From: Pravin B Shelar Date: Tue, 12 Jan 2016 19:45:18 +0000 (-0800) Subject: datapath: Fix deadlock on STT device destroy. X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Fovs.git;a=commitdiff_plain;h=fee43fa277f62d1ed7e08b21ece96f4e15df2569 datapath: Fix deadlock on STT device destroy. STT unregisters nf-hook when there are no other STT devices left in the namespace. On some kernel versions the nf-unreg API take RTNL lock, but it is already taken in the tunnel device destroy code path which results in deadlock. To fix the issue I moved the unreg call into net-exit. VMware-BZ: #1582410 Reported-by: Joe Stringer Signed-off-by: Pravin B Shelar Acked-by: Joe Stringer --- diff --git a/datapath/linux/compat/stt.c b/datapath/linux/compat/stt.c index 85ddbe7ca..98d6d5b3c 100644 --- a/datapath/linux/compat/stt.c +++ b/datapath/linux/compat/stt.c @@ -1586,12 +1586,6 @@ static void stt_cleanup(struct net *net) sn->n_tunnels--; if (sn->n_tunnels) goto out; -#ifdef HAVE_NF_REGISTER_NET_HOOK - nf_unregister_net_hook(net, &nf_hook_ops); -#else - nf_unregister_hook(&nf_hook_ops); -#endif - out: n_tunnels--; if (n_tunnels) @@ -1668,6 +1662,7 @@ static int stt_stop(struct net_device *dev) struct net *net = stt_dev->net; list_del_rcu(&stt_dev->up_next); + synchronize_net(); tcp_sock_release(stt_dev->sock); stt_dev->sock = NULL; stt_cleanup(net); @@ -1869,6 +1864,14 @@ static void stt_exit_net(struct net *net) struct net_device *dev, *aux; LIST_HEAD(list); +#ifdef HAVE_NF_REGISTER_NET_HOOK + /* Ideally this should be done from stt_stop(), But on some kernels + * nf-unreg operation needs RTNL-lock, which can cause deallock. + * So it is done from here. */ + if (!list_empty(&nf_hook_ops.list)) + nf_unregister_net_hook(net, &nf_hook_ops); +#endif + rtnl_lock(); /* gather any stt devices that were moved into this ns */ @@ -1908,6 +1911,7 @@ int stt_init_module(void) if (rc) goto out2; + INIT_LIST_HEAD(&nf_hook_ops.list); pr_info("STT tunneling driver\n"); return 0; out2: @@ -1918,6 +1922,10 @@ out1: void stt_cleanup_module(void) { +#ifndef HAVE_NF_REGISTER_NET_HOOK + if (!list_empty(&nf_hook_ops.list)) + nf_unregister_hook(&nf_hook_ops); +#endif rtnl_link_unregister(&stt_link_ops); unregister_pernet_subsys(&stt_net_ops); }