net: ipv6: add fib6_nh_release_dsts stub

We need a way to release a fib6_nh's per-cpu dsts when replacing
nexthops otherwise we can end up with stale per-cpu dsts which hold net
device references, so add a new IPv6 stub called fib6_nh_release_dsts.
It must be used after an RCU grace period, so no new dsts can be created
through a group's nexthop entry.
Similar to fib6_nh_release it shouldn't be used if fib6_nh_init has failed
so it doesn't need a dummy stub when IPv6 is not enabled.

Fixes: 7bf4796dd099 ("nexthops: add support for replace")
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index c412dde..83b8070 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -485,6 +485,7 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
                 struct fib6_config *cfg, gfp_t gfp_flags,
                 struct netlink_ext_ack *extack);
 void fib6_nh_release(struct fib6_nh *fib6_nh);
+void fib6_nh_release_dsts(struct fib6_nh *fib6_nh);
 
 int call_fib6_entry_notifiers(struct net *net,
                              enum fib_event_type event_type,

diff --git a/include/net/ipv6_stubs.h b/include/net/ipv6_stubs.h
index afbce90..45e0339 100644 (file)
--- a/include/net/ipv6_stubs.h
+++ b/include/net/ipv6_stubs.h
@@ -47,6 +47,7 @@ struct ipv6_stub {
                            struct fib6_config *cfg, gfp_t gfp_flags,
                            struct netlink_ext_ack *extack);
        void (*fib6_nh_release)(struct fib6_nh *fib6_nh);
+       void (*fib6_nh_release_dsts)(struct fib6_nh *fib6_nh);
        void (*fib6_update_sernum)(struct net *net, struct fib6_info *rt);
        int (*ip6_del_rt)(struct net *net, struct fib6_info *rt, bool skip_notify);
        void (*fib6_rt_update)(struct net *net, struct fib6_info *rt,

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 0c4da16..dab4a04 100644 (file)
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -1026,6 +1026,7 @@ static const struct ipv6_stub ipv6_stub_impl = {
        .ip6_mtu_from_fib6 = ip6_mtu_from_fib6,
        .fib6_nh_init      = fib6_nh_init,
        .fib6_nh_release   = fib6_nh_release,
+       .fib6_nh_release_dsts = fib6_nh_release_dsts,
        .fib6_update_sernum = fib6_update_sernum_stub,
        .fib6_rt_update    = fib6_rt_update,
        .ip6_del_rt        = ip6_del_rt,

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 3ae25b8..42d60c7 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3680,6 +3680,25 @@ void fib6_nh_release(struct fib6_nh *fib6_nh)
        fib_nh_common_release(&fib6_nh->nh_common);
 }
 
+void fib6_nh_release_dsts(struct fib6_nh *fib6_nh)
+{
+       int cpu;
+
+       if (!fib6_nh->rt6i_pcpu)
+               return;
+
+       for_each_possible_cpu(cpu) {
+               struct rt6_info *pcpu_rt, **ppcpu_rt;
+
+               ppcpu_rt = per_cpu_ptr(fib6_nh->rt6i_pcpu, cpu);
+               pcpu_rt = xchg(ppcpu_rt, NULL);
+               if (pcpu_rt) {
+                       dst_dev_put(&pcpu_rt->dst);
+                       dst_release(&pcpu_rt->dst);
+               }
+       }
+}
+
 static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
                                              gfp_t gfp_flags,
                                              struct netlink_ext_ack *extack)