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2004-12-10  Ulrich Drepper  <drepper@redhat.com>

	* malloc/arena.c (arena_get2): Prevent endless loop if arenas and
	list lock are taken.
This commit is contained in:
Ulrich Drepper 2004-12-10 11:42:45 +00:00
parent 410b107177
commit 8c7d3691c4
2 changed files with 25 additions and 13 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2004-12-10 Ulrich Drepper <drepper@redhat.com>
* malloc/arena.c (arena_get2): Prevent endless loop if arenas and
list lock are taken.
2004-12-08 Thorsten Kukuk <kukuk@suse.de>
* nis/nss_nisplus/nisplus-netgrp.c (_nss_nisplus_getnetgrent_r):

33
malloc/arena.c
View File

@ -782,9 +782,12 @@ arena_get2(a_tsd, size) mstate a_tsd; size_t size;
}
/* Check the global, circularly linked list for available arenas. */
bool retried = false;
repeat:
do {
if(!mutex_trylock(&a->mutex)) {
if (retried)
(void)mutex_unlock(&list_lock);
THREAD_STAT(++(a->stat_lock_loop));
tsd_setspecific(arena_key, (Void_t *)a);
return a;
@ -796,29 +799,33 @@ arena_get2(a_tsd, size) mstate a_tsd; size_t size;
happen during `atfork', or for example on systems where thread
creation makes it temporarily impossible to obtain _any_
locks. */
if(mutex_trylock(&list_lock)) {
if(!retried && mutex_trylock(&list_lock)) {
/* We will block to not run in a busy loop. */
(void)mutex_lock(&list_lock);
/* Since we blocked there might be an arena available now. */
retried = true;
a = a_tsd;
goto repeat;
}
(void)mutex_unlock(&list_lock);
/* Nothing immediately available, so generate a new arena. */
a = _int_new_arena(size);
if(!a)
return 0;
if(a)
{
tsd_setspecific(arena_key, (Void_t *)a);
mutex_init(&a->mutex);
mutex_lock(&a->mutex); /* remember result */
tsd_setspecific(arena_key, (Void_t *)a);
mutex_init(&a->mutex);
mutex_lock(&a->mutex); /* remember result */
/* Add the new arena to the global list. */
a->next = main_arena.next;
atomic_write_barrier ();
main_arena.next = a;
/* Add the new arena to the global list. */
(void)mutex_lock(&list_lock);
a->next = main_arena.next;
atomic_write_barrier ();
main_arena.next = a;
THREAD_STAT(++(a->stat_lock_loop));
}
(void)mutex_unlock(&list_lock);
THREAD_STAT(++(a->stat_lock_loop));
return a;
}