Hi Peter,
Em 04/11/2024 08:22, Peter Zijlstra escreveu:
On Fri, Nov 01, 2024 at 01:21:46PM -0300, André Almeida wrote:
@@ -1046,24 +1095,44 @@ static inline void exit_pi_state_list(struct task_struct *curr) { }
static void futex_cleanup(struct task_struct *tsk)
{
+ struct robust_list2_entry *curr, *n;
+ struct list_head *list2 = &tsk->robust_list2;
+
#ifdef CONFIG_64BIT
if (unlikely(tsk->robust_list)) {
- exit_robust_list64(tsk);
+ exit_robust_list64(tsk, tsk->robust_list);
tsk->robust_list = NULL;
}
#else
if (unlikely(tsk->robust_list)) {
- exit_robust_list32(tsk);
+ exit_robust_list32(tsk, (struct robust_list_head32 *) tsk->robust_list);
tsk->robust_list = NULL;
}
#endif
#ifdef CONFIG_COMPAT
if (unlikely(tsk->compat_robust_list)) {
- exit_robust_list32(tsk);
+ exit_robust_list32(tsk, tsk->compat_robust_list);
tsk->compat_robust_list = NULL;
}
#endif
+ /*
+ * Walk through the linked list, parsing robust lists and freeing the
+ * allocated lists
+ */
+ if (unlikely(!list_empty(list2))) {
+ list_for_each_entry_safe(curr, n, list2, list) {
+ if (curr->head != NULL) {
+ if (curr->list_type == ROBUST_LIST_64BIT)
+ exit_robust_list64(tsk, curr->head);
+ else if (curr->list_type == ROBUST_LIST_32BIT)
+ exit_robust_list32(tsk, curr->head);
+ curr->head = NULL;
+ }
+ list_del_init(&curr->list);
+ kfree(curr);
+ }
+ }
if (unlikely(!list_empty(&tsk->pi_state_list)))
exit_pi_state_list(tsk);
I'm still digesting this, but the above seems particularly silly.
Should not the legacy lists also be on the list of lists? I mean, it
makes no sense to have two completely separate means of tracking lists.
You are asking if, whenever someone calls set_robust_list() or
compat_set_robust_list() to be inserted into ¤t->robust_list2
instead of using tsk->robust_list and tsk->compat_robust_list?
I was thinking of doing that, but my current implementation has a
kmalloc() call for every insertion, and I wasn't sure if I could add
this new latency to the old set_robust_list() syscall. Assuming it is
usually called just once during the thread initialization perhaps it
shouldn't cause much harm I guess.
