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>

1 files changed, 555 insertions, 0 deletions

diff --git a/sysdeps/htl/timer_routines.c b/sysdeps/htl/timer_routines.c
new file mode 100644
index 0000000000..059ebef265
--- /dev/null
+++ b/sysdeps/htl/timer_routines.c
@@ -0,0 +1,555 @@
+/* Helper code for POSIX timer implementation on NPTL.
+   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.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysdep.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+#include "posix-timer.h"
+#include <timer_routines.h>
+
+#ifndef DELAYTIMER_MAX
+# define DELAYTIMER_MAX INT_MAX
+#endif
+
+/* Number of threads used.  */
+#define THREAD_MAXNODES	16
+
+/* Array containing the descriptors for the used threads.  */
+static struct thread_node thread_array[THREAD_MAXNODES];
+
+/* Static array with the structures for all the timers.  */
+struct timer_node __timer_array[TIMER_MAX];
+
+/* Global lock to protect operation on the lists.  */
+pthread_mutex_t __timer_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/* Variable to protext initialization.  */
+pthread_once_t __timer_init_once_control = PTHREAD_ONCE_INIT;
+
+/* Nonzero if initialization of timer implementation failed.  */
+int __timer_init_failed;
+
+/* Node for the thread used to deliver signals.  */
+struct thread_node __timer_signal_thread_rclk;
+
+/* Lists to keep free and used timers and threads.  */
+static struct list_head timer_free_list;
+static struct list_head thread_free_list;
+static struct list_head thread_active_list;
+
+
+#ifdef __NR_rt_sigqueueinfo
+extern int __syscall_rt_sigqueueinfo (int, int, siginfo_t *);
+#endif
+
+
+/* List handling functions.  */
+static inline void
+list_append (struct list_head *list, struct list_head *newp)
+{
+  newp->prev = list->prev;
+  newp->next = list;
+  list->prev->next = newp;
+  list->prev = newp;
+}
+
+static inline void
+list_insbefore (struct list_head *list, struct list_head *newp)
+{
+  list_append (list, newp);
+}
+
+/*
+ * Like list_unlink_ip, except that calling it on a node that
+ * is already unlinked is disastrous rather than a noop.
+ */
+
+static inline void
+list_unlink (struct list_head *list)
+{
+  struct list_head *lnext = list->next, *lprev = list->prev;
+
+  lnext->prev = lprev;
+  lprev->next = lnext;
+}
+
+static inline struct list_head *
+list_first (struct list_head *list)
+{
+  return list->next;
+}
+
+static inline struct list_head *
+list_null (struct list_head *list)
+{
+  return list;
+}
+
+static inline struct list_head *
+list_next (struct list_head *list)
+{
+  return list->next;
+}
+
+static inline int
+list_isempty (struct list_head *list)
+{
+  return list->next == list;
+}
+
+
+/* Functions build on top of the list functions.  */
+static inline struct thread_node *
+thread_links2ptr (struct list_head *list)
+{
+  return (struct thread_node *) ((char *) list
+				 - offsetof (struct thread_node, links));
+}
+
+static inline struct timer_node *
+timer_links2ptr (struct list_head *list)
+{
+  return (struct timer_node *) ((char *) list
+				- offsetof (struct timer_node, links));
+}
+
+
+/* Initialize a newly allocated thread structure.  */
+static void
+thread_init (struct thread_node *thread, const pthread_attr_t *attr, clockid_t clock_id)
+{
+  if (attr != NULL)
+    thread->attr = *attr;
+  else
+    {
+      pthread_attr_init (&thread->attr);
+      pthread_attr_setdetachstate (&thread->attr, PTHREAD_CREATE_DETACHED);
+    }
+
+  thread->exists = 0;
+  INIT_LIST_HEAD (&thread->timer_queue);
+  pthread_cond_init (&thread->cond, 0);
+  thread->current_timer = 0;
+  thread->captured = pthread_self ();
+  thread->clock_id = clock_id;
+}
+
+
+/* Initialize the global lists, and acquire global resources.  Error
+   reporting is done by storing a non-zero value to the global variable
