On Saturday, February 23, 2013 02:37:06 Sasha Levin wrote:
I'm confused about how batadv_orig_hash_del_if removes an interface from the hashtable. I see the hashtable is using rcu to protect it, but when we delete an entry we free it straight away by calling batadv_orig_node_del_if() and not going through kfree_rcu().
Is there a reason behind doing that, or might it be the cause of the problem we're seeing here?
Maybe I am overlooking something but it seems to me access to this memory is protected by the same lock: orig_node->ogm_cnt_lock Before batadv_orig_node_del_if() is called this lock is acquired and batadv_slide_own_bcast_window() also attempts acquire the orig_node-
ogm_cnt_lock spinlock before writing to this chunk of memory.
Do we know for certain that batadv_orig_hash_del_if() is involved or is that a guess at this point ? If you ask me the next for-loop in batadv_orig_hash_del_if() looks more suspicious than the first one. The interfaces get renumbered without any protection. Could be a regression from the orig_hash_lock removal (the comments refer to a now inexisting lock).
Cheers, Marek