute timeouts; also, it allows us to put platform-specific
code to go from an absolute to a relative timeout into the platform-specific
futex abstractions..

Futex operations that can be canceled are also split out into separate
functions suffixed by "_cancelable".

There are separate versions for both Linux and NaCl; while they currently
differ only slightly, my expectation is that the separate versions of
lowlevellock-futex.h will eventually be merged into futex-internal.h
when we get to move the lll_ functions over to the new futex API.

15 files changed, 751 insertions, 174 deletions

diff --git a/sysdeps/nacl/exit-thread.h b/sysdeps/nacl/exit-thread.h
index c809405cf1..915f93dd0d 100644
--- a/sysdeps/nacl/exit-thread.h
+++ b/sysdeps/nacl/exit-thread.h
@@ -18,7 +18,7 @@
 
 #include <assert.h>
 #include <atomic.h>
-#include <lowlevellock.h>
+#include <futex-internal.h>
 #include <nacl-interfaces.h>
 #include <nptl/pthreadP.h>
 
@@ -64,7 +64,7 @@ __exit_thread (void)
       assert (NACL_EXITING_TID > 0);
 
       atomic_store_relaxed (&pd->tid, NACL_EXITING_TID);
-      lll_futex_wake (&pd->tid, 1, LLL_PRIVATE);
+      futex_wake ((unsigned int *) &pd->tid, 1, FUTEX_PRIVATE);
     }
 
   /* This clears PD->tid some time after the thread stack can never
diff --git a/sysdeps/nacl/futex-internal.h b/sysdeps/nacl/futex-internal.h
new file mode 100644
index 0000000000..593bb9d9bf
--- /dev/null
+++ b/sysdeps/nacl/futex-internal.h
@@ -0,0 +1,248 @@
+/* futex operations for glibc-internal use.  NaCl version.
+   Copyright (C) 2014-2015 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/>.  */
+
+#ifndef FUTEX_INTERNAL_H
+#define FUTEX_INTERNAL_H
+
+#include <sysdeps/nptl/futex-internal.h>
+#include <errno.h>
+#include <lowlevellock-futex.h>
+#include <nacl-interfaces.h>
+#include <nptl/pthreadP.h>
+
+/* See sysdeps/nptl/futex-internal.h for documentation; this file only
+   contains NaCl-specific comments.
+
+   There is no support yet for shared futexes nor for exact relative
+   timeouts.  */
+
+/* See sysdeps/nptl/futex-internal.h for constraints on the value of the
+   FUTEX_PRIVATE and FUTEX_SHARED constants.
+   Shared futexes are not yet supported, and we never allow clients to
+   actually request shared futexes.  Therefore, we do not need a different
+   value.  */
+#undef FUTEX_SHARED
+#define FUTEX_SHARED  FUTEX_PRIVATE
+
+/* FUTEX_SHARED is not yet supported.  */
+static __always_inline int
+futex_supports_pshared (int pshared)
+{
+  if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
+    return 0;
+  else if (pshared == PTHREAD_PROCESS_SHARED)
+    return ENOTSUP;
+  else
+    return EINVAL;
+}
+
+/* Relative timeouts are only emulated via absolute timeouts using the
+   system clock.  */
+static __always_inline bool
+futex_supports_exact_relative_timeouts (void)
+{
+  return false;
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_wait (unsigned int *futex_word, unsigned int expected, int private)
+{
+  int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+      return -err;
+
+    case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
+		       int private)
+{
+  int oldtype;
+  oldtype = __pthread_enable_asynccancel ();
+  int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+      return -err;
+
+    case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
+		     const struct timespec *reltime, int private)
+{
+  int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_reltimed_wait_cancelable (unsigned int *futex_word,
+				unsigned int expected,
+			        const struct timespec *reltime, int private)
+{
+  int oldtype;
+  oldtype = __pthread_enable_asynccancel ();
+  int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
+		     const struct timespec *abstime, int private)
+{
+  int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) futex_word,
+					     expected, abstime);
+  switch (err)
+    {
+    case 0:
+    case EAGAIN:
+    case EINTR:
+    case ETIMEDOUT:
+      return err;
+
+    case EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case EINVAL: /* Either due to wrong alignment or due to the timeout not
+		    being normalized.  Must have been caused by a glibc or
+		    application bug.  */
+    case ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_abstimed_wait_cancelable (unsigned int *futex_word,
+				unsigned int expected,
+			        const struct timespec *abstime, int private)
+{
+  int oldtype;
+  oldtype = __pthread_enable_asynccancel ();
+  int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) futex_word,
+					     expected, abstime);
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case EAGAIN:
+    case EINTR:
+    case ETIMEDOUT:
+      return err;
+
+    case EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case EINVAL: /* Either due to wrong alignment or due to the timeout not
+		    being normalized.  Must have been caused by a glibc or
+		    application bug.  */
+    case ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline void
+futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
+{
+  int res = lll_futex_wake (futex_word, processes_to_wake, private);
+  /* No error.  Ignore the number of woken processes.  */
+  if (res >= 0)
+    return;
+  switch (res)
+    {
+    case -EFAULT: /* Could have happened due to memory reuse.  */
+    case -EINVAL: /* Could be either due to incorrect alignment (a bug in
+		     glibc or in the application) or due to memory being
+		     reused for a PI futex.  We cannot distinguish between the
+		     two causes, and one of them is correct use, so we do not
+		     act in this case.  */
+      return;
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+#endif  /* futex-internal.h */
diff --git a/sysdeps/nptl/aio_misc.h b/sysdeps/nptl/aio_misc.h
index d5d1c08d0f..4a6ebfc9b3 100644
--- a/sysdeps/nptl/aio_misc.h
+++ b/sysdeps/nptl/aio_misc.h
@@ -22,14 +22,14 @@
 
