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Date: Sat, 16 Jun 2012 12:54:48 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: Gao feng <gaofeng@...fujitsu.com>
Cc: netdev@...r.kernel.org, netfilter-devel@...r.kernel.org
Subject: Re: [PATCH net-next v2 04/12] netfilter: regard users as refcount
for l4proto's per-net data
On Sat, Jun 16, 2012 at 11:41:15AM +0800, Gao feng wrote:
> Now, nf_proto_net's users is confusing.
> we should regard it as the refcount for l4proto's per-net data,
> because maybe there are two l4protos use the same per-net data.
>
> so increment pn->users when nf_conntrack_l4proto_register
> success, and decrement it for nf_conntrack_l4_unregister case.
>
> because nf_conntrack_l3proto_ipv[4|6] don't use the same per-net
> data,so we don't need to add a refcnt for their per-net data.
>
> Signed-off-by: Gao feng <gaofeng@...fujitsu.com>
> ---
> net/netfilter/nf_conntrack_proto.c | 71 +++++++++++++++++++++++-------------
> 1 files changed, 46 insertions(+), 25 deletions(-)
>
> diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
> index 1033ee6..86dbf9d 100644
> --- a/net/netfilter/nf_conntrack_proto.c
> +++ b/net/netfilter/nf_conntrack_proto.c
> @@ -39,16 +39,13 @@ static int
> nf_ct_register_sysctl(struct net *net,
> struct ctl_table_header **header,
> const char *path,
> - struct ctl_table *table,
> - unsigned int *users)
> + struct ctl_table *table)
> {
> if (*header == NULL) {
> *header = register_net_sysctl(net, path, table);
> if (*header == NULL)
> return -ENOMEM;
> }
> - if (users != NULL)
> - (*users)++;
>
> return 0;
> }
> @@ -58,7 +55,7 @@ nf_ct_unregister_sysctl(struct ctl_table_header **header,
> struct ctl_table **table,
> unsigned int *users)
> {
> - if (users != NULL && --*users > 0)
> + if (users != NULL && *users > 0)
We're not decrementing users anymore. Use unsigned int users instead.
Pass 0 for the layer 3 case to emulate the users refcnt.
> return;
>
> unregister_net_sysctl_table(*header);
> @@ -191,8 +188,8 @@ static int nf_ct_l3proto_register_sysctl(struct net *net,
> err = nf_ct_register_sysctl(net,
> &in->ctl_table_header,
> l3proto->ctl_table_path,
> - in->ctl_table,
> - NULL);
> + in->ctl_table);
> +
> if (err < 0) {
> kfree(in->ctl_table);
> in->ctl_table = NULL;
> @@ -338,20 +335,17 @@ EXPORT_SYMBOL_GPL(nf_ct_kfree_compat_sysctl_table);
>
> static
> int nf_ct_l4proto_register_sysctl(struct net *net,
> + struct nf_proto_net *pn,
> struct nf_conntrack_l4proto *l4proto)
> {
> int err = 0;
> - struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
> - if (pn == NULL)
> - return 0;
>
> #ifdef CONFIG_SYSCTL
> if (pn->ctl_table != NULL) {
> err = nf_ct_register_sysctl(net,
> &pn->ctl_table_header,
> "net/netfilter",
> - pn->ctl_table,
> - &pn->users);
> + pn->ctl_table);
> if (err < 0) {
> if (!pn->users) {
> kfree(pn->ctl_table);
> @@ -365,8 +359,7 @@ int nf_ct_l4proto_register_sysctl(struct net *net,
> err = nf_ct_register_sysctl(net,
> &pn->ctl_compat_header,
> "net/ipv4/netfilter",
> - pn->ctl_compat_table,
> - NULL);
> + pn->ctl_compat_table);
> if (err == 0)
> goto out;
>
> @@ -383,11 +376,9 @@ out:
>
> static
> void nf_ct_l4proto_unregister_sysctl(struct net *net,
> + struct nf_proto_net *pn,
> struct nf_conntrack_l4proto *l4proto)
> {
> - struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
> - if (pn == NULL)
> - return;
> #ifdef CONFIG_SYSCTL
> if (pn->ctl_table_header != NULL)
> nf_ct_unregister_sysctl(&pn->ctl_table_header,
> @@ -400,8 +391,6 @@ void nf_ct_l4proto_unregister_sysctl(struct net *net,
> &pn->ctl_compat_table,
> NULL);
> #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
> -#else
> - pn->users--;
> #endif /* CONFIG_SYSCTL */
> }
>
> @@ -467,22 +456,33 @@ int nf_conntrack_l4proto_register(struct net *net,
> struct nf_conntrack_l4proto *l4proto)
> {
> int ret = 0;
> +
why this extra line above?