+   timer_init_failed.  */
+static void
+init_module (void)
+{
+  int i;
+
+  INIT_LIST_HEAD (&timer_free_list);
+  INIT_LIST_HEAD (&thread_free_list);
+  INIT_LIST_HEAD (&thread_active_list);
+
+  for (i = 0; i < TIMER_MAX; ++i)
+    {
+      list_append (&timer_free_list, &__timer_array[i].links);
+      __timer_array[i].inuse = TIMER_FREE;
+    }
+
+  for (i = 0; i < THREAD_MAXNODES; ++i)
+    list_append (&thread_free_list, &thread_array[i].links);
+
+  thread_init (&__timer_signal_thread_rclk, 0, CLOCK_REALTIME);
+}
+
+
+/* This is a handler executed in a child process after a fork()
+   occurs.  It reinitializes the module, resetting all of the data
+   structures to their initial state.  The mutex is initialized in
+   case it was locked in the parent process.  */
+static void
+reinit_after_fork (void)
+{
+  init_module ();
+  pthread_mutex_init (&__timer_mutex, 0);
+}
+
+
+/* Called once form pthread_once in timer_init. This initializes the
+   module and ensures that reinit_after_fork will be executed in any
+   child process.  */
+void
+__timer_init_once (void)
+{
+  init_module ();
+  pthread_atfork (0, 0, reinit_after_fork);
+}
+
+
+/* Deinitialize a thread that is about to be deallocated.  */
+static void
+thread_deinit (struct thread_node *thread)
+{
+  assert (list_isempty (&thread->timer_queue));
+  pthread_cond_destroy (&thread->cond);
+}
+
+
+/* Allocate a thread structure from the global free list.  Global
+   mutex lock must be held by caller.  The thread is moved to
+   the active list. */
+struct thread_node *
+__timer_thread_alloc (const pthread_attr_t *desired_attr, clockid_t clock_id)
+{
+  struct list_head *node = list_first (&thread_free_list);
+
+  if (node != list_null (&thread_free_list))
+    {
+      struct thread_node *thread = thread_links2ptr (node);
+      list_unlink (node);
+      thread_init (thread, desired_attr, clock_id);
+      list_append (&thread_active_list, node);
+      return thread;
+    }
+
+  return 0;
+}
+
+
+/* Return a thread structure to the global free list.  Global lock
+   must be held by caller.  */
+void
+__timer_thread_dealloc (struct thread_node *thread)
+{
+  thread_deinit (thread);
+  list_unlink (&thread->links);
+  list_append (&thread_free_list, &thread->links);
+}
+
+
+/* Each of our threads which terminates executes this cleanup
+   handler. We never terminate threads ourselves; if a thread gets here
+   it means that the evil application has killed it.  If the thread has
+   timers, these require servicing and so we must hire a replacement
+   thread right away.  We must also unblock another thread that may
+   have been waiting for this thread to finish servicing a timer (see
+   timer_delete()).  */
+
+static void
+thread_cleanup (void *val)
+{
+  if (val != NULL)
+    {
+      struct thread_node *thread = val;
+
+      /* How did the signal thread get killed?  */
+      assert (thread != &__timer_signal_thread_rclk);
+
+      pthread_mutex_lock (&__timer_mutex);
+
+      thread->exists = 0;
+
+      /* We are no longer processing a timer event.  */
+      thread->current_timer = 0;
+
+      if (list_isempty (&thread->timer_queue))
+	__timer_thread_dealloc (thread);
+      else
+	(void) __timer_thread_start (thread);
+
+      pthread_mutex_unlock (&__timer_mutex);
+
+      /* Unblock potentially blocked timer_delete().  */
+      pthread_cond_broadcast (&thread->cond);
+    }
+}
+
+
+/* Handle a timer which is supposed to go off now.  */
+static void
+thread_expire_timer (struct thread_node *self, struct timer_node *timer)
+{
+  self->current_timer = timer; /* Lets timer_delete know timer is running. */
+
+  pthread_mutex_unlock (&__timer_mutex);
+
+  switch (__builtin_expect (timer->event.sigev_notify, SIGEV_SIGNAL))
+    {
+    case SIGEV_NONE:
+      break;
+
+    case SIGEV_SIGNAL:
+#ifdef __NR_rt_sigqueueinfo
