rt: Move generic implementation from sysdeps/pthread to rt

The pthread-based implementation is the generic one.  Replacing
the stubs makes it clear that they do not have to be adjusted for
the libpthread move.

Result of:

    git mv -f sysdeps/pthread/aio_misc.h sysdeps/generic/
    git mv sysdeps/pthread/timer_routines.c sysdeps/htl/
    git mv -f sysdeps/pthread/{aio,lio,timer}_*.c rt/

Followed by manual adjustment of the #include paths in
sysdeps/unix/sysv/linux/wordsize-64, and a move of the version
definitions formerly in sysdeps/pthread/Versions.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

18 files changed, 1931 insertions, 120 deletions

diff --git a/rt/Versions b/rt/Versions
index 309486b..26c6d1a 100644
--- a/rt/Versions
+++ b/rt/Versions
@@ -47,6 +47,10 @@ librt {
     mq_timedsend;
     mq_unlink;
   }
+  GLIBC_2.4 {
+    lio_listio;
+    lio_listio64;
+  }
   GLIBC_2.7 {
    __mq_open_2;
   }
diff --git a/rt/aio_cancel.c b/rt/aio_cancel.c
index dba1e45..63fd88f 100644
--- a/rt/aio_cancel.c
+++ b/rt/aio_cancel.c
@@ -1,6 +1,7 @@
-/* Cancel requests associated with given file descriptor.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Cancel requests associated with given file descriptor.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -22,21 +23,135 @@
    we want to avoid code duplication by using aliases.  But gcc sees
    the different parameter lists and prints a warning.  We define here
    a function so that aio_cancel64 has no prototype.  */
+#ifndef aio_cancel
 #define aio_cancel64 XXX
 #include <aio.h>
 /* And undo the hack.  */
 #undef aio_cancel64
+#endif
 
+#include <assert.h>
 #include <errno.h>
+#include <fcntl.h>
+
+#include <aio_misc.h>
+
 
 int
 aio_cancel (int fildes, struct aiocb *aiocbp)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  struct requestlist *req = NULL;
+  int result = AIO_ALLDONE;
+
+  /* If fildes is invalid, error. */
+  if (fcntl (fildes, F_GETFL) < 0)
+    {
+      __set_errno (EBADF);
+      return -1;
+    }
+
+  /* Request the mutex.  */
+  pthread_mutex_lock (&__aio_requests_mutex);
+
+  /* We are asked to cancel a specific AIO request.  */
+  if (aiocbp != NULL)
+    {
+      /* If the AIO request is not for this descriptor it has no value
+	 to look for the request block.  */
+      if (aiocbp->aio_fildes != fildes)
+	{
+	  pthread_mutex_unlock (&__aio_requests_mutex);
+	  __set_errno (EINVAL);
+	  return -1;
+	}
+      else if (aiocbp->__error_code == EINPROGRESS)
+	{
+	  struct requestlist *last = NULL;
+
+	  req = __aio_find_req_fd (fildes);
+
+	  if (req == NULL)
+	    {
+	    not_found:
+	      pthread_mutex_unlock (&__aio_requests_mutex);
+	      __set_errno (EINVAL);
+	      return -1;
+	    }
+
+	  while (req->aiocbp != (aiocb_union *) aiocbp)
+	    {
+	      last = req;
+	      req = req->next_prio;
+	      if (req == NULL)
+		goto not_found;
+	    }
+
+	  /* Don't remove the entry if a thread is already working on it.  */
+	  if (req->running == allocated)
+	    {
+	      result = AIO_NOTCANCELED;
+	      req = NULL;
+	    }
+	  else
+	    {
+	      /* We can remove the entry.  */
+	      __aio_remove_request (last, req, 0);
+
+	      result = AIO_CANCELED;
+
+	      req->next_prio = NULL;
+	    }
+	}
+    }
+  else
+    {
+      /* Find the beginning of the list of all requests for this
+	 desriptor.  */
+      req = __aio_find_req_fd (fildes);
+
+      /* If any request is worked on by a thread it must be the first.
+	 So either we can delete all requests or all but the first.  */
+      if (req != NULL)
+	{
+	  if (req->running == allocated)
+	    {
+	      struct requestlist *old = req;
+	      req = req->next_prio;
+	      old->next_prio = NULL;
+
+	      result = AIO_NOTCANCELED;
+
+	      if (req != NULL)
+		__aio_remove_request (old, req, 1);
+	    }
+	  else
+	    {
+	      result = AIO_CANCELED;
+
+	      /* We can remove the entry.  */
+	      __aio_remove_request (NULL, req, 1);
+	    }
+	}
+    }
+
+  /* Mark requests as canceled and send signal.  */
+  while (req != NULL)
+    {
+      struct requestlist *old = req;
+      assert (req->running == yes || req->running == queued);
+      req->aiocbp->aiocb.__error_code = ECANCELED;
+      req->aiocbp->aiocb.__return_value = -1;
+      __aio_notify (req);
+      req = req->next_prio;
+      __aio_free_request (old);
+    }
+
+  /* Release the mutex.  */
+  pthread_mutex_unlock (&__aio_requests_mutex);
+
+  return result;
 }
 
+#ifndef aio_cancel
 weak_alias (aio_cancel, aio_cancel64)
-
-stub_warning (aio_cancel)
-stub_warning (aio_cancel64)
+#endif
diff --git a/rt/aio_error.c b/rt/aio_error.c
index 730b64b..ed664ae 100644
--- a/rt/aio_error.c
+++ b/rt/aio_error.c
@@ -28,11 +28,21 @@
 /* And undo the hack.  */
 #undef aio_error64
 
+#include <aio_misc.h>
+
 
 int
 aio_error (const struct aiocb *aiocbp)
 {
-  return aiocbp->__error_code;
+  int ret;
+
+  /* Acquire the mutex to make sure all operations for this request are
+     complete.  */
+  pthread_mutex_lock(&__aio_requests_mutex);
+  ret = aiocbp->__error_code;
+  pthread_mutex_unlock(&__aio_requests_mutex);
+
+  return ret;
 }
 
 weak_alias (aio_error, aio_error64)
diff --git a/rt/aio_fsync.c b/rt/aio_fsync.c
index 8672724..5a52e2f 100644
--- a/rt/aio_fsync.c
+++ b/rt/aio_fsync.c
@@ -1,6 +1,7 @@
-/* Synchronize I/O in given file descriptor.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Synchronize I/O in given file descriptor.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -26,24 +27,31 @@
 #include <aio.h>
 /* And undo the hack.  */
 #undef aio_fsync64
-
 #include <errno.h>
 #include <fcntl.h>
 
+#include <aio_misc.h>
+
+
 int
 aio_fsync (int op, struct aiocb *aiocbp)
 {
-  if (op != O_SYNC && op != O_DSYNC)
+  if (op != O_DSYNC && __builtin_expect (op != O_SYNC, 0))
     {
       __set_errno (EINVAL);
       return -1;
     }
 
-  __set_errno (ENOSYS);
-  return -1;
+  /* Verify that this is an open file descriptor.  */
+  if (__glibc_unlikely (fcntl (aiocbp->aio_fildes, F_GETFL) == -1))
+    {
+      __set_errno (EBADF);
+      return -1;
+    }
+
+  return (__aio_enqueue_request ((aiocb_union *) aiocbp,
+				 op == O_SYNC ? LIO_SYNC : LIO_DSYNC) == NULL
+	  ? -1 : 0);
 }
 
 weak_alias (aio_fsync, aio_fsync64)
-
-stub_warning (aio_fsync)
-stub_warning (aio_fsync64)
diff --git a/rt/aio_misc.c b/rt/aio_misc.c
index 2332f3e..b95f07d 100644
--- a/rt/aio_misc.c
+++ b/rt/aio_misc.c
@@ -1,6 +1,7 @@
-/* Handle general operations.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Handle general operations.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -17,12 +18,704 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <aio.h>
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/time.h>
 #include <aio_misc.h>
 
-/* This file is for internal code needed by the aio_* implementation.  */
+#ifndef aio_create_helper_thread
+# define aio_create_helper_thread __aio_create_helper_thread
 