 #include <assert.h>
 #include <nptl/pthreadP.h>
-#include <lowlevellock.h>
+#include <futex-internal.h>
 
 #define DONT_NEED_AIO_MISC_COND	1
 
 #define AIO_MISC_NOTIFY(waitlist) \
   do {									      \
     if (*waitlist->counterp > 0 && --*waitlist->counterp == 0)		      \
-      lll_futex_wake (waitlist->counterp, 1, LLL_PRIVATE);		      \
+      futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE);     \
   } while (0)
 
 #define AIO_MISC_WAIT(result, futex, timeout, cancel)			      \
@@ -48,9 +48,9 @@
 	int status;							      \
 	do								      \
 	  {								      \
-	    status = lll_futex_timed_wait (futexaddr, oldval, timeout,	      \
-					   LLL_PRIVATE);		      \
-	    if (status != -EWOULDBLOCK)					      \
+	    status = futex_reltimed_wait ((unsigned int *) futexaddr, oldval, \
+					  timeout, FUTEX_PRIVATE);	      \
+	    if (status != EAGAIN)					      \
 	      break;							      \
 									      \
 	    oldval = *futexaddr;					      \
@@ -60,12 +60,12 @@
 	if (cancel)							      \
 	  LIBC_CANCEL_RESET (oldtype);					      \
 									      \
-	if (status == -EINTR)						      \
+	if (status == EINTR)						      \
 	  result = EINTR;						      \
-	else if (status == -ETIMEDOUT)					      \
+	else if (status == ETIMEDOUT)					      \
 	  result = EAGAIN;						      \
 	else								      \
-	  assert (status == 0 || status == -EWOULDBLOCK);		      \
+	  assert (status == 0 || status == EAGAIN);			      \
 									      \
 	pthread_mutex_lock (&__aio_requests_mutex);			      \
       }									      \
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
index 74482b7a38..2b9ae4b571 100644
--- a/sysdeps/nptl/fork.c
+++ b/sysdeps/nptl/fork.c
@@ -30,6 +30,7 @@
 #include <nptl/pthreadP.h>
 #include <fork.h>
 #include <arch-fork.h>
+#include <futex-internal.h>
 
 
 static void
@@ -219,7 +220,7 @@ __libc_fork (void)
 
 	  if (atomic_decrement_and_test (&allp->handler->refcntr)
 	      && allp->handler->need_signal)
-	    lll_futex_wake (&allp->handler->refcntr, 1, LLL_PRIVATE);
+	    futex_wake (&allp->handler->refcntr, 1, FUTEX_PRIVATE);
 
