1 /* Copyright (C) 2002, 2003, 2005, 2007 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
27 /* Lock to protect allocation and deallocation of fork handlers. */
28 int __fork_lock = LLL_LOCK_INITIALIZER;
31 /* Number of pre-allocated handler entries. */
34 /* Memory pool for fork handler structures. */
35 static struct fork_handler_pool
37 struct fork_handler_pool *next;
38 struct fork_handler mem[NHANDLER];
42 static struct fork_handler *
43 fork_handler_alloc (void)
45 struct fork_handler_pool *runp = &fork_handler_pool;
46 struct fork_handler *result = NULL;
51 /* Search for an empty entry. */
52 for (i = 0; i < NHANDLER; ++i)
53 if (runp->mem[i].refcntr == 0)
56 while ((runp = runp->next) != NULL);
58 /* We have to allocate a new entry. */
59 runp = (struct fork_handler_pool *) calloc (1, sizeof (*runp));
62 /* Enqueue the new memory pool into the list. */
63 runp->next = fork_handler_pool.next;
64 fork_handler_pool.next = runp;
66 /* We use the last entry on the page. This means when we start
67 searching from the front the next time we will find the first
72 result = &runp->mem[i];
74 result->need_signal = 0;
83 void (*prepare) (void),
84 void (*parent) (void),
88 /* Get the lock to not conflict with other allocations. */
89 lll_lock (__fork_lock, LLL_PRIVATE);
91 struct fork_handler *newp = fork_handler_alloc ();
95 /* Initialize the new record. */
96 newp->prepare_handler = prepare;
97 newp->parent_handler = parent;
98 newp->child_handler = child;
99 newp->dso_handle = dso_handle;
101 __linkin_atfork (newp);
104 /* Release the lock. */
105 lll_unlock (__fork_lock, LLL_PRIVATE);
107 return newp == NULL ? ENOMEM : 0;
109 libc_hidden_def (__register_atfork)
114 __linkin_atfork (struct fork_handler *newp)
117 newp->next = __fork_handlers;
118 while (catomic_compare_and_exchange_bool_acq (&__fork_handlers,
119 newp, newp->next) != 0);
123 libc_freeres_fn (free_mem)
125 /* Get the lock to not conflict with running forks. */
126 lll_lock (__fork_lock, LLL_PRIVATE);
128 /* No more fork handlers. */
129 __fork_handlers = NULL;
131 /* Free eventually alloated memory blocks for the object pool. */
132 struct fork_handler_pool *runp = fork_handler_pool.next;
134 memset (&fork_handler_pool, '\0', sizeof (fork_handler_pool));
136 /* Release the lock. */
137 lll_unlock (__fork_lock, LLL_PRIVATE);
139 /* We can free the memory after releasing the lock. */
142 struct fork_handler_pool *oldp = runp;