+extern inline int
+__aio_create_helper_thread (pthread_t *threadp, void *(*tf) (void *), void *arg)
+{
+  pthread_attr_t attr;
+
+  /* Make sure the thread is created detached.  */
+  pthread_attr_init (&attr);
+  pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
+
+  int ret = pthread_create (threadp, &attr, tf, arg);
+
+  (void) pthread_attr_destroy (&attr);
+  return ret;
+}
+#endif
+
+static void add_request_to_runlist (struct requestlist *newrequest);
+
+/* Pool of request list entries.  */
+static struct requestlist **pool;
+
+/* Number of total and allocated pool entries.  */
+static size_t pool_max_size;
+static size_t pool_size;
+
+/* We implement a two dimensional array but allocate each row separately.
+   The macro below determines how many entries should be used per row.
+   It should better be a power of two.  */
+#define ENTRIES_PER_ROW	32
+
+/* How many rows we allocate at once.  */
+#define ROWS_STEP	8
+
+/* List of available entries.  */
+static struct requestlist *freelist;
+
+/* List of request waiting to be processed.  */
+static struct requestlist *runlist;
+
+/* Structure list of all currently processed requests.  */
+static struct requestlist *requests;
+
+/* Number of threads currently running.  */
+static int nthreads;
+
+/* Number of threads waiting for work to arrive. */
+static int idle_thread_count;
+
+
+/* These are the values used to optimize the use of AIO.  The user can
+   overwrite them by using the `aio_init' function.  */
+static struct aioinit optim =
+{
+  20,	/* int aio_threads;	Maximal number of threads.  */
+  64,	/* int aio_num;		Number of expected simultaneous requests. */
+  0,
+  0,
+  0,
+  0,
+  1,
+  0
+};
+
+
+/* Since the list is global we need a mutex protecting it.  */
+pthread_mutex_t __aio_requests_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+
+/* When you add a request to the list and there are idle threads present,
+   you signal this condition variable. When a thread finishes work, it waits
+   on this condition variable for a time before it actually exits. */
+pthread_cond_t __aio_new_request_notification = PTHREAD_COND_INITIALIZER;
+
+
+/* Functions to handle request list pool.  */
+static struct requestlist *
+get_elem (void)
+{
+  struct requestlist *result;
+
+  if (freelist == NULL)
+    {
+      struct requestlist *new_row;
+      int cnt;
+
+      assert (sizeof (struct aiocb) == sizeof (struct aiocb64));
+
+      if (pool_size + 1 >= pool_max_size)
+	{
+	  size_t new_max_size = pool_max_size + ROWS_STEP;
+	  struct requestlist **new_tab;
+
+	  new_tab = (struct requestlist **)
+	    realloc (pool, new_max_size * sizeof (struct requestlist *));
+
+	  if (new_tab == NULL)
+	    return NULL;
+
+	  pool_max_size = new_max_size;
+	  pool = new_tab;
+	}
+
+      /* Allocate the new row.  */
+      cnt = pool_size == 0 ? optim.aio_num : ENTRIES_PER_ROW;
+      new_row = (struct requestlist *) calloc (cnt,
+					       sizeof (struct requestlist));
+      if (new_row == NULL)
+	return NULL;
+
+      pool[pool_size++] = new_row;
+
+      /* Put all the new entries in the freelist.  */
+      do
+	{
+	  new_row->next_prio = freelist;
+	  freelist = new_row++;
+	}
+      while (--cnt > 0);
+    }
+
+  result = freelist;
+  freelist = freelist->next_prio;
+
+  return result;
+}
+
+
+void
+__aio_free_request (struct requestlist *elem)
+{
+  elem->running = no;
+  elem->next_prio = freelist;
+  freelist = elem;
+}
+
+
+struct requestlist *
+__aio_find_req (aiocb_union *elem)
+{
+  struct requestlist *runp = requests;
+  int fildes = elem->aiocb.aio_fildes;
+
+  while (runp != NULL && runp->aiocbp->aiocb.aio_fildes < fildes)
+    runp = runp->next_fd;
+
+  if (runp != NULL)
+    {
+      if (runp->aiocbp->aiocb.aio_fildes != fildes)
+	runp = NULL;
+      else
+	while (runp != NULL && runp->aiocbp != elem)
+	  runp = runp->next_prio;
+    }
+
+  return runp;
+}
+
+
+struct requestlist *
+__aio_find_req_fd (int fildes)
+{
+  struct requestlist *runp = requests;
+
+  while (runp != NULL && runp->aiocbp->aiocb.aio_fildes < fildes)
+    runp = runp->next_fd;
+
+  return (runp != NULL && runp->aiocbp->aiocb.aio_fildes == fildes
+	  ? runp : NULL);
+}
+
+
+void
+__aio_remove_request (struct requestlist *last, struct requestlist *req,
+		      int all)
+{
+  assert (req->running == yes || req->running == queued
+	  || req->running == done);
+
+  if (last != NULL)
+    last->next_prio = all ? NULL : req->next_prio;
+  else
+    {
+      if (all || req->next_prio == NULL)
+	{
+	  if (req->last_fd != NULL)
+	    req->last_fd->next_fd = req->next_fd;
+	  else
+	    requests = req->next_fd;
+	  if (req->next_fd != NULL)
+	    req->next_fd->last_fd = req->last_fd;
+	}
+      else
+	{
+	  if (req->last_fd != NULL)
+	    req->last_fd->next_fd = req->next_prio;
+	  else
+	    requests = req->next_prio;
+
+	  if (req->next_fd != NULL)
+	    req->next_fd->last_fd = req->next_prio;
+
+	  req->next_prio->last_fd = req->last_fd;
+	  req->next_prio->next_fd = req->next_fd;
+
+	  /* Mark this entry as runnable.  */
+	  req->next_prio->running = yes;
+	}
+
+      if (req->running == yes)
+	{
+	  struct requestlist *runp = runlist;
+
+	  last = NULL;
+	  while (runp != NULL)
+	    {
+	      if (runp == req)
+		{
+		  if (last == NULL)
+		    runlist = runp->next_run;
+		  else
+		    last->next_run = runp->next_run;
+		  break;
+		}
+	      last = runp;
+	      runp = runp->next_run;
+	    }
+	}
+    }
+}
+
+
+/* The thread handler.  */
+static void *handle_fildes_io (void *arg);
+
+
+/* User optimization.  */
 void
 __aio_init (const struct aioinit *init)
 {
+  /* Get the mutex.  */
+  pthread_mutex_lock (&__aio_requests_mutex);
+
+  /* Only allow writing new values if the table is not yet allocated.  */
+  if (pool == NULL)
+    {
+      optim.aio_threads = init->aio_threads < 1 ? 1 : init->aio_threads;
+      assert (powerof2 (ENTRIES_PER_ROW));
+      optim.aio_num = (init->aio_num < ENTRIES_PER_ROW
+		       ? ENTRIES_PER_ROW
+		       : init->aio_num & ~(ENTRIES_PER_ROW - 1));
+    }
+
+  if (init->aio_idle_time != 0)
+    optim.aio_idle_time = init->aio_idle_time;
+
+  /* Release the mutex.  */
+  pthread_mutex_unlock (&__aio_requests_mutex);
 }
 weak_alias (__aio_init, aio_init)
+
+
+/* The main function of the async I/O handling.  It enqueues requests
+   and if necessary starts and handles threads.  */
+struct requestlist *
+__aio_enqueue_request (aiocb_union *aiocbp, int operation)
+{
+  int result = 0;
+  int policy, prio;
+  struct sched_param param;
+  struct requestlist *last, *runp, *newp;
+  int running = no;
+
+  if (operation == LIO_SYNC || operation == LIO_DSYNC)
+    aiocbp->aiocb.aio_reqprio = 0;
+  else if (aiocbp->aiocb.aio_reqprio < 0
+#ifdef AIO_PRIO_DELTA_MAX
+	   || aiocbp->aiocb.aio_reqprio > AIO_PRIO_DELTA_MAX
+#endif
+	   )
+    {
+      /* Invalid priority value.  */
+      __set_errno (EINVAL);
+      aiocbp->aiocb.__error_code = EINVAL;
+      aiocbp->aiocb.__return_value = -1;
+      return NULL;
+    }
+
+  /* Compute priority for this request.  */
+  pthread_getschedparam (pthread_self (), &policy, &param);
+  prio = param.sched_priority - aiocbp->aiocb.aio_reqprio;
+
+  /* Get the mutex.  */
+  pthread_mutex_lock (&__aio_requests_mutex);
+
+  last = NULL;
+  runp = requests;
+  /* First look whether the current file descriptor is currently
+     worked with.  */
+  while (runp != NULL
+	 && runp->aiocbp->aiocb.aio_fildes < aiocbp->aiocb.aio_fildes)
+    {
+      last = runp;
+      runp = runp->next_fd;
+    }
+
+  /* Get a new element for the waiting list.  */
+  newp = get_elem ();
+  if (newp == NULL)
+    {
+      pthread_mutex_unlock (&__aio_requests_mutex);
+      __set_errno (EAGAIN);
+      return NULL;
+    }
+  newp->aiocbp = aiocbp;
+  newp->waiting = NULL;
+
+  aiocbp->aiocb.__abs_prio = prio;
+  aiocbp->aiocb.__policy = policy;
+  aiocbp->aiocb.aio_lio_opcode = operation;
+  aiocbp->aiocb.__error_code = EINPROGRESS;
+  aiocbp->aiocb.__return_value = 0;
+
+  if (runp != NULL
+      && runp->aiocbp->aiocb.aio_fildes == aiocbp->aiocb.aio_fildes)
+    {
+      /* The current file descriptor is worked on.  It makes no sense
+	 to start another thread since this new thread would fight
+	 with the running thread for the resources.  But we also cannot
+	 say that the thread processing this desriptor shall immediately
+	 after finishing the current job process this request if there
+	 are other threads in the running queue which have a higher
+	 priority.  */
+
+      /* Simply enqueue it after the running one according to the
+	 priority.  */
+      last = NULL;
+      while (runp->next_prio != NULL
+	     && runp->next_prio->aiocbp->aiocb.__abs_prio >= prio)
+	{
+	  last = runp;
+	  runp = runp->next_prio;
+	}
+
+      newp->next_prio = runp->next_prio;
+      runp->next_prio = newp;
+
+      running = queued;
+    }
+  else
+    {
+      running = yes;
+      /* Enqueue this request for a new descriptor.  */
+      if (last == NULL)
+	{
+	  newp->last_fd = NULL;
+	  newp->next_fd = requests;
+	  if (requests != NULL)
+	    requests->last_fd = newp;
+	  requests = newp;
+	}
+      else
+	{
+	  newp->next_fd = last->next_fd;
+	  newp->last_fd = last;
+	  last->next_fd = newp;
+	  if (newp->next_fd != NULL)
+	    newp->next_fd->last_fd = newp;
+	}
+
+      newp->next_prio = NULL;
+      last = NULL;
+    }
+
+  if (running == yes)
+    {
+      /* We try to create a new thread for this file descriptor.  The
+	 function which gets called will handle all available requests
+	 for this descriptor and when all are processed it will
+	 terminate.
+
+	 If no new thread can be created or if the specified limit of
+	 threads for AIO is reached we queue the request.  */
