+static struct list_head *alloc_hashtable(int size, int *vmalloced)
+{
+ struct list_head *hash;
+ unsigned int i;
+
+ *vmalloced = 0;
+ hash = (void*)__get_free_pages(GFP_KERNEL,
+ get_order(sizeof(struct list_head)
+ * size));
+ if (!hash) {
+ *vmalloced = 1;
+ printk(KERN_WARNING"ip_conntrack: falling back to vmalloc.\n");
+ hash = vmalloc(sizeof(struct list_head) * size);
+ }
+
+ if (hash)
+ for (i = 0; i < size; i++)
+ INIT_LIST_HEAD(&hash[i]);
+
+ return hash;
+}
+
+static int set_hashsize(const char *val, struct kernel_param *kp)
+{
+ int i, bucket, hashsize, vmalloced;
+ int old_vmalloced, old_size;
+ int rnd;
+ struct list_head *hash, *old_hash;
+ struct ip_conntrack_tuple_hash *h;
+
+ /* On boot, we can set this without any fancy locking. */
+ if (!ip_conntrack_htable_size)
+ return param_set_int(val, kp);
+
+ hashsize = simple_strtol(val, NULL, 0);
+ if (!hashsize)
+ return -EINVAL;
+
+ hash = alloc_hashtable(hashsize, &vmalloced);
+ if (!hash)
+ return -ENOMEM;
+
+ /* We have to rehash for the new table anyway, so we also can
+ * use a new random seed */
+ get_random_bytes(&rnd, 4);
+
+ write_lock_bh(&ip_conntrack_lock);
+ for (i = 0; i < ip_conntrack_htable_size; i++) {
+ while (!list_empty(&ip_conntrack_hash[i])) {
+ h = list_entry(ip_conntrack_hash[i].next,
+ struct ip_conntrack_tuple_hash, list);
+ list_del(&h->list);
+ bucket = __hash_conntrack(&h->tuple, hashsize, rnd);
+ list_add_tail(&h->list, &hash[bucket]);
+ }
+ }
+ old_size = ip_conntrack_htable_size;
+ old_vmalloced = ip_conntrack_vmalloc;
+ old_hash = ip_conntrack_hash;
+
+ ip_conntrack_htable_size = hashsize;
+ ip_conntrack_vmalloc = vmalloced;
+ ip_conntrack_hash = hash;
+ ip_conntrack_hash_rnd = rnd;
+ write_unlock_bh(&ip_conntrack_lock);
+
+ free_conntrack_hash(old_hash, old_vmalloced, old_size);
+ return 0;
+}
+
+module_param_call(hashsize, set_hashsize, param_get_uint,
+ &ip_conntrack_htable_size, 0600);