 	  allp = allp->next;
 	}
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
new file mode 100644
index 0000000000..4f8c8fe72d
--- /dev/null
+++ b/sysdeps/nptl/futex-internal.h
@@ -0,0 +1,203 @@
+/* futex operations for glibc-internal use.  Stub version; do not include
+   this file directly.
+   Copyright (C) 2014-2015 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/>.  */
+
+#ifndef STUB_FUTEX_INTERNAL_H
+#define STUB_FUTEX_INTERNAL_H
+
+#include <sys/time.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <libc-internal.h>
+
+/* This file defines futex operations used internally in glibc.  A futex
+   consists of the so-called futex word in userspace, which is of type
+   unsigned int and represents an application-specific condition, and kernel
+   state associated with this particular futex word (e.g., wait queues).  The
+   futex operations we provide are wrappers for the futex syscalls and add
+   glibc-specific error checking of the syscall return value.  We abort on
+   error codes that are caused by bugs in glibc or in the calling application,
+   or when an error code is not known.  We return error codes that can arise
+   in correct executions to the caller.  Each operation calls out exactly the
+   return values that callers need to handle.
+
+   The private flag must be either FUTEX_PRIVATE or FUTEX_SHARED.
+   FUTEX_PRIVATE is always supported, and the implementation can internally
+   use FUTEX_SHARED when FUTEX_PRIVATE is requested.  FUTEX_SHARED is not
+   necessarily supported (use futex_supports_pshared to detect this).
+
+   We expect callers to only use these operations if futexes and the
+   specific futex operations being used are supported (e.g., FUTEX_SHARED).
+
+   Given that waking other threads waiting on a futex involves concurrent
+   accesses to the futex word, you must use atomic operations to access the
+   futex word.
+
+   Both absolute and relative timeouts can be used.  An absolute timeout
+   expires when the given specific point in time on the CLOCK_REALTIME clock
+   passes, or when it already has passed.  A relative timeout expires when
+   the given duration of time on the CLOCK_MONOTONIC clock passes.  Relative
+   timeouts may be imprecise (see futex_supports_exact_relative_timeouts).
+
+   Due to POSIX requirements on when synchronization data structures such
+   as mutexes or semaphores can be destroyed and due to the futex design
+   having separate fast/slow paths for wake-ups, we need to consider that
+   futex_wake calls might effectively target a data structure that has been
+   destroyed and reused for another object, or unmapped; thus, some
+   errors or spurious wake-ups can happen in correct executions that would
+   not be possible in a program using just a single futex whose lifetime
+   does not end before the program terminates.  For background, see:
+   https://sourceware.org/ml/libc-alpha/2014-04/msg00075.html
+   https://lkml.org/lkml/2014/11/27/472  */
+
+/* Defined this way for interoperability with lowlevellock.
+   FUTEX_PRIVATE must be zero because the initializers for pthread_mutex_t,
+   pthread_rwlock_t, and pthread_cond_t initialize the respective field of
+   those structures to zero, and we want FUTEX_PRIVATE to be the default.  */
+#define FUTEX_PRIVATE LLL_PRIVATE
+#define FUTEX_SHARED  LLL_SHARED
+#if FUTEX_PRIVATE != 0
+# error FUTEX_PRIVATE must be equal to 0
+#endif
+
+/* Returns EINVAL if PSHARED is neither PTHREAD_PROCESS_PRIVATE nor
+   PTHREAD_PROCESS_SHARED; otherwise, returns 0 if PSHARED is supported, and
+   ENOTSUP if not.  */
+static __always_inline int
+futex_supports_pshared (int pshared);
+
+/* Returns true if relative timeouts are robust to concurrent changes to the
+   system clock.  If this returns false, relative timeouts can still be used
+   but might be effectively longer or shorter than requested.  */
+static __always_inline bool
+futex_supports_exact_relative_timeouts (void);
+
+/* Atomically wrt other futex operations on the same futex, this blocks iff
+   the value *FUTEX_WORD matches the expected value.  This is
+   semantically equivalent to:
+     l = <get lock associated with futex> (FUTEX_WORD);
+     wait_flag = <get wait_flag associated with futex> (FUTEX_WORD);
+     lock (l);
+     val = atomic_load_relaxed (FUTEX_WORD);
+     if (val != expected) { unlock (l); return EAGAIN; }
+     atomic_store_relaxed (wait_flag, true);
+     unlock (l);
+     // Now block; can time out in futex_time_wait (see below)
+     while (atomic_load_relaxed(wait_flag) && !<spurious wake-up>);
+
+   Note that no guarantee of a happens-before relation between a woken
+   futex_wait and a futex_wake is documented; however, this does not matter
+   in practice because we have to consider spurious wake-ups (see below),