+
+      /* See if we need to and are able to create a thread.  */
+      if (nthreads < optim.aio_threads && idle_thread_count == 0)
+	{
+	  pthread_t thid;
+
+	  running = newp->running = allocated;
+
+	  /* Now try to start a thread.  */
+	  result = aio_create_helper_thread (&thid, handle_fildes_io, newp);
+	  if (result == 0)
+	    /* We managed to enqueue the request.  All errors which can
+	       happen now can be recognized by calls to `aio_return' and
+	       `aio_error'.  */
+	    ++nthreads;
+	  else
+	    {
+	      /* Reset the running flag.  The new request is not running.  */
+	      running = newp->running = yes;
+
+	      if (nthreads == 0)
+		{
+		  /* We cannot create a thread in the moment and there is
+		     also no thread running.  This is a problem.  `errno' is
+		     set to EAGAIN if this is only a temporary problem.  */
+		  __aio_remove_request (last, newp, 0);
+		}
+	      else
+		result = 0;
+	    }
+	}
+    }
+
+  /* Enqueue the request in the run queue if it is not yet running.  */
+  if (running == yes && result == 0)
+    {
+      add_request_to_runlist (newp);
+
+      /* If there is a thread waiting for work, then let it know that we
+	 have just given it something to do. */
+      if (idle_thread_count > 0)
+	pthread_cond_signal (&__aio_new_request_notification);
+    }
+
+  if (result == 0)
+    newp->running = running;
+  else
+    {
+      /* Something went wrong.  */
+      __aio_free_request (newp);
+      aiocbp->aiocb.__error_code = result;
+      __set_errno (result);
+      newp = NULL;
+    }
+
+  /* Release the mutex.  */
+  pthread_mutex_unlock (&__aio_requests_mutex);
+
+  return newp;
+}
+
+
+static void *
+handle_fildes_io (void *arg)
+{
+  pthread_t self = pthread_self ();
+  struct sched_param param;
+  struct requestlist *runp = (struct requestlist *) arg;
+  aiocb_union *aiocbp;
+  int policy;
+  int fildes;
+
+  pthread_getschedparam (self, &policy, &param);
+
+  do
+    {
+      /* If runp is NULL, then we were created to service the work queue
+	 in general, not to handle any particular request. In that case we
+	 skip the "do work" stuff on the first pass, and go directly to the
+	 "get work off the work queue" part of this loop, which is near the
+	 end. */
+      if (runp == NULL)
+	pthread_mutex_lock (&__aio_requests_mutex);
+      else
+	{
+	  /* Hopefully this request is marked as running.  */
+	  assert (runp->running == allocated);
+
+	  /* Update our variables.  */
+	  aiocbp = runp->aiocbp;
+	  fildes = aiocbp->aiocb.aio_fildes;
+
+	  /* Change the priority to the requested value (if necessary).  */
+	  if (aiocbp->aiocb.__abs_prio != param.sched_priority
+	      || aiocbp->aiocb.__policy != policy)
+	    {
+	      param.sched_priority = aiocbp->aiocb.__abs_prio;
+	      policy = aiocbp->aiocb.__policy;
+	      pthread_setschedparam (self, policy, &param);
+	    }
+
+	  /* Process request pointed to by RUNP.  We must not be disturbed
+	     by signals.  */
+	  if ((aiocbp->aiocb.aio_lio_opcode & 127) == LIO_READ)
+	    {
+	      if (sizeof (off_t) != sizeof (off64_t)
+		  && aiocbp->aiocb.aio_lio_opcode & 128)
+		aiocbp->aiocb.__return_value =
+		  TEMP_FAILURE_RETRY (__pread64 (fildes, (void *)
+						 aiocbp->aiocb64.aio_buf,
+						 aiocbp->aiocb64.aio_nbytes,
+						 aiocbp->aiocb64.aio_offset));
+	      else
+		aiocbp->aiocb.__return_value =
+		  TEMP_FAILURE_RETRY (__libc_pread (fildes,
+						    (void *)
+						    aiocbp->aiocb.aio_buf,
+						    aiocbp->aiocb.aio_nbytes,
+						    aiocbp->aiocb.aio_offset));
+
+	      if (aiocbp->aiocb.__return_value == -1 && errno == ESPIPE)
+		/* The Linux kernel is different from others.  It returns
+		   ESPIPE if using pread on a socket.  Other platforms
+		   simply ignore the offset parameter and behave like
+		   read.  */
+		aiocbp->aiocb.__return_value =
+		  TEMP_FAILURE_RETRY (read (fildes,
+					    (void *) aiocbp->aiocb64.aio_buf,
+					    aiocbp->aiocb64.aio_nbytes));
+	    }
+	  else if ((aiocbp->aiocb.aio_lio_opcode & 127) == LIO_WRITE)
+	    {
+	      if (sizeof (off_t) != sizeof (off64_t)
+		  && aiocbp->aiocb.aio_lio_opcode & 128)
+		aiocbp->aiocb.__return_value =
+		  TEMP_FAILURE_RETRY (__pwrite64 (fildes, (const void *)
+						  aiocbp->aiocb64.aio_buf,
+						  aiocbp->aiocb64.aio_nbytes,
+						  aiocbp->aiocb64.aio_offset));
+	      else
+		aiocbp->aiocb.__return_value =
+		  TEMP_FAILURE_RETRY (__libc_pwrite (fildes, (const void *)
+					      aiocbp->aiocb.aio_buf,
+					      aiocbp->aiocb.aio_nbytes,
+					      aiocbp->aiocb.aio_offset));
+
+	      if (aiocbp->aiocb.__return_value == -1 && errno == ESPIPE)
+		/* The Linux kernel is different from others.  It returns
+		   ESPIPE if using pwrite on a socket.  Other platforms
+		   simply ignore the offset parameter and behave like
+		   write.  */
+		aiocbp->aiocb.__return_value =
+		  TEMP_FAILURE_RETRY (write (fildes,
+					     (void *) aiocbp->aiocb64.aio_buf,
+					     aiocbp->aiocb64.aio_nbytes));
+	    }
+	  else if (aiocbp->aiocb.aio_lio_opcode == LIO_DSYNC)
+	    aiocbp->aiocb.__return_value =
+	      TEMP_FAILURE_RETRY (fdatasync (fildes));
+	  else if (aiocbp->aiocb.aio_lio_opcode == LIO_SYNC)
+	    aiocbp->aiocb.__return_value =
+	      TEMP_FAILURE_RETRY (fsync (fildes));
+	  else
+	    {
+	      /* This is an invalid opcode.  */
+	      aiocbp->aiocb.__return_value = -1;
+	      __set_errno (EINVAL);
+	    }
+
+	  /* Get the mutex.  */
+	  pthread_mutex_lock (&__aio_requests_mutex);
+
+	  if (aiocbp->aiocb.__return_value == -1)
+	    aiocbp->aiocb.__error_code = errno;
+	  else
+	    aiocbp->aiocb.__error_code = 0;
+
+	  /* Send the signal to notify about finished processing of the
+	     request.  */
+	  __aio_notify (runp);
+
+	  /* For debugging purposes we reset the running flag of the
+	     finished request.  */
+	  assert (runp->running == allocated);
+	  runp->running = done;
+
+	  /* Now dequeue the current request.  */
+	  __aio_remove_request (NULL, runp, 0);
+	  if (runp->next_prio != NULL)
+	    add_request_to_runlist (runp->next_prio);
+
+	  /* Free the old element.  */
+	  __aio_free_request (runp);
+	}
+
+      runp = runlist;
+
+      /* If the runlist is empty, then we sleep for a while, waiting for
+	 something to arrive in it. */
+      if (runp == NULL && optim.aio_idle_time >= 0)
+	{
+	  struct timespec now;
+	  struct timespec wakeup_time;
+
+	  ++idle_thread_count;
+	  __clock_gettime (CLOCK_REALTIME, &now);
+	  wakeup_time.tv_sec = now.tv_sec + optim.aio_idle_time;
+	  wakeup_time.tv_nsec = now.tv_nsec;
+	  if (wakeup_time.tv_nsec >= 1000000000)
+	    {
+	      wakeup_time.tv_nsec -= 1000000000;
+	      ++wakeup_time.tv_sec;
+	    }
+	  pthread_cond_timedwait (&__aio_new_request_notification,
+				  &__aio_requests_mutex,
+				  &wakeup_time);
+	  --idle_thread_count;
+	  runp = runlist;
+	}
+
+      if (runp == NULL)
+	--nthreads;
+      else
+	{
+	  assert (runp->running == yes);
+	  runp->running = allocated;
+	  runlist = runp->next_run;
+
+	  /* If we have a request to process, and there's still another in
+	     the run list, then we need to either wake up or create a new
+	     thread to service the request that is still in the run list. */
+	  if (runlist != NULL)
+	    {
+	      /* There are at least two items in the work queue to work on.
+		 If there are other idle threads, then we should wake them
+		 up for these other work elements; otherwise, we should try
+		 to create a new thread. */
+	      if (idle_thread_count > 0)
+		pthread_cond_signal (&__aio_new_request_notification);
+	      else if (nthreads < optim.aio_threads)
+		{
+		  pthread_t thid;
+		  pthread_attr_t attr;
+
+		  /* Make sure the thread is created detached.  */
+		  pthread_attr_init (&attr);
+		  pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
+
+		  /* Now try to start a thread. If we fail, no big deal,
+		     because we know that there is at least one thread (us)
+		     that is working on AIO operations. */
+		  if (pthread_create (&thid, &attr, handle_fildes_io, NULL)
+		      == 0)
+		    ++nthreads;
+		}
+	    }
+	}
+
+      /* Release the mutex.  */
+      pthread_mutex_unlock (&__aio_requests_mutex);
+    }
+  while (runp != NULL);
+
+  return NULL;
+}
+
+
+/* Free allocated resources.  */
+libc_freeres_fn (free_res)
+{
+  size_t row;
+
+  for (row = 0; row < pool_max_size; ++row)
+    free (pool[row]);
+
+  free (pool);
+}
+
+
+/* Add newrequest to the runlist. The __abs_prio flag of newrequest must
+   be correctly set to do this. Also, you had better set newrequest's
+   "running" flag to "yes" before you release your lock or you'll throw an
+   assertion. */
+static void
+add_request_to_runlist (struct requestlist *newrequest)
+{
+  int prio = newrequest->aiocbp->aiocb.__abs_prio;
+  struct requestlist *runp;
+
+  if (runlist == NULL || runlist->aiocbp->aiocb.__abs_prio < prio)
+    {
+      newrequest->next_run = runlist;
+      runlist = newrequest;
+    }
+  else
+    {
+      runp = runlist;
+
+      while (runp->next_run != NULL
+	     && runp->next_run->aiocbp->aiocb.__abs_prio >= prio)
+	runp = runp->next_run;
+
+      newrequest->next_run = runp->next_run;
+      runp->next_run = newrequest;
+    }
+}
diff --git a/rt/aio_notify.c b/rt/aio_notify.c
index 9d51fd9..a8d6150 100644
--- a/rt/aio_notify.c
+++ b/rt/aio_notify.c
@@ -1,6 +1,7 @@
-/* Notify initiator of AIO request.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Notify initiator of AIO request.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -16,8 +17,141 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <aio.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <unistd.h>
 #include <aio_misc.h>
+#include <signal.h>
 