+      {
+	siginfo_t info;
+
+	/* First, clear the siginfo_t structure, so that we don't pass our
+	   stack content to other tasks.  */
+	memset (&info, 0, sizeof (siginfo_t));
+	/* We must pass the information about the data in a siginfo_t
+           value.  */
+	info.si_signo = timer->event.sigev_signo;
+	info.si_code = SI_TIMER;
+	info.si_pid = timer->creator_pid;
+	info.si_uid = getuid ();
+	info.si_value = timer->event.sigev_value;
+
+	INLINE_SYSCALL (rt_sigqueueinfo, 3, info.si_pid, info.si_signo, &info);
+      }
+#else
+      if (pthread_kill (self->captured, timer->event.sigev_signo) != 0)
+	{
+	  if (pthread_kill (self->id, timer->event.sigev_signo) != 0)
+	    abort ();
+        }
+#endif
+      break;
+
+    case SIGEV_THREAD:
+      timer->event.sigev_notify_function (timer->event.sigev_value);
+      break;
+
+    default:
+      assert (! "unknown event");
+      break;
+    }
+
+  pthread_mutex_lock (&__timer_mutex);
+
+  self->current_timer = 0;
+
+  pthread_cond_broadcast (&self->cond);
+}
+
+
+/* Thread function; executed by each timer thread. The job of this
+   function is to wait on the thread's timer queue and expire the
+   timers in chronological order as close to their scheduled time as
+   possible.  */
+static void
+__attribute__ ((noreturn))
+thread_func (void *arg)
+{
+  struct thread_node *self = arg;
+
+  /* Register cleanup handler, in case rogue application terminates
+     this thread.  (This cannot happen to __timer_signal_thread, which
+     doesn't invoke application callbacks). */
+
+  pthread_cleanup_push (thread_cleanup, self);
+
+  pthread_mutex_lock (&__timer_mutex);
+
+  while (1)
+    {
+      struct list_head *first;
+      struct timer_node *timer = NULL;
+
+      /* While the timer queue is not empty, inspect the first node.  */
+      first = list_first (&self->timer_queue);
+      if (first != list_null (&self->timer_queue))
+	{
+	  struct timespec now;
+
+	  timer = timer_links2ptr (first);
+
+	  /* This assumes that the elements of the list of one thread
+	     are all for the same clock.  */
+	  __clock_gettime (timer->clock, &now);
+
+	  while (1)
+	    {
+	      /* If the timer is due or overdue, remove it from the queue.
+		 If it's a periodic timer, re-compute its new time and
+		 requeue it.  Either way, perform the timer expiry. */
+	      if (timespec_compare (&now, &timer->expirytime) < 0)
+		break;
+
+	      list_unlink_ip (first);
+
+	      if (__builtin_expect (timer->value.it_interval.tv_sec, 0) != 0
+		  || timer->value.it_interval.tv_nsec != 0)
+		{
+		  timer->overrun_count = 0;
+		  timespec_add (&timer->expirytime, &timer->expirytime,
+				&timer->value.it_interval);
+		  while (timespec_compare (&timer->expirytime, &now) < 0)
+		    {
+		      timespec_add (&timer->expirytime, &timer->expirytime,
+				    &timer->value.it_interval);
+		      if (timer->overrun_count < DELAYTIMER_MAX)
+			++timer->overrun_count;
+		    }
+		  __timer_thread_queue_timer (self, timer);
+		}
+
+	      thread_expire_timer (self, timer);
+
+	      first = list_first (&self->timer_queue);
+	      if (first == list_null (&self->timer_queue))
+		break;
+
+	      timer = timer_links2ptr (first);
+	    }
+	}
+
+      /* If the queue is not empty, wait until the expiry time of the
+	 first node.  Otherwise wait indefinitely.  Insertions at the
+	 head of the queue must wake up the thread by broadcasting
+	 this condition variable.  */
+      if (timer != NULL)
+	pthread_cond_timedwait (&self->cond, &__timer_mutex,
+				&timer->expirytime);
+      else
+	pthread_cond_wait (&self->cond, &__timer_mutex);
+    }
+  /* This macro will never be executed since the while loop loops
+     forever - but we have to add it for proper nesting.  */
+  pthread_cleanup_pop (1);
+}
+
+
+/* Enqueue a timer in wakeup order in the thread's timer queue.
