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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: db50514f9a ("net: sched: add termination action to allow goto chain")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Pirko 2017-08-22 22:46:50 +02:00 committed by David S. Miller
parent 744a4cf63e
commit 30d65e8f96
1 changed files with 3 additions and 3 deletions
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6
net/sched/cls_api.c
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@ -219,8 +219,6 @@ static void tcf_chain_destroy(struct tcf_chain *chain)
if (!list_empty(&chain->list)) if (!list_empty(&chain->list))
list_del_init(&chain->list); list_del_init(&chain->list);
tcf_chain_flush(chain);
/* There might still be a reference held when we got here from /* There might still be a reference held when we got here from
* tcf_block_put. Wait for the user to drop reference before free. * 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) if (!block)
return; 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); tcf_chain_destroy(chain);
}
kfree(block); kfree(block);
} }
EXPORT_SYMBOL(tcf_block_put); EXPORT_SYMBOL(tcf_block_put);