-/* This file contains only internal functions used by
-   the particular aio_* implementation code.  */
+#ifndef aio_start_notify_thread
+# define aio_start_notify_thread() do { } while (0)
+#endif
+
+struct notify_func
+  {
+    void (*func) (sigval_t);
+    sigval_t value;
+  };
+
+static void *
+notify_func_wrapper (void *arg)
+{
+  aio_start_notify_thread ();
+  struct notify_func *const n = arg;
+  void (*func) (sigval_t) = n->func;
+  sigval_t value = n->value;
+  free (n);
+  (*func) (value);
+  return NULL;
+}
+
+
+int
+__aio_notify_only (struct sigevent *sigev)
+{
+  int result = 0;
+
+  /* Send the signal to notify about finished processing of the request.  */
+  if (__glibc_unlikely (sigev->sigev_notify == SIGEV_THREAD))
+    {
+      /* We have to start a thread.  */
+      pthread_t tid;
+      pthread_attr_t attr, *pattr;
+
+      pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
+      if (pattr == NULL)
+	{
+	  pthread_attr_init (&attr);
+	  pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
+	  pattr = &attr;
+	}
+
+      /* SIGEV may be freed as soon as we return, so we cannot let the
+	 notification thread use that pointer.  Even though a sigval_t is
+	 only one word and the same size as a void *, we cannot just pass
+	 the value through pthread_create as the argument and have the new
+	 thread run the user's function directly, because on some machines
+	 the calling convention for a union like sigval_t is different from
+	 that for a pointer type like void *.  */
+      struct notify_func *nf = malloc (sizeof *nf);
+      if (nf == NULL)
+	result = -1;
+      else
+	{
+	  nf->func = sigev->sigev_notify_function;
+	  nf->value = sigev->sigev_value;
+	  if (pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
+	    {
+	      free (nf);
+	      result = -1;
+	    }
+	}
+    }
+  else if (sigev->sigev_notify == SIGEV_SIGNAL)
+    {
+      /* We have to send a signal.  */
+#if _POSIX_REALTIME_SIGNALS > 0
+      /* Note that the standard gives us the option of using a plain
+	 non-queuing signal here when SA_SIGINFO is not set for the signal.  */
+      if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, getpid ())
+	  < 0)
+	result = -1;
+#else
+      /* There are no queued signals on this system at all.  */
+      result = raise (sigev->sigev_signo);
+#endif
+    }
+
+  return result;
+}
+
+
+void
+__aio_notify (struct requestlist *req)
+{
+  struct waitlist *waitlist;
+  struct aiocb *aiocbp = &req->aiocbp->aiocb;
+
+  if (__aio_notify_only (&aiocbp->aio_sigevent) != 0)
+    {
+      /* XXX What shall we do if already an error is set by
+	 read/write/fsync?  */
+      aiocbp->__error_code = errno;
+      aiocbp->__return_value = -1;
+    }
+
+  /* Now also notify possibly waiting threads.  */
+  waitlist = req->waiting;
+  while (waitlist != NULL)
+    {
+      struct waitlist *next = waitlist->next;
+
+      if (waitlist->sigevp == NULL)
+	{
+	  if (waitlist->result != NULL && aiocbp->__return_value == -1)
+	    *waitlist->result = -1;
+
+#ifdef DONT_NEED_AIO_MISC_COND
+	  AIO_MISC_NOTIFY (waitlist);
+#else
+	  /* Decrement the counter.  */
+	  --*waitlist->counterp;
+
+	  pthread_cond_signal (waitlist->cond);
+#endif
+	}
+      else
+	/* This is part of an asynchronous `lio_listio' operation.  If
+	   this request is the last one, send the signal.  */
+	if (--*waitlist->counterp == 0)
+	  {
+	    __aio_notify_only (waitlist->sigevp);
+	    /* This is tricky.  See lio_listio.c for the reason why
+	       this works.  */
+	    free ((void *) waitlist->counterp);
+	  }
+
+      waitlist = next;
+    }
+}
diff --git a/rt/aio_read.c b/rt/aio_read.c
index fcd5ace..4698e48 100644
--- a/rt/aio_read.c
+++ b/rt/aio_read.c
@@ -1,6 +1,7 @@
-/* Asynchronous read.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Asynchronous read.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -17,18 +18,13 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <aio.h>
-#include <errno.h>
 