+   Returns 1 if the timer was inserted at the head of the queue,
+   causing the queue's next wakeup time to change. */
+
+int
+__timer_thread_queue_timer (struct thread_node *thread,
+			    struct timer_node *insert)
+{
+  struct list_head *iter;
+  int athead = 1;
+
+  for (iter = list_first (&thread->timer_queue);
+       iter != list_null (&thread->timer_queue);
+        iter = list_next (iter))
+    {
+      struct timer_node *timer = timer_links2ptr (iter);
+
+      if (timespec_compare (&insert->expirytime, &timer->expirytime) < 0)
+	  break;
+      athead = 0;
+    }
+
+  list_insbefore (iter, &insert->links);
+  return athead;
+}
+
+
+/* Start a thread and associate it with the given thread node.  Global
+   lock must be held by caller.  */
+int
+__timer_thread_start (struct thread_node *thread)
+{
+  int retval = 1;
+  sigset_t set, oset;
+
+  assert (!thread->exists);
+  thread->exists = 1;
+
+  sigfillset (&set);
+  pthread_sigmask (SIG_SETMASK, &set, &oset);
+
+  if (pthread_create (&thread->id, &thread->attr,
+		      (void *(*) (void *)) thread_func, thread) != 0)
+    {
+      thread->exists = 0;
+      retval = -1;
+    }
+
+  pthread_sigmask (SIG_SETMASK, &oset, NULL);
+
+  return retval;
+}
+
+
+void
+__timer_thread_wakeup (struct thread_node *thread)
+{
+  pthread_cond_broadcast (&thread->cond);
+}
+
+
+
+/* Search the list of active threads and find one which has matching
+   attributes.  Global mutex lock must be held by caller.  */
+struct thread_node *
+__timer_thread_find_matching (const pthread_attr_t *desired_attr,
+			      clockid_t desired_clock_id)
+{
+  struct list_head *iter = list_first (&thread_active_list);
+
+  while (iter != list_null (&thread_active_list))
+    {
+      struct thread_node *candidate = thread_links2ptr (iter);
+
+      if (thread_attr_compare (desired_attr, &candidate->attr)
+	  && desired_clock_id == candidate->clock_id)
+	return candidate;
+
+      iter = list_next (iter);
+    }
+
+  return NULL;
+}
+
+
+/* Grab a free timer structure from the global free list.  The global
+   lock must be held by the caller.  */
+struct timer_node *
+__timer_alloc (void)
+{
+  struct list_head *node = list_first (&timer_free_list);
+
+  if (node != list_null (&timer_free_list))
+    {
+      struct timer_node *timer = timer_links2ptr (node);
+      list_unlink_ip (node);
+      timer->inuse = TIMER_INUSE;
+      timer->refcount = 1;
+      return timer;
+    }
+
+  return NULL;
+}
+
+
+/* Return a timer structure to the global free list.  The global lock
+   must be held by the caller.  */
+void
+__timer_dealloc (struct timer_node *timer)
+{
+  assert (timer->refcount == 0);
+  timer->thread = NULL;	/* Break association between timer and thread.  */
+  timer->inuse = TIMER_FREE;
+  list_append (&timer_free_list, &timer->links);
+}
+
+
+/* Thread cancellation handler which unlocks a mutex.  */
+void
+__timer_mutex_cancel_handler (void *arg)
+{
+  pthread_mutex_unlock (arg);
+}