+   and thus would not be able to reliably reason about which futex_wake woke
+   us.
+
+   Returns 0 if woken by a futex operation or spuriously.  (Note that due to
+   the POSIX requirements mentioned above, we need to conservatively assume
+   that unrelated futex_wake operations could wake this futex; it is easiest
+   to just be prepared for spurious wake-ups.)
+   Returns EAGAIN if the futex word did not match the expected value.
+   Returns EINTR if waiting was interrupted by a signal.
+
+   Note that some previous code in glibc assumed the underlying futex
+   operation (e.g., syscall) to start with or include the equivalent of a
+   seq_cst fence; this allows one to avoid an explicit seq_cst fence before
+   a futex_wait call when synchronizing similar to Dekker synchronization.
+   However, we make no such guarantee here.  */
+static __always_inline int
+futex_wait (unsigned int *futex_word, unsigned int expected, int private);
+
+/* Like futex_wait but does not provide any indication why we stopped waiting.
+   Thus, when this function returns, you have to always check FUTEX_WORD to
+   determine whether you need to continue waiting, and you cannot detect
+   whether the waiting was interrupted by a signal.  Example use:
+     while (atomic_load_relaxed (&futex_word) == 23)
+       futex_wait_simple (&futex_word, 23, FUTEX_PRIVATE);
+   This is common enough to make providing this wrapper worthwhile.  */
+static __always_inline void
+futex_wait_simple (unsigned int *futex_word, unsigned int expected,
+		   int private)
+{
+  ignore_value (futex_wait (futex_word, expected, private));
+}
+
+
+/* Like futex_wait but is a POSIX cancellation point.  */
+static __always_inline int
+futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
+		       int private);
+
+/* Like futex_wait, but will eventually time out (i.e., stop being
+   blocked) after the duration of time provided (i.e., RELTIME) has
+   passed.  The caller must provide a normalized RELTIME.  RELTIME can also
+   equal NULL, in which case this function behaves equivalent to futex_wait.
+
+   Returns the same values as futex_wait under those same conditions;
+   additionally, returns ETIMEDOUT if the timeout expired.
+   */
+static __always_inline int
+futex_reltimed_wait (unsigned int* futex_word, unsigned int expected,
+		     const struct timespec* reltime, int private);
+
+/* Like futex_reltimed_wait but is a POSIX cancellation point.  */
+static __always_inline int
+futex_reltimed_wait_cancelable (unsigned int* futex_word,
+				unsigned int expected,
+			        const struct timespec* reltime, int private);
+
+/* Like futex_reltimed_wait, but the provided timeout (ABSTIME) is an
+   absolute point in time; a call will time out after this point in time.  */
+static __always_inline int
+futex_abstimed_wait (unsigned int* futex_word, unsigned int expected,
+		     const struct timespec* abstime, int private);
+
+/* Like futex_reltimed_wait but is a POSIX cancellation point.  */
+static __always_inline int
+futex_abstimed_wait_cancelable (unsigned int* futex_word,
+				unsigned int expected,
+			        const struct timespec* abstime, int private);
+
+/* Atomically wrt other futex operations on the same futex, this unblocks the
+   specified number of processes, or all processes blocked on this futex if
+   there are fewer than the specified number.  Semantically, this is
+   equivalent to:
+     l = <get lock associated with futex> (FUTEX_WORD);
+     lock (l);
+     for (res = 0; PROCESSES_TO_WAKE > 0; PROCESSES_TO_WAKE--, res++) {
+       if (<no process blocked on futex>) break;
+       wf = <get wait_flag of a process blocked on futex> (FUTEX_WORD);
+       // No happens-before guarantee with woken futex_wait (see above)
+       atomic_store_relaxed (wf, 0);
+     }
+     return res;
+
+   Note that we need to support futex_wake calls to past futexes whose memory
+   has potentially been reused due to POSIX' requirements on synchronization
+   object destruction (see above); therefore, we must not report or abort
+   on most errors.  */
+static __always_inline void
+futex_wake (unsigned int* futex_word, int processes_to_wake, int private);
+
+/* Calls __libc_fatal with an error message.  Convenience function for
+   concrete implementations of the futex interface.  */
+static __always_inline __attribute__ ((__noreturn__)) void
+futex_fatal_error (void)
+{
+  __libc_fatal ("The futex facility returned an unexpected error code.");
+}
+
+#endif  /* futex-internal.h */
diff --git a/sysdeps/nptl/gai_misc.h b/sysdeps/nptl/gai_misc.h
index a34dbc0dd9..96c8fa0f91 100644
--- a/sysdeps/nptl/gai_misc.h
+++ b/sysdeps/nptl/gai_misc.h
@@ -23,14 +23,14 @@
 #include <assert.h>
 #include <signal.h>
 #include <nptl/pthreadP.h>
-#include <lowlevellock.h>
+#include <futex-internal.h>
 
