On Fri, Dec 09, 2016 at 02:12:03PM +0900, Byungchul Park wrote: > + /* > + * We assign class_idx here redundantly even though following > + * memcpy will cover it, in order to ensure a rcu reader can > + * access the class_idx atomically without lock. > + * > + * Here we assume setting a word-sized variable is atomic. which one, where? > + */ > + xlock->hlock.class_idx = hlock->class_idx; > + gen_id = (unsigned int)atomic_inc_return(&cross_gen_id); > + WRITE_ONCE(xlock->gen_id, gen_id); > + memcpy(&xlock->hlock, hlock, sizeof(struct held_lock)); > + INIT_LIST_HEAD(&xlock->xlock_entry); > + list_add_tail_rcu(&xlock->xlock_entry, &xlocks_head); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>