-#ifdef BE_AIO64
-#define aiocb		aiocb64
-#define aio_read	aio_read64
-#endif
+#include <aio_misc.h>
+
 
 int
 aio_read (struct aiocb *aiocbp)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  return (__aio_enqueue_request ((aiocb_union *) aiocbp, LIO_READ) == NULL
+	  ? -1 : 0);
 }
-
-stub_warning (aio_read)
diff --git a/rt/aio_read64.c b/rt/aio_read64.c
index e9994ae..26b9b0b 100644
--- a/rt/aio_read64.c
+++ b/rt/aio_read64.c
@@ -1,2 +1,30 @@
-#define BE_AIO64
-#include <aio_read.c>
+/* Asynchronous read, 64bit offset version.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <aio.h>
+
+#include <aio_misc.h>
+
+
+int
+aio_read64 (struct aiocb64 *aiocbp)
+{
+  return (__aio_enqueue_request ((aiocb_union *) aiocbp, LIO_READ64) == NULL
+	  ? -1 : 0);
+}
diff --git a/rt/aio_suspend.c b/rt/aio_suspend.c
index 32f5f7e..6fd5b1b 100644
--- a/rt/aio_suspend.c
+++ b/rt/aio_suspend.c
@@ -1,6 +1,7 @@
-/* Suspend until termination of a requests.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Suspend until termination of a requests.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -27,18 +28,236 @@
 /* And undo the hack.  */
 #undef aio_suspend64
 
+#include <assert.h>
 #include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
 #include <sys/time.h>
 
+#include <libc-lock.h>
+#include <aio_misc.h>
+
+
+struct clparam
+{
+  const struct aiocb *const *list;
+  struct waitlist *waitlist;
+  struct requestlist **requestlist;
+#ifndef DONT_NEED_AIO_MISC_COND
+  pthread_cond_t *cond;
+#endif
+  int nent;
+};
+
+
+static void
+cleanup (void *arg)
+{
+#ifdef DONT_NEED_AIO_MISC_COND
+  /* Acquire the mutex.  If pthread_cond_*wait is used this would
+     happen implicitly.  */
+  pthread_mutex_lock (&__aio_requests_mutex);
+#endif
+
+  const struct clparam *param = (const struct clparam *) arg;
+
+  /* Now remove the entry in the waiting list for all requests
+     which didn't terminate.  */
+  int cnt = param->nent;
+  while (cnt-- > 0)
+    if (param->list[cnt] != NULL
+	&& param->list[cnt]->__error_code == EINPROGRESS)
+      {
+	struct waitlist **listp;
+
+	assert (param->requestlist[cnt] != NULL);
+
+	/* There is the chance that we cannot find our entry anymore. This
+	   could happen if the request terminated and restarted again.  */
+	listp = &param->requestlist[cnt]->waiting;
+	while (*listp != NULL && *listp != &param->waitlist[cnt])
+	  listp = &(*listp)->next;
+
+	if (*listp != NULL)
+	  *listp = (*listp)->next;
+      }
+
+#ifndef DONT_NEED_AIO_MISC_COND
+  /* Release the conditional variable.  */
+  (void) pthread_cond_destroy (param->cond);
+#endif
+
+  /* Release the mutex.  */
+  pthread_mutex_unlock (&__aio_requests_mutex);
+}
+
+#ifdef DONT_NEED_AIO_MISC_COND
+static int
+__attribute__ ((noinline))
+do_aio_misc_wait (unsigned int *cntr, const struct __timespec64 *timeout)
+{
+  int result = 0;
+
+  AIO_MISC_WAIT (result, *cntr, timeout, 1);
+
+  return result;
+}
+#endif
 
 int
-aio_suspend (const struct aiocb *const list[], int nent,
-	     const struct timespec *timeout)
+__aio_suspend_time64 (const struct aiocb *const list[], int nent,
+		      const struct __timespec64 *timeout)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  if (__glibc_unlikely (nent < 0))
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  struct waitlist waitlist[nent];
+  struct requestlist *requestlist[nent];
+#ifndef DONT_NEED_AIO_MISC_COND
+  pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+#endif
+  int cnt;
+  bool any = false;
+  int result = 0;
+  unsigned int cntr = 1;
+
+  /* Request the mutex.  */
+  pthread_mutex_lock (&__aio_requests_mutex);
+
+  /* There is not yet a finished request.  Signal the request that
+     we are working for it.  */
+  for (cnt = 0; cnt < nent; ++cnt)
+    if (list[cnt] != NULL)
+      {
+	if (list[cnt]->__error_code == EINPROGRESS)
+	  {
+	    requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
+
+	    if (requestlist[cnt] != NULL)
+	      {
+#ifndef DONT_NEED_AIO_MISC_COND
+		waitlist[cnt].cond = &cond;
+#endif
+		waitlist[cnt].result = NULL;
+		waitlist[cnt].next = requestlist[cnt]->waiting;
+		waitlist[cnt].counterp = &cntr;
+		waitlist[cnt].sigevp = NULL;
+		requestlist[cnt]->waiting = &waitlist[cnt];
+		any = true;
+	      }
+	    else
+	      /* We will never suspend.  */
+	      break;
+	  }
+	else
+	  /* We will never suspend.  */
+	  break;
+      }
+
+  struct __timespec64 ts;
+  if (timeout != NULL)
+    {
+      __clock_gettime64 (CLOCK_MONOTONIC, &ts);
+      ts.tv_sec += timeout->tv_sec;
+      ts.tv_nsec += timeout->tv_nsec;
+      if (ts.tv_nsec >= 1000000000)
+	{
+	  ts.tv_nsec -= 1000000000;
+	  ts.tv_sec++;
+	}
+    }
+
+  /* Only if none of the entries is NULL or finished to be wait.  */
+  if (cnt == nent && any)
+    {
+      struct clparam clparam =
+	{
+	  .list = list,
+	  .waitlist = waitlist,
+	  .requestlist = requestlist,
+#ifndef DONT_NEED_AIO_MISC_COND
+	  .cond = &cond,
+#endif
+	  .nent = nent
+	};
+
+      pthread_cleanup_push (cleanup, &clparam);
+
+#ifdef DONT_NEED_AIO_MISC_COND
+      result = do_aio_misc_wait (&cntr, timeout == NULL ? NULL : &ts);
+#else
+      struct timespec ts32 = valid_timespec64_to_timespec (ts);
+      result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
+				       timeout == NULL ? NULL : &ts32);
+#endif
+
+      pthread_cleanup_pop (0);
+    }
+
+  /* Now remove the entry in the waiting list for all requests
+     which didn't terminate.  */
+  while (cnt-- > 0)
+    if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
+      {
+	struct waitlist **listp;
+
+	assert (requestlist[cnt] != NULL);
+
+	/* There is the chance that we cannot find our entry anymore. This
+	   could happen if the request terminated and restarted again.  */
+	listp = &requestlist[cnt]->waiting;
+	while (*listp != NULL && *listp != &waitlist[cnt])
+	  listp = &(*listp)->next;
+
+	if (*listp != NULL)
+	  *listp = (*listp)->next;
+      }
+
+#ifndef DONT_NEED_AIO_MISC_COND
+  /* Release the conditional variable.  */
+  if (__glibc_unlikely (pthread_cond_destroy (&cond) != 0))
+    /* This must never happen.  */
+    abort ();
+#endif
+
+  if (result != 0)
+    {
+#ifndef DONT_NEED_AIO_MISC_COND
+      /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
+	 the timeout error report of `pthread_cond_timedwait' to the
+	 form expected from `aio_suspend'.  */
+      if (result == ETIMEDOUT)
+	__set_errno (EAGAIN);
+      else
+#endif
+	__set_errno (result);
+
+      result = -1;
+    }
+
+  /* Release the mutex.  */
+  pthread_mutex_unlock (&__aio_requests_mutex);
+
+  return result;
 }
-weak_alias (aio_suspend, aio_suspend64)
 
