diff options
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | malloc/arena.c | 33 |
2 files changed, 25 insertions, 13 deletions
@@ -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): diff --git a/malloc/arena.c b/malloc/arena.c index 024e191..026f2c7 100644 --- a/malloc/arena.c +++ b/malloc/arena.c @@ -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; } |