[atexit] Make hb_languate_item_t *langs freeing threadsafe
Part of https://github.com/harfbuzz/harfbuzz/issues/923
diff --git a/src/hb-common.cc b/src/hb-common.cc
index d1fcf79..ce3d01b 100644
--- a/src/hb-common.cc
+++ b/src/hb-common.cc
@@ -252,11 +252,16 @@
static void
free_langs (void)
{
- while (langs) {
- hb_language_item_t *next = langs->next;
- langs->finish ();
- free (langs);
- langs = next;
+retry:
+ hb_language_item_t *first_lang = (hb_language_item_t *) hb_atomic_ptr_get (&langs);
+ if (!hb_atomic_ptr_cmpexch (&langs, first_lang, nullptr))
+ goto retry;
+
+ while (first_lang) {
+ hb_language_item_t *next = first_lang->next;
+ first_lang->finish ();
+ free (first_lang);
+ first_lang = next;
}
}
#endif