 #define DONT_NEED_GAI_MISC_COND	1
 
 #define GAI_MISC_NOTIFY(waitlist) \
   do {									      \
     if (*waitlist->counterp > 0 && --*waitlist->counterp == 0)		      \
-      lll_futex_wake (waitlist->counterp, 1, LLL_PRIVATE);		      \
+      futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE);     \
   } while (0)
 
 #define GAI_MISC_WAIT(result, futex, timeout, cancel) \
@@ -49,9 +49,9 @@
 	int status;							      \
 	do								      \
 	  {								      \
-	    status = lll_futex_timed_wait (futexaddr, oldval, timeout,	      \
-					   LLL_PRIVATE);		      \
-	    if (status != -EWOULDBLOCK)					      \
+	    status = futex_reltimed_wait ((unsigned int *) futexaddr, oldval, \
+					  timeout, FUTEX_PRIVATE);	      \
+	    if (status != EAGAIN)					      \
 	      break;							      \
 									      \
 	    oldval = *futexaddr;					      \
@@ -61,12 +61,12 @@
 	if (cancel)							      \
 	  LIBC_CANCEL_RESET (oldtype);					      \
 									      \
-	if (status == -EINTR)						      \
+	if (status == EINTR)						      \
 	  result = EINTR;						      \
-	else if (status == -ETIMEDOUT)					      \
+	else if (status == ETIMEDOUT)					      \
 	  result = EAGAIN;						      \
 	else								      \
-	  assert (status == 0 || status == -EWOULDBLOCK);		      \
+	  assert (status == 0 || status == EAGAIN);			      \
 									      \
 	pthread_mutex_lock (&__gai_requests_mutex);			      \
       }									      \
diff --git a/sysdeps/sparc/nptl/pthread_barrier_init.c b/sysdeps/sparc/nptl/pthread_barrier_init.c
index aa21a63f2d..86ec7d0348 100644
--- a/sysdeps/sparc/nptl/pthread_barrier_init.c
+++ b/sysdeps/sparc/nptl/pthread_barrier_init.c
@@ -35,10 +35,9 @@ __pthread_barrier_init (barrier, attr, count)
   struct pthread_barrierattr *iattr = (struct pthread_barrierattr *) attr;
   if (iattr != NULL)
     {
-      if (iattr->pshared != PTHREAD_PROCESS_PRIVATE
-	  && __builtin_expect (iattr->pshared != PTHREAD_PROCESS_SHARED, 0))
-	/* Invalid attribute.  */
-	return EINVAL;
+      int err = futex_supports_pshared (iattr->pshared);
+      if (err != 0)
+	return err;
     }
 
   ibarrier = (union sparc_pthread_barrier *) barrier;
diff --git a/sysdeps/sparc/nptl/pthread_barrier_wait.c b/sysdeps/sparc/nptl/pthread_barrier_wait.c
index dd4c336dc2..9e9806a31a 100644
--- a/sysdeps/sparc/nptl/pthread_barrier_wait.c
+++ b/sysdeps/sparc/nptl/pthread_barrier_wait.c
@@ -21,6 +21,7 @@
 #include <lowlevellock.h>
 #include <pthreadP.h>
 #include <sparc-nptl.h>
+#include <futex-internal.h>
 
 /* Wait on barrier.  */
 int
@@ -31,6 +32,7 @@ __pthread_barrier_wait (barrier)
     = (union sparc_pthread_barrier *) barrier;
   int result = 0;
   int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
+  int futex_private = ibarrier->s.pshared ? FUTEX_SHARED : FUTEX_PRIVATE;
 
   /* Make sure we are alone.  */
   lll_lock (ibarrier->b.lock, private);
@@ -46,7 +48,7 @@ __pthread_barrier_wait (barrier)
       ++ibarrier->b.curr_event;
 
       /* Wake up everybody.  */
-      lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
+      futex_wake (&ibarrier->b.curr_event, INT_MAX, futex_private);
 
       /* This is the thread which finished the serialization.  */
       result = PTHREAD_BARRIER_SERIAL_THREAD;
@@ -62,7 +64,7 @@ __pthread_barrier_wait (barrier)
 
       /* Wait for the event counter of the barrier to change.  */
       do
-	lll_futex_wait (&ibarrier->b.curr_event, event, private);
+	futex_wait_simple (&ibarrier->b.curr_event, event, futex_private);
       while (event == ibarrier->b.curr_event);
     }
 
diff --git a/sysdeps/sparc/sparc32/pthread_barrier_wait.c b/sysdeps/sparc/sparc32/pthread_barrier_wait.c
index 81d22b0653..5e1aa1159c 100644
--- a/sysdeps/sparc/sparc32/pthread_barrier_wait.c
+++ b/sysdeps/sparc/sparc32/pthread_barrier_wait.c
@@ -21,6 +21,7 @@
 #include <lowlevellock.h>
 #include <pthreadP.h>
 #include <sparc-nptl.h>
+#include <futex-internal.h>
 