-stub_warning (aio_suspend)
-stub_warning (aio_suspend64)
+#if __TIMESIZE != 64
+librt_hidden_def (__aio_suspend_time64)
+
+int
+__aio_suspend (const struct aiocb *const list[], int nent,
+               const struct timespec *timeout)
+{
+  struct __timespec64 ts64;
+
+  if (timeout != NULL)
+    ts64 = valid_timespec_to_timespec64 (*timeout);
+
+  return __aio_suspend_time64 (list, nent, timeout != NULL ? &ts64 : NULL);
+}
+#endif
+weak_alias (__aio_suspend, aio_suspend)
+weak_alias (aio_suspend, aio_suspend64)
diff --git a/rt/aio_write.c b/rt/aio_write.c
index 18a338e..ea55f0d 100644
--- a/rt/aio_write.c
+++ b/rt/aio_write.c
@@ -1,6 +1,7 @@
-/* Asynchronous write.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Asynchronous write.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -17,18 +18,13 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <aio.h>
-#include <errno.h>
 
-#ifdef BE_AIO64
-#define aiocb		aiocb64
-#define aio_write	aio_write64
-#endif
+#include <aio_misc.h>
+
 
 int
 aio_write (struct aiocb *aiocbp)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  return (__aio_enqueue_request ((aiocb_union *) aiocbp, LIO_WRITE) == NULL
+	  ? -1 : 0);
 }
-
-stub_warning (aio_write)
diff --git a/rt/aio_write64.c b/rt/aio_write64.c
index 88d5c00..bd6dd31 100644
--- a/rt/aio_write64.c
+++ b/rt/aio_write64.c
@@ -1,2 +1,30 @@
-#define BE_AIO64
-#include <aio_write.c>
+/* Asynchronous write, 64bit offset version.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <aio.h>
+
+#include <aio_misc.h>
+
+
+int
+aio_write64 (struct aiocb64 *aiocbp)
+{
+  return (__aio_enqueue_request ((aiocb_union *) aiocbp, LIO_WRITE64) == NULL
+	  ? -1 : 0);
+}
diff --git a/rt/lio_listio.c b/rt/lio_listio.c
index db4ce68..2cab3c2 100644
--- a/rt/lio_listio.c
+++ b/rt/lio_listio.c
@@ -1,6 +1,7 @@
-/* Enqueue a list of read or write requests.  Stub version.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Enqueue and list of read or write requests.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -16,25 +17,232 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#ifndef lio_listio
 #include <aio.h>
+#include <assert.h>
 #include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
 
-#ifdef BE_AIO64
-#define lio_listio	lio_listio64
-#define aiocb		aiocb64
-#define aio_read	aio_read64
-#define aio_write	aio_write64
-#define aio_suspend	aio_suspend64
+#include <aio_misc.h>
+
+#define LIO_OPCODE_BASE 0
+#endif
+
+#include <shlib-compat.h>
+
+
+/* We need this special structure to handle asynchronous I/O.  */
+struct async_waitlist
+  {
+    unsigned int counter;
+    struct sigevent sigev;
+    struct waitlist list[0];
+  };
+
+
+/* The code in glibc 2.1 to glibc 2.4 issued only one event when all
+   requests submitted with lio_listio finished.  The existing practice
+   is to issue events for the individual requests as well.  This is
+   what the new code does.  */
+#if SHLIB_COMPAT (librt, GLIBC_2_1, GLIBC_2_4)
+# define LIO_MODE(mode) ((mode) & 127)
+# define NO_INDIVIDUAL_EVENT_P(mode) ((mode) & 128)
+#else
+# define LIO_MODE(mode) mode
+# define NO_INDIVIDUAL_EVENT_P(mode) 0
+#endif
+
+
+static int
+lio_listio_internal (int mode, struct aiocb *const list[], int nent,
+		     struct sigevent *sig)
+{
+  struct sigevent defsigev;
+  struct requestlist *requests[nent];
+  int cnt;
+  volatile unsigned int total = 0;
+  int result = 0;
+
+  if (sig == NULL)
+    {
+      defsigev.sigev_notify = SIGEV_NONE;
+      sig = &defsigev;
+    }
+
+  /* Request the mutex.  */
+  pthread_mutex_lock (&__aio_requests_mutex);
+
+  /* Now we can enqueue all requests.  Since we already acquired the
+     mutex the enqueue function need not do this.  */
+  for (cnt = 0; cnt < nent; ++cnt)
+    if (list[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
+      {
+	if (NO_INDIVIDUAL_EVENT_P (mode))
+	  list[cnt]->aio_sigevent.sigev_notify = SIGEV_NONE;
+
+	requests[cnt] = __aio_enqueue_request ((aiocb_union *) list[cnt],
+					       (list[cnt]->aio_lio_opcode
+						| LIO_OPCODE_BASE));
+
+	if (requests[cnt] != NULL)
+	  /* Successfully enqueued.  */
+	  ++total;
+	else
+	  /* Signal that we've seen an error.  `errno' and the error code
+	     of the aiocb will tell more.  */
+	  result = -1;
+      }
+    else
+      requests[cnt] = NULL;
+
+  if (total == 0)
+    {
+      /* We don't have anything to do except signalling if we work
+	 asynchronously.  */
+
+      /* Release the mutex.  We do this before raising a signal since the
+	 signal handler might do a `siglongjmp' and then the mutex is
+	 locked forever.  */
+      pthread_mutex_unlock (&__aio_requests_mutex);
+
+      if (LIO_MODE (mode) == LIO_NOWAIT)
+	__aio_notify_only (sig);
+
+      return result;
+    }
+  else if (LIO_MODE (mode) == LIO_WAIT)
+    {
+#ifndef DONT_NEED_AIO_MISC_COND
+      pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+      int oldstate;
+#endif
+      struct waitlist waitlist[nent];
+
+      total = 0;
+      for (cnt = 0; cnt < nent; ++cnt)
+	{
+	  assert (requests[cnt] == NULL || list[cnt] != NULL);
+
+	  if (requests[cnt] != NULL && list[cnt]->aio_lio_opcode != LIO_NOP)
+	    {
+#ifndef DONT_NEED_AIO_MISC_COND
+	      waitlist[cnt].cond = &cond;
 #endif
+	      waitlist[cnt].result = &result;
+	      waitlist[cnt].next = requests[cnt]->waiting;
+	      waitlist[cnt].counterp = &total;
+	      waitlist[cnt].sigevp = NULL;
+	      requests[cnt]->waiting = &waitlist[cnt];
+	      ++total;
+	    }
+	}
 
+#ifdef DONT_NEED_AIO_MISC_COND
+      AIO_MISC_WAIT (result, total, NULL, 0);
+#else
+      /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancellation
+	 points we must be careful.  We added entries to the waiting lists
+	 which we must remove.  So defer cancellation for now.  */
+      pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
 
