Looks good to me, thanks.
Reviewed-by: Yifeng Sun <pkusunyif...@gmail.com>
On Tue, Jul 10, 2018 at 10:50 AM, William Tu <u9012...@gmail.com> wrote:
> Commit 9f57c67c379d ("gre: Remove support for sharing GRE protocol hook")
> allows only single GRE packet receiver. When upstream kernel's gre module
> is loaded, the gre.ko exclusively becomes the only gre packet receiver,
> preventing OVS kernel module from registering another gre receiver.
>
> We can either try to unload the gre.ko by removing its dependencies,
> or, in this patch, we try to register OVS as only the GRE transmit
> portion when detecting there already exists another GRE receiver.
>
> Signed-off-by: William Tu <u9012...@gmail.com>
> Cc: Greg Rose <gvrose8...@gmail.com>
> Cc: Yifeng Sun <pkusunyif...@gmail.com>
> ---
> datapath/linux/compat/ip_gre.c | 60 ++++++++++++++++++++++++++++++
> +++---------
> datapath/vport.c | 12 ++++++---
> 2 files changed, 56 insertions(+), 16 deletions(-)
>
> diff --git a/datapath/linux/compat/ip_gre.c b/datapath/linux/compat/ip_
> gre.c
> index 92de70127189..1ab798164894 100644
> --- a/datapath/linux/compat/ip_gre.c
> +++ b/datapath/linux/compat/ip_gre.c
> @@ -71,6 +71,7 @@ static void erspan_build_header(struct sk_buff *skb,
> bool truncate, bool is_ipv4);
>
> static struct rtnl_link_ops ipgre_link_ops __read_mostly;
> +static bool ip_gre_loaded = false;
>
> #define ip_gre_calc_hlen rpl_ip_gre_calc_hlen
> static int ip_gre_calc_hlen(__be16 o_flags)
> @@ -1640,25 +1641,57 @@ int rpl_ipgre_init(void)
> int err;
>
> err = register_pernet_device(&ipgre_tap_net_ops);
> - if (err < 0)
> - goto pnet_tap_failed;
> + if (err < 0) {
> + if (err == -EEXIST)
> + goto ip_gre_loaded;
> + else
> + goto pnet_tap_failed;
> + }
>
> err = register_pernet_device(&erspan_net_ops);
> - if (err < 0)
> - goto pnet_erspan_failed;
> + if (err < 0) {
> + if (err == -EEXIST)
> + goto ip_gre_loaded;
> + else
> + goto pnet_erspan_failed;
> + }
>
> err = register_pernet_device(&ipgre_net_ops);
> - if (err < 0)
> - goto pnet_ipgre_failed;
> + if (err < 0) {
> + if (err == -EEXIST)
> + goto ip_gre_loaded;
> + else
> + goto pnet_ipgre_failed;
> + }
>
> err = gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO);
> if (err < 0) {
> pr_info("%s: can't add protocol\n", __func__);
> - goto add_proto_failed;
> + if (err == -EBUSY) {
> + goto ip_gre_loaded;
> + } else {
> + goto add_proto_failed;
> + }
> }
>
> pr_info("GRE over IPv4 tunneling driver\n");
> -
> + ovs_vport_ops_register(&ovs_ipgre_vport_ops);
> + ovs_vport_ops_register(&ovs_erspan_vport_ops);
> + return 0;
> +
> +ip_gre_loaded:
> + /* Since GRE only allows single receiver to be registerd,
> + * we skip here so only gre transmit works, see:
> + *
> + * commit 9f57c67c379d88a10e8ad676426fee5ae7341b14
> + * Author: Pravin B Shelar <pshe...@nicira.com>
> + * Date: Fri Aug 7 23:51:52 2015 -0700
> + * gre: Remove support for sharing GRE protocol hook
> + *
> + * OVS GRE receive part is disabled.
> + */
> + pr_info("GRE TX only over IPv4 tunneling driver\n");
> + ip_gre_loaded = true;
> ovs_vport_ops_register(&ovs_ipgre_vport_ops);
> ovs_vport_ops_register(&ovs_erspan_vport_ops);
> return 0;
> @@ -1678,10 +1711,13 @@ void rpl_ipgre_fini(void)
> {
> ovs_vport_ops_unregister(&ovs_erspan_vport_ops);
> ovs_vport_ops_unregister(&ovs_ipgre_vport_ops);
> - gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
> - unregister_pernet_device(&ipgre_net_ops);
> - unregister_pernet_device(&erspan_net_ops);
> - unregister_pernet_device(&ipgre_tap_net_ops);
> +
> + if (!ip_gre_loaded) {
> + gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
> + unregister_pernet_device(&ipgre_net_ops);
> + unregister_pernet_device(&erspan_net_ops);
> + unregister_pernet_device(&ipgre_tap_net_ops);
> + }
> }
>
> #endif
> diff --git a/datapath/vport.c b/datapath/vport.c
> index 02f6b56d3243..05dd9dc2a149 100644
> --- a/datapath/vport.c
> +++ b/datapath/vport.c
> @@ -66,11 +66,15 @@ int ovs_vport_init(void)
> if (err)
> goto err_lisp;
> err = gre_init();
> - if (err && err != -EEXIST)
> + if (err && err != -EEXIST) {
> goto err_gre;
> - else if (err == -EEXIST)
> - pr_warn("Cannot take GRE protocol entry - The ERSPAN
> feature may not be supported\n");
> - else {
> + } else {
> + if (err == -EEXIST) {
> + pr_warn("Cannot take GRE protocol entry"\
> + "- The ERSPAN feature may not be
> supported\n");
> + /* continue GRE tx */
> + }
> +
> err = ipgre_init();
> if (err && err != -EEXIST)
> goto err_ipgre;
> --
> 2.7.4
>
>
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