posix: Consolidate register-atfork

Both htl and nptl uses a different data structure to implement atfork
handlers.  The nptl one was refactored by 27761a1042d to use a dynarray
which simplifies the code.

This patch moves the nptl one to be the generic implementation and
replace Hurd linked one.  Different than previous NPTL, Hurd also uses
a global lock, so performance should be similar.

Checked on x86_64-linux-gnu, i686-linux-gnu, and with a build for
i686-gnu.

2 files changed, 1 insertions, 158 deletions

diff --git a/htl/Makefile b/htl/Makefile
index c15c1b194e..895a6f777c 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -165,7 +165,7 @@ headers :=				\
 
 distribute :=
 
-routines := forward libc_pthread_init alloca_cutoff register-atfork pt-atfork
+routines := forward libc_pthread_init alloca_cutoff pt-atfork
 shared-only-routines = forward
 static-only-routines = pt-atfork
 
diff --git a/htl/register-atfork.c b/htl/register-atfork.c
deleted file mode 100644
index 8be132f981..0000000000
--- a/htl/register-atfork.c
+++ /dev/null
@@ -1,157 +0,0 @@
-/* Atfork handling.  Hurd pthread version.
-   Copyright (C) 2002-2021 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
-   <https://www.gnu.org/licenses/>.  */
-
-#include <errno.h>
-#include <stdlib.h>
-#include <libc-lock.h>
-#include <fork.h>
-
-struct atfork
-{
-  void (*prepare) (void);
-  void (*parent) (void);
-  void (*child) (void);
-  void *dso_handle;
-  struct atfork *prev;
-  struct atfork *next;
-};
-
-/* TODO: better locking */
-__libc_lock_define_initialized (static, atfork_lock);
-static struct atfork *fork_handlers, *fork_last_handler;
-
-static void
-atfork_pthread_prepare (void)
-{
-  struct atfork *handlers, *last_handler;
-
-  __libc_lock_lock (atfork_lock);
-  handlers = fork_handlers;
-  last_handler = fork_last_handler;
-  __libc_lock_unlock (atfork_lock);
-
-  if (last_handler == NULL)
-    return;
-
-  while (1)
-    {
-      if (last_handler->prepare != NULL)
-	last_handler->prepare ();
-      if (last_handler == handlers)
-	break;
-      last_handler = last_handler->prev;
-    }
-}
-text_set_element (_hurd_atfork_prepare_hook, atfork_pthread_prepare);
-
-static void
-atfork_pthread_parent (void)
-{
-  struct atfork *handlers;
-
-  __libc_lock_lock (atfork_lock);
-  handlers = fork_handlers;
-  __libc_lock_unlock (atfork_lock);
-
-  while (handlers != NULL)
-    {
-      if (handlers->parent != NULL)
-	handlers->parent ();
-      handlers = handlers->next;
-    }
-}
-text_set_element (_hurd_atfork_parent_hook, atfork_pthread_parent);
-
-static void
-atfork_pthread_child (void)
-{
-  struct atfork *handlers;
-
-  __libc_lock_lock (atfork_lock);
-  handlers = fork_handlers;
-  __libc_lock_unlock (atfork_lock);
-
-  while (handlers != NULL)
-    {
-      if (handlers->child != NULL)
-	handlers->child ();
-      handlers = handlers->next;
-    }
-}
-text_set_element (_hurd_atfork_child_hook, atfork_pthread_child);
-
-int
-__register_atfork (void (*prepare) (void),
-		   void (*parent) (void),
-		   void (*child) (void),
-		   void *dso_handle)
-{
-  struct atfork *new = malloc (sizeof (*new));
-  if (new == NULL)
-    return errno;
-
-  new->prepare = prepare;
-  new->parent = parent;
-  new->child = child;
-  new->dso_handle = dso_handle;
-  new->next = NULL;
-
-  __libc_lock_lock (atfork_lock);
-  new->prev = fork_last_handler;
-  if (fork_last_handler != NULL)
-    fork_last_handler->next = new;
-  if (fork_handlers == NULL)
-    fork_handlers = new;
-  fork_last_handler = new;
-  __libc_lock_unlock (atfork_lock);
-
-  return 0;
-}
-libc_hidden_def (__register_atfork)
-
-void
-__unregister_atfork (void *dso_handle)
-{
-  struct atfork **handlers, *prev = NULL, *next;
-  __libc_lock_lock (atfork_lock);
-  handlers = &fork_handlers;
-  while (*handlers != NULL)
-    {
-      if ((*handlers)->dso_handle == dso_handle)
-	{
-	  /* Drop this handler from the list.  */
-	  if (*handlers == fork_last_handler)
-	    {
-	      /* Was last, new last is prev, if any.  */
-	      fork_last_handler = prev;
-	    }
-
-	  next = (*handlers)->next;
-	  if (next != NULL)
-	    next->prev = prev;
-	  *handlers = next;
-	}
-      else
-	{
-	  /* Just proceed to next handler.  */
-	  prev = *handlers;
-	  handlers = &prev->next;
-	}
-    }
-  __libc_lock_unlock (atfork_lock);
-}