netdev - Re: [PATCH 3/3] netfilter: xt_CT: remove a compile warning

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Date:	Tue, 3 Apr 2012 12:31:28 +0200
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH 3/3] netfilter: xt_CT: remove a compile warning

On Tue, Apr 03, 2012 at 07:27:50PM +0900, Tetsuo Handa wrote:
> pablo@...filter.org:
> > From: Pablo Neira Ayuso <pablo@...filter.org>
> > 
> > If CONFIG_NF_CONNTRACK_TIMEOUT=n we have following warning :
> > 
> >   CC [M]  net/netfilter/xt_CT.o
> > net/netfilter/xt_CT.c: In function ‘xt_ct_tg_check_v1’:
> > net/netfilter/xt_CT.c:284: warning: label ‘err4’ defined but not used
> > 
> > Reported-by: Eric Dumazet <eric.dumazet@...il.com>
> > Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
> > ---
> >  net/netfilter/xt_CT.c |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> > 
> > diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
> > index 0c8e438..138b75e 100644
> > --- a/net/netfilter/xt_CT.c
> > +++ b/net/netfilter/xt_CT.c
> > @@ -281,8 +281,10 @@ out:
> >  	info->ct = ct;
> >  	return 0;
> >  
> > +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
> >  err4:
> >  	rcu_read_unlock();
> > +#endif
> >  err3:
> >  	nf_conntrack_free(ct);
> >  err2:
> > -- 
> > 1.7.2.5
> 
> Looking at that function:
> 
> 216 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
> 217         if (info->timeout) {
> 218                 typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
> 219                 struct ctnl_timeout *timeout;
> 220                 struct nf_conn_timeout *timeout_ext;
> 221 
> 222                 rcu_read_lock();
> 223                 timeout_find_get =
> 224                         rcu_dereference(nf_ct_timeout_find_get_hook);
> 225 
> 226                 if (timeout_find_get) {
> 227                         const struct ipt_entry *e = par->entryinfo;
> 228                         struct nf_conntrack_l4proto *l4proto;
> 229 
> 230                         if (e->ip.invflags & IPT_INV_PROTO) {
> 231                                 ret = -EINVAL;
> 232                                 pr_info("You cannot use inversion on "
> 233                                          "L4 protocol\n");
> 234                                 goto err4;
> 235                         }
> 236                         timeout = timeout_find_get(info->timeout);
> 237                         if (timeout == NULL) {
> 238                                 ret = -ENOENT;
> 239                                 pr_info("No such timeout policy \"%s\"\n",
> 240                                         info->timeout);
> 241                                 goto err4;
> 242                         }
> 243                         if (timeout->l3num != par->family) {
> 244                                 ret = -EINVAL;
> 245                                 pr_info("Timeout policy `%s' can only be "
> 246                                         "used by L3 protocol number %d\n",
> 247                                         info->timeout, timeout->l3num);
> 248                                 goto err4;
> 249                         }
> 250                         /* Make sure the timeout policy matches any existing
> 251                          * protocol tracker, otherwise default to generic.
> 252                          */
> 253                         l4proto = __nf_ct_l4proto_find(par->family,
> 254                                                        e->ip.proto);
> 255                         if (timeout->l4proto->l4proto != l4proto->l4proto) {
> 256                                 ret = -EINVAL;
> 257                                 pr_info("Timeout policy `%s' can only be "
> 258                                         "used by L4 protocol number %d\n",
> 259                                         info->timeout,
> 260                                         timeout->l4proto->l4proto);
> 261                                 goto err4;
> 262                         }
> 263                         timeout_ext = nf_ct_timeout_ext_add(ct, timeout,
> 264                                                             GFP_KERNEL);
>                             We are under rcu_read_lock() here.

Good catch, that needs to be GFP_ATOMIC. I'll send a follow-up patch
for this.

Thanks.
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