 /* Wait on barrier.  */
 int
@@ -31,6 +32,7 @@ __pthread_barrier_wait (barrier)
     = (union sparc_pthread_barrier *) barrier;
   int result = 0;
   int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
+  int futex_private = ibarrier->s.pshared ? FUTEX_SHARED : FUTEX_PRIVATE;
 
   /* Make sure we are alone.  */
   lll_lock (ibarrier->b.lock, private);
@@ -46,7 +48,7 @@ __pthread_barrier_wait (barrier)
       ++ibarrier->b.curr_event;
 
       /* Wake up everybody.  */
-      lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
+      futex_wake (&ibarrier->b.curr_event, INT_MAX, futex_private);
 
       /* This is the thread which finished the serialization.  */
       result = PTHREAD_BARRIER_SERIAL_THREAD;
@@ -62,7 +64,7 @@ __pthread_barrier_wait (barrier)
 
       /* Wait for the event counter of the barrier to change.  */
       do
-	lll_futex_wait (&ibarrier->b.curr_event, event, private);
+	futex_wait_simple (&ibarrier->b.curr_event, event, futex_private);
       while (event == ibarrier->b.curr_event);
     }
 
diff --git a/sysdeps/sparc/sparc32/sem_init.c b/sysdeps/sparc/sparc32/sem_init.c
index 7c46cee900..1c7c455617 100644
--- a/sysdeps/sparc/sparc32/sem_init.c
+++ b/sysdeps/sparc/sparc32/sem_init.c
@@ -20,23 +20,7 @@
 #include <semaphore.h>
 #include <shlib-compat.h>
 #include "semaphoreP.h"
-#include <kernel-features.h>
-
-/* Returns FUTEX_PRIVATE if pshared is zero and private futexes are supported;
-   returns FUTEX_SHARED otherwise.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline int
-futex_private_if_supported (int pshared)
-{
-  if (pshared != 0)
-    return LLL_SHARED;
-#ifdef __ASSUME_PRIVATE_FUTEX
-  return LLL_PRIVATE;
-#else
-  return THREAD_GETMEM (THREAD_SELF, header.private_futex)
-      ^ FUTEX_PRIVATE_FLAG;
-#endif
-}
+#include <futex-internal.h>
 
 
 int
@@ -49,6 +33,14 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
       return -1;
     }
 
+  pshared = pshared != 0 ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
+  int err = futex_supports_pshared (pshared);
+  if (err != 0)
+    {
+      __set_errno (err);
+      return -1;
+    }
+
   /* Map to the internal type.  */
   struct new_sem *isem = (struct new_sem *) sem;
 
@@ -57,7 +49,8 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
   isem->pad = 0;
   isem->nwaiters = 0;
 
-  isem->private = futex_private_if_supported (pshared);
+  isem->private = (pshared == PTHREAD_PROCESS_PRIVATE
+		   ? FUTEX_PRIVATE : FUTEX_SHARED);
 
   return 0;
 }
diff --git a/sysdeps/sparc/sparc32/sem_open.c b/sysdeps/sparc/sparc32/sem_open.c
index 2698d195ba..16cb9ad591 100644
--- a/sysdeps/sparc/sparc32/sem_open.c
+++ b/sysdeps/sparc/sparc32/sem_open.c
@@ -199,7 +199,7 @@ sem_open (const char *name, int oflag, ...)
       sem.newsem.nwaiters = 0;
 
       /* This always is a shared semaphore.  */
-      sem.newsem.private = LLL_SHARED;
+      sem.newsem.private = FUTEX_SHARED;
 
       /* Initialize the remaining bytes as well.  */
       memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',
diff --git a/sysdeps/sparc/sparc32/sem_post.c b/sysdeps/sparc/sparc32/sem_post.c
index c9f85a06f5..fd1a2fe910 100644
--- a/sysdeps/sparc/sparc32/sem_post.c
+++ b/sysdeps/sparc/sparc32/sem_post.c
@@ -23,34 +23,10 @@
 #include <lowlevellock.h>
 #include <internaltypes.h>
 #include <semaphore.h>
+#include <futex-internal.h>
 
 #include <shlib-compat.h>
 
-/* Wrapper for lll_futex_wake, with error checking.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline void
-futex_wake (unsigned int* futex, int processes_to_wake, int private)
-{
-  int res = lll_futex_wake (futex, processes_to_wake, private);
-  /* No error.  Ignore the number of woken processes.  */
-  if (res >= 0)
-    return;
-  switch (res)
-    {
-    case -EFAULT: /* Could have happened due to memory reuse.  */
-    case -EINVAL: /* Could be either due to incorrect alignment (a bug in
-		     glibc or in the application) or due to memory being
-		     reused for a PI futex.  We cannot distinguish between the
-		     two causes, and one of them is correct use, so we do not
-		     act in this case.  */
-      return;
-    case -ENOSYS: /* Must have been caused by a glibc bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      abort ();
-    }
-}
-
 
