Re: [B.A.T.M.A.N.] [PATCH next] batman-adv: avoid potential race condition when adding a new neighbour

[Marek Lindner <mareklindner@neomailbox.ch>]

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On Friday 24 January 2014 09:58:03 Antonio Quartulli wrote:
> @@ -281,14 +281,23 @@ batadv_iv_ogm_neigh_new(struct batadv_hard_iface
> *hard_iface, neigh_node->orig_node = orig_neigh;
>  	neigh_node->if_incoming = hard_iface;
> 
> -	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
> -		   "Creating new neighbor %pM for orig_node %pM on interface %s\n",
> -		   neigh_addr, orig_node->orig, hard_iface->net_dev->name);
> -
>  	spin_lock_bh(&orig_node->neigh_list_lock);
> -	hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
> +	tmp_neigh_node = batadv_neigh_node_get(orig_node, hard_iface,
> +					       neigh_addr);
> +	if (!tmp_neigh_node) {
> +		hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
> +	} else {
> +		kfree(neigh_node);
> +		neigh_node = tmp_neigh_node;
> +	}

What about hard_iface->refcount ?


>  /**
> + * batadv_neigh_node_get - retrieve a neighbour from the list
> + * @orig_node: originator which the neighbour belongs to
> + * @hard_iface: the interface where this neighbour is connected to
> + * @addr: the address of the neighbour
> + *
> + * Looks for and possibly return a neighbour belonging to this originator
> list + * which is connected through the provided hard interface.

'Looks and return' does not work. Either 'look and return' or 'looks and 
returns'.

Cheers,
Marek

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