Em 24/10/2024 15:03, André Almeida escreveu:
Hi Arnd,
Em 24/10/2024 12:57, Arnd Bergmann escreveu:
On Thu, Oct 24, 2024, at 14:57, André Almeida wrote:
This new syscall allows to set multiple list to the same process. There
are two list types: 32 and 64 bit 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_list(tsk, curr->head);
+ else if (curr->list_type == ROBUST_LIST_32BIT)
+ compat_exit_robust_list(tsk, curr->head);
+ curr->head = NULL;
+ }
This looks like the behavior of a 32-bit task using
ROBUST_LIST_64BIT is different on native 32-bit kernels
compared to running on compat mode.
Assuming we want them to behave the same way, did you intend
ROBUST_LIST_64BIT to refer to 64-bit pointers on 32-bit
tasks, or should they use normal word-size pointers?
Oh right, I haven't covered that indeed. I think I would need to have
something like:
static void exit_robust_list_64()
static void exit_robust_list_32()
And then each function would use explicit sizes for pointers. Also, I
would rewrite the conditions to make that every combination of 64/32bit
kernel/app calls the appropriated function.
Something like this:
#ifdef CONFIG_64BIT
if (unlikely(tsk->robust_list)) {
exit_robust_list_64bit(tsk, tsk->robust_list);
tsk->robust_list = NULL;
}
#else
if (unlikely(tsk->robust_list)) {
exit_robust_list_32bit(tsk, tsk->robust_list);
tsk->robust_list = NULL;
}
#endif
#ifdef CONFIG_COMPAT
if (unlikely(tsk->compat_robust_list)) {
exit_robust_32bit(tsk, tsk->compat_robust_list);
tsk->compat_robust_list = NULL;
}
#endif
/* Simplified */
list_for_each_entry_safe(curr, n, list2, list) {
if (curr->list_type == ROBUST_LIST_64BIT)
exit_robust_list_64bit(tsk, curr->head);
else if (curr->list_type == ROBUST_LIST_32BIT)
exit_robust_list_32bit(tsk, curr->head);
}