 /* See sem_wait for an explanation of the algorithm.  */
 int
diff --git a/sysdeps/sparc/sparc32/sem_wait.c b/sysdeps/sparc/sparc32/sem_wait.c
index c1fd10c9d0..fce7ed43ee 100644
--- a/sysdeps/sparc/sparc32/sem_wait.c
+++ b/sysdeps/sparc/sparc32/sem_wait.c
@@ -17,6 +17,7 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <lowlevellock.h>	/* lll_futex* used by the old code.  */
 #include "sem_waitcommon.c"
 
 int
diff --git a/sysdeps/sparc/sparc32/sem_waitcommon.c b/sysdeps/sparc/sparc32/sem_waitcommon.c
index 9c1c6a5af7..9e43d45431 100644
--- a/sysdeps/sparc/sparc32/sem_waitcommon.c
+++ b/sysdeps/sparc/sparc32/sem_waitcommon.c
@@ -19,7 +19,7 @@
 
 #include <errno.h>
 #include <sysdep.h>
-#include <lowlevellock.h>
+#include <futex-internal.h>
 #include <internaltypes.h>
 #include <semaphore.h>
 #include <sys/time.h>
@@ -28,104 +28,6 @@
 #include <shlib-compat.h>
 #include <atomic.h>
 
-/* Wrapper for lll_futex_wait with absolute timeout and error checking.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline int
-futex_abstimed_wait (unsigned int* futex, unsigned int expected,
-		     const struct timespec* abstime, int private, bool cancel)
-{
-  int err, oldtype;
-  if (abstime == NULL)
-    {
-      if (cancel)
-	oldtype = __pthread_enable_asynccancel ();
-      err = lll_futex_wait (futex, expected, private);
-      if (cancel)
-	__pthread_disable_asynccancel (oldtype);
-    }
-  else
-    {
-      struct timeval tv;
-      struct timespec rt;
-      int sec, nsec;
-
-      /* Get the current time.  */
-      __gettimeofday (&tv, NULL);
-
-      /* Compute relative timeout.  */
-      sec = abstime->tv_sec - tv.tv_sec;
-      nsec = abstime->tv_nsec - tv.tv_usec * 1000;
-      if (nsec < 0)
-        {
-          nsec += 1000000000;
-          --sec;
-        }
-
-      /* Already timed out?  */
-      if (sec < 0)
-        return ETIMEDOUT;
-
-      /* Do wait.  */
-      rt.tv_sec = sec;
-      rt.tv_nsec = nsec;
-      if (cancel)
-	oldtype = __pthread_enable_asynccancel ();
-      err = lll_futex_timed_wait (futex, expected, &rt, private);
-      if (cancel)
-	__pthread_disable_asynccancel (oldtype);
-    }
-  switch (err)
-    {
-    case 0:
-    case -EAGAIN:
-    case -EINTR:
-    case -ETIMEDOUT:
-      return -err;
-
-    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
-    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
-		     being normalized.  Must have been caused by a glibc or
-		     application bug.  */
-    case -ENOSYS: /* Must have been caused by a glibc bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      abort ();
-    }
-}
-
-/* Wrapper for lll_futex_wake, with error checking.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline void
-futex_wake (unsigned int* futex, int processes_to_wake, int private)
-{
-  int res = lll_futex_wake (futex, processes_to_wake, private);
-  /* No error.  Ignore the number of woken processes.  */
-  if (res >= 0)
-    return;
-  switch (res)
-    {
-    case -EFAULT: /* Could have happened due to memory reuse.  */
-    case -EINVAL: /* Could be either due to incorrect alignment (a bug in
-		     glibc or in the application) or due to memory being
-		     reused for a PI futex.  We cannot distinguish between the
-		     two causes, and one of them is correct use, so we do not
-		     act in this case.  */
-      return;
-    case -ENOSYS: /* Must have been caused by a glibc bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      abort ();
-    }
-}
-
-
-/* Set this to true if you assume that, in contrast to current Linux futex
-   documentation, lll_futex_wake can return -EINTR only if interrupted by a
-   signal, not spuriously due to some other reason.
-   TODO Discuss EINTR conditions with the Linux kernel community.  For
-   now, we set this to true to not change behavior of semaphores compared
-   to previous glibc builds.  */
-static const int sem_assume_only_signals_cause_futex_EINTR = 1;
 
 static void
 __sem_wait_32_finish (struct new_sem *sem);
@@ -149,8 +51,8 @@ do_futex_wait (struct new_sem *sem, const struct timespec *abstime)
 {
   int err;
 
