On 21/09/17 09:43, Jiri Pirko wrote:
> From: Yotam Gigi <yot...@mellanox.com>
>
> Make the ipmr module register as a FIB notifier. To do that, implement both
> the ipmr_seq_read and ipmr_dump ops.
>
> The ipmr_seq_read op returns a sequence counter that is incremented on
> every notification related operation done by the ipmr. To implement that,
> add a sequence counter in the netns_ipv4 struct and increment it whenever a
> new MFC route or VIF are added or deleted. The sequence operations are
> protected by the RTNL lock.
>
> The ipmr_dump iterates the list of MFC routes and the list of VIF entries
> and sends notifications about them. The entries dump is done under RCU.
>
> Signed-off-by: Yotam Gigi <yot...@mellanox.com>
> Reviewed-by: Ido Schimmel <ido...@mellanox.com>
> Signed-off-by: Jiri Pirko <j...@mellanox.com>
> ---
> include/linux/mroute.h | 15 ++++++
> include/net/netns/ipv4.h | 3 ++
> net/ipv4/ipmr.c | 135
> ++++++++++++++++++++++++++++++++++++++++++++++-
> 3 files changed, 151 insertions(+), 2 deletions(-)
>
[snip]
> +
> +static int ipmr_dump(struct net *net, struct notifier_block *nb)
> +{
> + struct mr_table *mrt;
> + int err;
> +
> + err = ipmr_rules_dump(net, nb);
> + if (err)
> + return err;
> +
> + ipmr_for_each_table(mrt, net) {
> + struct vif_device *v = &mrt->vif_table[0];
> + struct mfc_cache *mfc;
> + int vifi;
> +
> + /* Notifiy on table VIF entries */
> + for (vifi = 0; vifi < mrt->maxvif; vifi++, v++) {
> + if (!v->dev)
> + continue;
> +
> + call_ipmr_vif_entry_notifier(nb, net, FIB_EVENT_VIF_ADD,
> + v, vifi, mrt->id);
> + }
The VIF table is protected by mrt_lock (rwlock), here with RCU only
you're not guaranteed to keep v->dev. It can become NULL after the check above.
For details you can see vif_delete() in net/ipv4/ipmr.c. You need at least
mrt_lock for reading.
> +
> + /* Notify on table MFC entries */
> + list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list)
> + call_ipmr_mfc_entry_notifier(nb, net,
> + FIB_EVENT_ENTRY_ADD, mfc,
> + mrt->id);
> + }
> +
> + return 0;
> +}
> +
> +static const struct fib_notifier_ops ipmr_notifier_ops_template = {
> + .family = RTNL_FAMILY_IPMR,
> + .fib_seq_read = ipmr_seq_read,
> + .fib_dump = ipmr_dump,
> + .owner = THIS_MODULE,
> +};
> +
> +int __net_init ipmr_notifier_init(struct net *net)
> +{
> + struct fib_notifier_ops *ops;
> +
> + net->ipv4.ipmr_seq = 0;
> +
> + ops = fib_notifier_ops_register(&ipmr_notifier_ops_template, net);
> + if (IS_ERR(ops))
> + return PTR_ERR(ops);
> + net->ipv4.ipmr_notifier_ops = ops;
> +
> + return 0;
> +}
> +
> +static void __net_exit ipmr_notifier_exit(struct net *net)
> +{
> + fib_notifier_ops_unregister(net->ipv4.ipmr_notifier_ops);
> + net->ipv4.ipmr_notifier_ops = NULL;
> +}
> +
> /* Setup for IP multicast routing */
> static int __net_init ipmr_net_init(struct net *net)
> {
> int err;
>
> + err = ipmr_notifier_init(net);
> + if (err)
> + goto ipmr_notifier_fail;
> +
> err = ipmr_rules_init(net);
> if (err < 0)
> - goto fail;
> + goto ipmr_rules_fail;
>
> #ifdef CONFIG_PROC_FS
> err = -ENOMEM;
> @@ -3074,7 +3202,9 @@ static int __net_init ipmr_net_init(struct net *net)
> proc_vif_fail:
> ipmr_rules_exit(net);
> #endif
> -fail:
> +ipmr_rules_fail:
> + ipmr_notifier_exit(net);
> +ipmr_notifier_fail:
> return err;
> }
>
> @@ -3084,6 +3214,7 @@ static void __net_exit ipmr_net_exit(struct net *net)
> remove_proc_entry("ip_mr_cache", net->proc_net);
> remove_proc_entry("ip_mr_vif", net->proc_net);
> #endif
> + ipmr_notifier_exit(net);
> ipmr_rules_exit(net);
> }
>
>