+      while (total > 0)
+	pthread_cond_wait (&cond, &__aio_requests_mutex);
+
+      /* Now it's time to restore the cancellation state.  */
+      pthread_setcancelstate (oldstate, NULL);
+
+      /* Release the conditional variable.  */
+      if (pthread_cond_destroy (&cond) != 0)
+	/* This must never happen.  */
+	abort ();
+#endif
+
+      /* If any of the I/O requests failed, return -1 and set errno.  */
+      if (result != 0)
+	{
+	  __set_errno (result == EINTR ? EINTR : EIO);
+	  result = -1;
+	}
+    }
+  else
+    {
+      struct async_waitlist *waitlist;
+
+      waitlist = (struct async_waitlist *)
+	malloc (sizeof (struct async_waitlist)
+		+ (nent * sizeof (struct waitlist)));
+
+      if (waitlist == NULL)
+	{
+	  __set_errno (EAGAIN);
+	  result = -1;
+	}
+      else
+	{
+	  total = 0;
+
+	  for (cnt = 0; cnt < nent; ++cnt)
+	    {
+	      assert (requests[cnt] == NULL || list[cnt] != NULL);
+
+	      if (requests[cnt] != NULL
+		  && list[cnt]->aio_lio_opcode != LIO_NOP)
+		{
+#ifndef DONT_NEED_AIO_MISC_COND
+		  waitlist->list[cnt].cond = NULL;
+#endif
+		  waitlist->list[cnt].result = NULL;
+		  waitlist->list[cnt].next = requests[cnt]->waiting;
+		  waitlist->list[cnt].counterp = &waitlist->counter;
+		  waitlist->list[cnt].sigevp = &waitlist->sigev;
+		  requests[cnt]->waiting = &waitlist->list[cnt];
+		  ++total;
+		}
+	    }
+
+	  waitlist->counter = total;
+	  waitlist->sigev = *sig;
+	}
+    }
+
+  /* Release the mutex.  */
+  pthread_mutex_unlock (&__aio_requests_mutex);
+
+  return result;
+}
+
+
+#if SHLIB_COMPAT (librt, GLIBC_2_1, GLIBC_2_4)
 int
-lio_listio (int mode,
-	    struct aiocb *const list[], int nent,
-	    struct sigevent *sig)
+attribute_compat_text_section
+__lio_listio_21 (int mode, struct aiocb *const list[], int nent,
+		 struct sigevent *sig)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  /* Check arguments.  */
+  if (mode != LIO_WAIT && mode != LIO_NOWAIT)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  return lio_listio_internal (mode | LIO_NO_INDIVIDUAL_EVENT, list, nent, sig);
 }
+compat_symbol (librt, __lio_listio_21, lio_listio, GLIBC_2_1);
+#endif
 
-stub_warning (lio_listio)
+
+int
+__lio_listio_item_notify (int mode, struct aiocb *const list[], int nent,
+			  struct sigevent *sig)
+{
+    /* Check arguments.  */
+  if (mode != LIO_WAIT && mode != LIO_NOWAIT)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  return lio_listio_internal (mode, list, nent, sig);
+}
+versioned_symbol (librt, __lio_listio_item_notify, lio_listio, GLIBC_2_4);
diff --git a/rt/lio_listio64.c b/rt/lio_listio64.c
index 35a571c..111c883 100644
--- a/rt/lio_listio64.c
+++ b/rt/lio_listio64.c
@@ -1,2 +1,33 @@
-#define BE_AIO64
+/* Enqueue and list of read or write requests, 64bit offset version.
+   Copyright (C) 1997-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <aio.h>
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <aio_misc.h>
+
+#define lio_listio lio_listio64
+#define __lio_listio_21 __lio_listio64_21
+#define __lio_listio_item_notify __lio_listio64_item_notify
+#define aiocb aiocb64
+#define LIO_OPCODE_BASE 128
 #include <lio_listio.c>
diff --git a/rt/timer_create.c b/rt/timer_create.c
index 79d4d18..2808f5b 100644
--- a/rt/timer_create.c
+++ b/rt/timer_create.c
@@ -1,10 +1,11 @@
-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
+/* Copyright (C) 2000-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
 
    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.
+   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
@@ -12,17 +13,154 @@
    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
-   <https://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
+#include <signal.h>
+#include <pthread.h>
 #include <time.h>
+#include <unistd.h>
+
+#include "posix-timer.h"
+
 
 /* Create new per-process timer using CLOCK.  */
 int
 timer_create (clockid_t clock_id, struct sigevent *evp, timer_t *timerid)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  int retval = -1;
+  struct timer_node *newtimer = NULL;
+  struct thread_node *thread = NULL;
+
+  if (0
+#if defined _POSIX_CPUTIME && _POSIX_CPUTIME >= 0
+      || clock_id == CLOCK_PROCESS_CPUTIME_ID
+#endif
+#if defined _POSIX_THREAD_CPUTIME && _POSIX_THREAD_CPUTIME >= 0
+      || clock_id == CLOCK_THREAD_CPUTIME_ID
+#endif
+      )
+    {
+      /* We don't allow timers for CPU clocks.  At least not in the
+	 moment.  */
+      __set_errno (ENOTSUP);
+      return -1;
+    }
+
+  if (clock_id != CLOCK_REALTIME)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  pthread_once (&__timer_init_once_control, __timer_init_once);
+
+  if (__timer_init_failed)
+    {
+      __set_errno (ENOMEM);
+      return -1;
+    }
+
+  pthread_mutex_lock (&__timer_mutex);
+
+  newtimer = __timer_alloc ();
+  if (__glibc_unlikely (newtimer == NULL))
+    {
+      __set_errno (EAGAIN);
+      goto unlock_bail;
+    }
+
+  if (evp != NULL)
+    newtimer->event = *evp;
+  else
+    {
+      newtimer->event.sigev_notify = SIGEV_SIGNAL;
+      newtimer->event.sigev_signo = SIGALRM;
+      newtimer->event.sigev_value.sival_ptr = newtimer;
+      newtimer->event.sigev_notify_function = 0;
+    }
+
+  newtimer->event.sigev_notify_attributes = &newtimer->attr;
+  newtimer->creator_pid = getpid ();
+
+  switch (__builtin_expect (newtimer->event.sigev_notify, SIGEV_SIGNAL))
+    {
+    case SIGEV_NONE:
+    case SIGEV_SIGNAL:
+      /* We have a global thread for delivering timed signals.
+	 If it is not running, try to start it up.  */
+      thread = &__timer_signal_thread_rclk;
+      if (! thread->exists)
+	{
+	  if (__builtin_expect (__timer_thread_start (thread),
+				1) < 0)
+	    {
+	      __set_errno (EAGAIN);
+	      goto unlock_bail;
+            }
+        }
+      break;
+
+    case SIGEV_THREAD:
+      /* Copy over thread attributes or set up default ones.  */
+      if (evp->sigev_notify_attributes)
+	newtimer->attr = *(pthread_attr_t *) evp->sigev_notify_attributes;
+      else
+	pthread_attr_init (&newtimer->attr);
+
+      /* Ensure thread attributes call for deatched thread.  */
+      pthread_attr_setdetachstate (&newtimer->attr, PTHREAD_CREATE_DETACHED);
+
+      /* Try to find existing thread having the right attributes.  */
+      thread = __timer_thread_find_matching (&newtimer->attr, clock_id);
+
+      /* If no existing thread has these attributes, try to allocate one.  */
+      if (thread == NULL)
+	thread = __timer_thread_alloc (&newtimer->attr, clock_id);
+
+      /* Out of luck; no threads are available.  */
+      if (__glibc_unlikely (thread == NULL))
+	{
+	  __set_errno (EAGAIN);
+	  goto unlock_bail;
+	}
+
+      /* If the thread is not running already, try to start it.  */
+      if (! thread->exists
+	  && __builtin_expect (! __timer_thread_start (thread), 0))
+	{
+	  __set_errno (EAGAIN);
+	  goto unlock_bail;
+	}
+      break;
+
+    default:
+      __set_errno (EINVAL);
+      goto unlock_bail;
+    }
+
+  newtimer->clock = clock_id;
+  newtimer->abstime = 0;
+  newtimer->armed = 0;
+  newtimer->thread = thread;
+
+  *timerid = timer_ptr2id (newtimer);
+  retval = 0;
+
+  if (__builtin_expect (retval, 0) == -1)
+    {
+    unlock_bail:
+      if (thread != NULL)
+	__timer_thread_dealloc (thread);
+      if (newtimer != NULL)
+	{
+	  timer_delref (newtimer);
+	  __timer_dealloc (newtimer);
+	}
+    }
+
+  pthread_mutex_unlock (&__timer_mutex);
+
+  return retval;
 }
-stub_warning (timer_create)
diff --git a/rt/timer_delete.c b/rt/timer_delete.c
index 71da429..c6f6d97 100644
--- a/rt/timer_delete.c
+++ b/rt/timer_delete.c
@@ -1,10 +1,11 @@
-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
+/* Copyright (C) 2000-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
 