> + struct nf_proto_net *pn = NULL;
> +
> if (l4proto->init_net) {
> ret = l4proto->init_net(net, l4proto->l3proto);
> if (ret < 0)
> - return ret;
> + goto out;
> }
>
> - ret = nf_ct_l4proto_register_sysctl(net, l4proto);
> + pn = nf_ct_l4proto_net(net, l4proto);
> + if (pn == NULL)
> + goto out;
> +
> + ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
> if (ret < 0)
> - return ret;
> + goto out;
>
> if (net == &init_net) {
> ret = nf_conntrack_l4proto_register_net(l4proto);
> - if (ret < 0)
> - nf_ct_l4proto_unregister_sysctl(net, l4proto);
> + if (ret < 0) {
> + nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
> + goto out;
> + }
> }
>
> + pn->users++;
> +out:
> return ret;
> }
> EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
> @@ -507,10 +507,17 @@ nf_conntrack_l4proto_unregister_net(struct nf_conntrack_l4proto *l4proto)
> void nf_conntrack_l4proto_unregister(struct net *net,
> struct nf_conntrack_l4proto *l4proto)
> {
> + struct nf_proto_net *pn = NULL;
> if (net == &init_net)
> nf_conntrack_l4proto_unregister_net(l4proto);
>
> - nf_ct_l4proto_unregister_sysctl(net, l4proto);
> + pn = nf_ct_l4proto_net(net, l4proto);
> + if (pn == NULL)
> + return;
> +
> + pn->users--;
> + nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
> +
> /* Remove all contrack entries for this protocol */
> rtnl_lock();
> nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
> @@ -522,11 +529,15 @@ int nf_conntrack_proto_init(struct net *net)
> {
> unsigned int i;
> int err;
> + struct nf_proto_net *pn = nf_ct_l4proto_net(net,
> + &nf_conntrack_l4proto_generic);
> +
> err = nf_conntrack_l4proto_generic.init_net(net,
> nf_conntrack_l4proto_generic.l3proto);
> if (err < 0)
> return err;
> err = nf_ct_l4proto_register_sysctl(net,
> + pn,
> &nf_conntrack_l4proto_generic);
> if (err < 0)
> return err;
> @@ -536,13 +547,23 @@ int nf_conntrack_proto_init(struct net *net)
> rcu_assign_pointer(nf_ct_l3protos[i],
> &nf_conntrack_l3proto_generic);
> }
> +
> + /* increase generic proto's nf_proto_net refcnt */
> + pn->users++;
> +
> return 0;
> }
>
> void nf_conntrack_proto_fini(struct net *net)
> {
> unsigned int i;
> + struct nf_proto_net *pn = nf_ct_l4proto_net(net,
> + &nf_conntrack_l4proto_generic);
> +
> + /* decrease generic proto's nf_proto_net refcnt */
I asked you to remove this comment, it's superfluous.
> + pn->users--;
> nf_ct_l4proto_unregister_sysctl(net,
> + pn,
> &nf_conntrack_l4proto_generic);
> if (net == &init_net) {
> /* free l3proto protocol tables */
> --
> 1.7.7.6
>
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