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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: 7bf4796dd0 ("nexthops: add support for replace")
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nikolay Aleksandrov 2021-11-22 17:15:12 +02:00 committed by David S. Miller
parent 4177d5b017
commit 8837cbbf85
4 changed files with 22 additions and 0 deletions
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1
include/net/ip6_fib.h
View File

@ -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,

1
include/net/ipv6_stubs.h
View File

@ -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,

1
net/ipv6/af_inet6.c
View File

@ -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,

19
net/ipv6/route.c
View File

@ -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)