mmu-notifiers: add list_del_init_rcu()

	entry->prev = LIST_POISON2;

	entry->prev = LIST_POISON2;

}

}

/**

 * hlist_del_init_rcu - deletes entry from hash list with re-initialization

 * @n: the element to delete from the hash list.

 *

 * Note: list_unhashed() on the node return true after this. It is

 * useful for RCU based read lockfree traversal if the writer side

 * must know if the list entry is still hashed or already unhashed.

 *

 * In particular, it means that we can not poison the forward pointers

 * that may still be used for walking the hash list and we can only

 * zero the pprev pointer so list_unhashed() will return true after

 * this.

 *

 * The caller must take whatever precautions are necessary (such as

 * holding appropriate locks) to avoid racing with another

 * list-mutation primitive, such as hlist_add_head_rcu() or

 * hlist_del_rcu(), running on this same list.  However, it is

 * perfectly legal to run concurrently with the _rcu list-traversal

 * primitives, such as hlist_for_each_entry_rcu().

 */

static inline void hlist_del_init_rcu(struct hlist_node *n)

{

	if (!hlist_unhashed(n)) {

		__hlist_del(n);

		n->pprev = NULL;

	}

}

/**

/**

 * list_replace_rcu - replace old entry by new one

 * list_replace_rcu - replace old entry by new one

 * @old : the element to be replaced

 * @old : the element to be replaced