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authorUlrich Drepper <drepper@redhat.com>2004-12-10 11:42:45 +0000
committerUlrich Drepper <drepper@redhat.com>2004-12-10 11:42:45 +0000
commit8c7d3691c46e9900d847e084dbc23229419562d6 (patch)
tree491ab2e18249f4371458a138312dca45616dcbf1
parent410b1071776143947bf671f33545c12c6e89dcc0 (diff)
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Update.
2004-12-10 Ulrich Drepper <drepper@redhat.com> * malloc/arena.c (arena_get2): Prevent endless loop if arenas and list lock are taken.
-rw-r--r--ChangeLog5
-rw-r--r--malloc/arena.c33
2 files changed, 25 insertions, 13 deletions
diff --git a/ChangeLog b/ChangeLog
index a38c1d3381..b6689425ec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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 024e191b9e..026f2c7822 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;
}