From: Jiri Pirko Date: Tue, 22 Aug 2017 20:46:50 +0000 (+0200) Subject: net: sched: don't do tcf_chain_flush from tcf_chain_destroy X-Git-Tag: v4.13~9^2~56^2 X-Git-Url: https://git.kernelconcepts.de/?p=karo-tx-linux.git;a=commitdiff_plain;h=30d65e8f96ad01d9f998039e9af9ce5545e5a4ee net: sched: don't do tcf_chain_flush from tcf_chain_destroy tcf_chain_flush needs to be called with RTNL. However, on free_tcf-> tcf_action_goto_chain_fini-> tcf_chain_put-> tcf_chain_destroy-> tcf_chain_flush callpath, it is called without RTNL. This issue was notified by following warning: [ 155.599052] WARNING: suspicious RCU usage [ 155.603165] 4.13.0-rc5jiri+ #54 Not tainted [ 155.607456] ----------------------------- [ 155.611561] net/sched/cls_api.c:195 suspicious rcu_dereference_protected() usage! Since on this callpath, the chain is guaranteed to be already empty by check in tcf_chain_put, move the tcf_chain_flush call out and call it only where it is needed - into tcf_block_put. Fixes: db50514f9a9c ("net: sched: add termination action to allow goto chain") Signed-off-by: Jiri Pirko Signed-off-by: David S. Miller --- diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 45cd34eee727..6c5ea84d2682 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -219,8 +219,6 @@ static void tcf_chain_destroy(struct tcf_chain *chain) if (!list_empty(&chain->list)) list_del_init(&chain->list); - tcf_chain_flush(chain); - /* There might still be a reference held when we got here from * tcf_block_put. Wait for the user to drop reference before free. */ @@ -296,8 +294,10 @@ void tcf_block_put(struct tcf_block *block) if (!block) return; - list_for_each_entry_safe(chain, tmp, &block->chain_list, list) + list_for_each_entry_safe(chain, tmp, &block->chain_list, list) { + tcf_chain_flush(chain); tcf_chain_destroy(chain); + } kfree(block); } EXPORT_SYMBOL(tcf_block_put);