-  err = futex_abstimed_wait (&sem->value, SEM_NWAITERS_MASK, abstime,
-			     sem->private, true);
+  err = futex_abstimed_wait_cancelable (&sem->value, SEM_NWAITERS_MASK,
+					abstime, sem->private);
 
   return err;
 }
@@ -202,8 +104,7 @@ __new_sem_wait_slow (struct new_sem *sem, const struct timespec *abstime)
 	  __sparc32_atomic_do_unlock24(&sem->pad);
 
 	  err = do_futex_wait(sem, abstime);
-	  if (err == ETIMEDOUT ||
-	      (err == EINTR && sem_assume_only_signals_cause_futex_EINTR))
+	  if (err == ETIMEDOUT || err == EINTR)
 	    {
 	      __set_errno (err);
 	      err = -1;
diff --git a/sysdeps/unix/sysv/linux/futex-internal.h b/sysdeps/unix/sysv/linux/futex-internal.h
new file mode 100644
index 0000000000..aca0911252
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/futex-internal.h
@@ -0,0 +1,251 @@
+/* futex operations for glibc-internal use.  Linux version.
+   Copyright (C) 2014-2015 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/>.  */
+
+#ifndef FUTEX_INTERNAL_H
+#define FUTEX_INTERNAL_H
+
+#include <sysdeps/nptl/futex-internal.h>
+#include <errno.h>
+#include <lowlevellock-futex.h>
+#include <nptl/pthreadP.h>
+
+/* See sysdeps/nptl/futex-internal.h for documentation; this file only
+   contains Linux-specific comments.
+
+   The Linux kernel treats provides absolute timeouts based on the
+   CLOCK_REALTIME clock and relative timeouts measured against the
+   CLOCK_MONOTONIC clock.
+
+   We expect a Linux kernel version of 2.6.22 or more recent (since this
+   version, EINTR is not returned on spurious wake-ups anymore).  */
+
+/* FUTEX_SHARED is always supported by the Linux kernel.  */
+static __always_inline int
+futex_supports_pshared (int pshared)
+{
+  if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
+    return 0;
+  else if (pshared == PTHREAD_PROCESS_SHARED)
+    return 0;
+  else
+    return EINVAL;
+}
+
+/* The Linux kernel supports relative timeouts measured against the
+   CLOCK_MONOTONIC clock.  */
+static __always_inline bool
+futex_supports_exact_relative_timeouts (void)
+{
+  return true;
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_wait (unsigned int *futex_word, unsigned int expected, int private)
+{
+  int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+      return -err;
+
+    case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
+		       int private)
+{
+  int oldtype;
+  oldtype = __pthread_enable_asynccancel ();
+  int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+      return -err;
+
+    case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
+		     const struct timespec *reltime, int private)
+{
+  int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_reltimed_wait_cancelable (unsigned int *futex_word,
+				unsigned int expected,
+			        const struct timespec *reltime, int private)
+{
+  int oldtype;
+  oldtype = __pthread_enable_asynccancel ();
+  int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
+		     const struct timespec *abstime, int private)
+{
+  /* Work around the fact that the kernel rejects negative timeout values
+     despite them being valid.  */
+  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
+    return ETIMEDOUT;
+  int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,
+					 FUTEX_CLOCK_REALTIME, private);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline int
+futex_abstimed_wait_cancelable (unsigned int *futex_word,
+				unsigned int expected,
+			        const struct timespec *abstime, int private)
+{
+  /* Work around the fact that the kernel rejects negative timeout values
+     despite them being valid.  */
+  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
+    return ETIMEDOUT;
+  int oldtype;
+  oldtype = __pthread_enable_asynccancel ();
+  int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,
+					 FUTEX_CLOCK_REALTIME, private);
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+/* See sysdeps/nptl/futex-internal.h for details.  */
+static __always_inline void
+futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
+{
+  int res = lll_futex_wake (futex_word, processes_to_wake, private);
+  /* No error.  Ignore the number of woken processes.  */
+  if (res >= 0)
+    return;
+  switch (res)
+    {
+    case -EFAULT: /* Could have happened due to memory reuse.  */
+    case -EINVAL: /* Could be either due to incorrect alignment (a bug in
+		     glibc or in the application) or due to memory being
+		     reused for a PI futex.  We cannot distinguish between the
+		     two causes, and one of them is correct use, so we do not
+		     act in this case.  */
+      return;
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
+#endif  /* futex-internal.h */