[ovs-dev] [PATCH 01/13] Upstream GRE: Use RTNL for atomic protocol registration.

[Pravin B Shelar]

From: Pravin Shelar <pshe...@nicira.com>

Currently gre demultiplexer uses its own spin-lock. We should rather
RTNL lock.

Suggested-by: Stephen Hemminger <shemmin...@vyatta.com>
Signed-off-by: Pravin B Shelar <pshe...@nicira.com>
---
 drivers/net/ppp/pptp.c |    5 +++++
 net/ipv4/gre.c         |   18 +++++-------------
 net/ipv4/ip_gre.c      |    5 +++++
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 162464f..b76c151 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -673,11 +673,14 @@ static int __init pptp_init_module(void)
        if (!callid_sock)
                return -ENOMEM;
 
+       rtnl_lock();
        err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
        if (err) {
+               rtnl_unlock();
                pr_err("PPTP: can't add gre protocol\n");
                goto out_mem_free;
        }
+       rtnl_unlock();
 
        err = proto_register(&pptp_sk_proto, 0);
        if (err) {
@@ -707,7 +710,9 @@ static void __exit pptp_exit_module(void)
 {
        unregister_pppox_proto(PX_PROTO_PPTP);
        proto_unregister(&pptp_sk_proto);
+       rtnl_lock();
        gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
+       rtnl_unlock();
        vfree(callid_sock);
 }
 
diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
index 42a4910..5a903dc 100644
--- a/net/ipv4/gre.c
+++ b/net/ipv4/gre.c
@@ -25,23 +25,19 @@
 
 
 static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
-static DEFINE_SPINLOCK(gre_proto_lock);
 
 int gre_add_protocol(const struct gre_protocol *proto, u8 version)
 {
+       ASSERT_RTNL();
        if (version >= GREPROTO_MAX)
                goto err_out;
 
-       spin_lock(&gre_proto_lock);
        if (gre_proto[version])
-               goto err_out_unlock;
+               goto err_out;
 
        RCU_INIT_POINTER(gre_proto[version], proto);
-       spin_unlock(&gre_proto_lock);
        return 0;
 
-err_out_unlock:
-       spin_unlock(&gre_proto_lock);
 err_out:
        return -1;
 }
@@ -49,20 +45,16 @@ EXPORT_SYMBOL_GPL(gre_add_protocol);
 
 int gre_del_protocol(const struct gre_protocol *proto, u8 version)
 {
+       ASSERT_RTNL();
        if (version >= GREPROTO_MAX)
                goto err_out;
 
-       spin_lock(&gre_proto_lock);
-       if (rcu_dereference_protected(gre_proto[version],
-                       lockdep_is_held(&gre_proto_lock)) != proto)
-               goto err_out_unlock;
+       if (rtnl_dereference(gre_proto[version]) != proto)
+               goto err_out;
        RCU_INIT_POINTER(gre_proto[version], NULL);
-       spin_unlock(&gre_proto_lock);
        synchronize_rcu();
        return 0;
 
-err_out_unlock:
-       spin_unlock(&gre_proto_lock);
 err_out:
        return -1;
 }
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index a85ae2f..0d4eecd 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1785,11 +1785,14 @@ static int __init ipgre_init(void)
        if (err < 0)
                return err;
 
+       rtnl_lock();
        err = gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO);
        if (err < 0) {
+               rtnl_unlock();
                pr_info("%s: can't add protocol\n", __func__);
                goto add_proto_failed;
        }
+       rtnl_unlock();
 
        err = rtnl_link_register(&ipgre_link_ops);
        if (err < 0)
@@ -1815,8 +1818,10 @@ static void __exit ipgre_fini(void)
 {
        rtnl_link_unregister(&ipgre_tap_ops);
        rtnl_link_unregister(&ipgre_link_ops);
+       rtnl_lock();
        if (gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0)
                pr_info("%s: can't remove protocol\n", __func__);
+       rtnl_unlock();
        unregister_pernet_device(&ipgre_net_ops);
 }
 
-- 
1.7.1

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