Re: [B.A.T.M.A.N.] [PATCH 1/2] batman-adv: Fix broadcast+ogm queue purging race condition

On Wednesday, February 27, 2013 17:58:15 Linus Lüssing wrote:

+/**

• • batadv_canceled_packets_free - Frees canceled forward packets
• • @head: A list of to be freed forw_packets
• • This function canceles the scheduling of any packet in the provided

list, + * waits for any possibly running packet forwarding thread to finish and + * finally, safely frees this forward packet.

• • This function might sleep.
• */

+static void batadv_canceled_packets_free(struct hlist_head *head) +{

•   struct batadv_forw_packet *forw_packet;
  

•   struct hlist_node *tmp_node, *safe_tmp_node;
  

•   hlist_for_each_entry_safe(forw_packet, tmp_node, safe_tmp_node,
  

head, + canceled_list) {

•           cancel_delayed_work_sync(&forw_packet->delayed_work);
  

•           hlist_del(&forw_packet->canceled_list);
  

•           batadv_forw_packet_free(forw_packet);
  

•   }
  

+}

I don't quite see how your patch can work when only one interface is deactivated and not the mesh as a whole. batadv_purge_outstanding_packets() also is called from batadv_hardif_disable_interface() in which case the broadcast packets re-arm themselves by appending the work item to their respective queues. That is why we have the magic "pending" check in the cleanup functions.

Cheers, Marek