    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.
+   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
@@ -12,17 +13,56 @@
    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
-   <https://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
 
+#include <assert.h>
 #include <errno.h>
+#include <pthread.h>
 #include <time.h>
 
+#include "posix-timer.h"
+
+
 /* Delete timer TIMERID.  */
 int
 timer_delete (timer_t timerid)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  struct timer_node *timer;
+  int retval = -1;
+
+  pthread_mutex_lock (&__timer_mutex);
+
+  timer = timer_id2ptr (timerid);
+  if (! timer_valid (timer))
+    /* Invalid timer ID or the timer is not in use.  */
+    __set_errno (EINVAL);
+  else
+    {
+      if (timer->armed && timer->thread != NULL)
+	{
+	  struct thread_node *thread = timer->thread;
+	  assert (thread != NULL);
+
+	  /* If thread is cancelled while waiting for handler to terminate,
+	     the mutex is unlocked and timer_delete is aborted.  */
+	  pthread_cleanup_push (__timer_mutex_cancel_handler, &__timer_mutex);
+
+	  /* If timer is currently being serviced, wait for it to finish.  */
+	  while (thread->current_timer == timer)
+	    pthread_cond_wait (&thread->cond, &__timer_mutex);
+
+	  pthread_cleanup_pop (0);
+        }
+
+      /* Remove timer from whatever queue it may be on and deallocate it.  */
+      timer->inuse = TIMER_DELETED;
+      list_unlink_ip (&timer->links);
+      timer_delref (timer);
+      retval = 0;
+    }
+
+  pthread_mutex_unlock (&__timer_mutex);
+
+  return retval;
 }
-stub_warning (timer_delete)
diff --git a/rt/timer_getoverr.c b/rt/timer_getoverr.c
index 3680ba6..c1952f8 100644
--- a/rt/timer_getoverr.c
+++ b/rt/timer_getoverr.c
@@ -1,10 +1,11 @@
-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
+/* Copyright (C) 2000-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
 
    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.
+   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
@@ -12,17 +13,31 @@
    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
-   <https://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
+#include <pthread.h>
 #include <time.h>
 
+#include "posix-timer.h"
+
+
 /* Get expiration overrun for timer TIMERID.  */
 int
 timer_getoverrun (timer_t timerid)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  struct timer_node *timer;
+  int retval = -1;
+
+  pthread_mutex_lock (&__timer_mutex);
+
+  if (! timer_valid (timer = timer_id2ptr (timerid)))
+    __set_errno (EINVAL);
+  else
+    retval = timer->overrun_count;
+
+  pthread_mutex_unlock (&__timer_mutex);
+
+  return retval;
 }
-stub_warning (timer_getoverrun)
diff --git a/rt/timer_gettime.c b/rt/timer_gettime.c
index 7bd9438..dd3b4a6 100644
--- a/rt/timer_gettime.c
+++ b/rt/timer_gettime.c
@@ -1,10 +1,11 @@
-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
+/* Copyright (C) 2000-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
 
    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.
+   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
@@ -12,17 +13,62 @@
    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
-   <https://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
+#include <pthread.h>
 #include <time.h>
 
+#include "posix-timer.h"
+
+
 /* Get current value of timer TIMERID and store it in VLAUE.  */
 int
 timer_gettime (timer_t timerid, struct itimerspec *value)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  struct timer_node *timer;
+  struct timespec now, expiry;
+  int retval = -1, armed = 0, valid;
+  clock_t clock = 0;
+
+  pthread_mutex_lock (&__timer_mutex);
+
+  timer = timer_id2ptr (timerid);
+  valid = timer_valid (timer);
+
+  if (valid) {
+    armed = timer->armed;
+    expiry = timer->expirytime;
+    clock = timer->clock;
+    value->it_interval = timer->value.it_interval;
+  }
+
+  pthread_mutex_unlock (&__timer_mutex);
+
+  if (valid)
+    {
+      if (armed)
+	{
+	  __clock_gettime (clock, &now);
+	  if (timespec_compare (&now, &expiry) < 0)
+	    timespec_sub (&value->it_value, &expiry, &now);
+	  else
+	    {
+	      value->it_value.tv_sec = 0;
+	      value->it_value.tv_nsec = 0;
+	    }
+	}
+      else
+	{
+	  value->it_value.tv_sec = 0;
+	  value->it_value.tv_nsec = 0;
+	}
+
+      retval = 0;
+    }
+  else
+    __set_errno (EINVAL);
+
+  return retval;
 }
-stub_warning (timer_gettime)
diff --git a/rt/timer_settime.c b/rt/timer_settime.c
index cde0e74..c05adf1 100644
--- a/rt/timer_settime.c
+++ b/rt/timer_settime.c
@@ -1,10 +1,11 @@
-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
+/* Copyright (C) 2000-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
+   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
 
    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.
+   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
@@ -12,18 +13,119 @@
    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
-   <https://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
+#include <pthread.h>
 #include <time.h>
 
+#include "posix-timer.h"
+
+
 /* Set timer TIMERID to VALUE, returning old value in OVLAUE.  */
 int
 timer_settime (timer_t timerid, int flags, const struct itimerspec *value,
 	       struct itimerspec *ovalue)
 {
-  __set_errno (ENOSYS);
-  return -1;
+  struct timer_node *timer;
+  struct thread_node *thread = NULL;
+  struct timespec now;
+  int have_now = 0, need_wakeup = 0;
+  int retval = -1;
+
+  timer = timer_id2ptr (timerid);
+  if (timer == NULL)
+    {
+      __set_errno (EINVAL);
+      goto bail;
+    }
+
+  if (! valid_nanoseconds (value->it_interval.tv_nsec)
+      || ! valid_nanoseconds (value->it_value.tv_nsec))
+    {
+      __set_errno (EINVAL);
+      goto bail;
+    }
+
+  /* Will need to know current time since this is a relative timer;
+     might as well make the system call outside of the lock now! */
+
+  if ((flags & TIMER_ABSTIME) == 0)
+    {
+      __clock_gettime (timer->clock, &now);
+      have_now = 1;
+    }
+
+  pthread_mutex_lock (&__timer_mutex);
+  timer_addref (timer);
+
+  /* One final check of timer validity; this one is possible only
+     until we have the mutex, because it accesses the inuse flag. */
+
+  if (! timer_valid(timer))
+    {
+      __set_errno (EINVAL);
+      goto unlock_bail;
+    }
+
+  if (ovalue != NULL)
+    {
+      ovalue->it_interval = timer->value.it_interval;
+
+      if (timer->armed)
+	{
+	  if (! have_now)
+	    {
+	      pthread_mutex_unlock (&__timer_mutex);
+	      __clock_gettime (timer->clock, &now);
+	      have_now = 1;
+	      pthread_mutex_lock (&__timer_mutex);
+	      timer_addref (timer);
+	    }
+
+	  timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
+	}
+      else
+	{
+	  ovalue->it_value.tv_sec = 0;
+	  ovalue->it_value.tv_nsec = 0;
+	}
+    }
+
+  timer->value = *value;
+
+  list_unlink_ip (&timer->links);
+  timer->armed = 0;
+
+  thread = timer->thread;
+
+  /* A value of { 0, 0 } causes the timer to be stopped. */
+  if (value->it_value.tv_sec != 0
+      || __builtin_expect (value->it_value.tv_nsec != 0, 1))
+    {
+      if ((flags & TIMER_ABSTIME) != 0)
+	/* The user specified the expiration time.  */
+	timer->expirytime = value->it_value;
+      else
+	timespec_add (&timer->expirytime, &now, &value->it_value);
+
+      /* Only need to wake up the thread if timer is inserted
+	 at the head of the queue. */
+      if (thread != NULL)
+	need_wakeup = __timer_thread_queue_timer (thread, timer);
+      timer->armed = 1;
+    }
+
+  retval = 0;
+
+unlock_bail:
+  timer_delref (timer);
+  pthread_mutex_unlock (&__timer_mutex);
+
+bail:
+  if (thread != NULL && need_wakeup)
+    __timer_thread_wakeup (thread);
+
+  return retval;
 }
-stub_warning (timer_settime)