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authorMartin KaFai Lau <kafai@fb.com>2015-09-15 14:30:08 -0700
committerDavid S. Miller <davem@davemloft.net>2015-09-15 14:53:05 -0700
commit8e3d5be7368107f0c27a1f8126d79b01a47e9567 (patch)
tree9930ab62052124ba2e56db04cdbab518a533f4bc /net/ipv6/addrconf.c
parentcdf3464e6c6bd764277cbbe992cd12da735b92fb (diff)
ipv6: Avoid double dst_free
It is a prep work to get dst freeing from fib tree undergo a rcu grace period. The following is a common paradigm: if (ip6_del_rt(rt)) dst_free(rt) which means, if rt cannot be deleted from the fib tree, dst_free(rt) now. 1. We don't know the ip6_del_rt(rt) failure is because it was not managed by fib tree (e.g. DST_NOCACHE) or it had already been removed from the fib tree. 2. If rt had been managed by the fib tree, ip6_del_rt(rt) failure means dst_free(rt) has been called already. A second dst_free(rt) is not always obviously safe. The rt may have been destroyed already. 3. If rt is a DST_NOCACHE, dst_free(rt) should not be called. 4. It is a stopper to make dst freeing from fib tree undergo a rcu grace period. This patch is to use a DST_NOCACHE flag to indicate a rt is not managed by the fib tree. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/addrconf.c')
-rw-r--r--net/ipv6/addrconf.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 030fefdc9aed..900113376d4e 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5127,13 +5127,12 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
rt = addrconf_get_prefix_route(&ifp->peer_addr, 128,
ifp->idev->dev, 0, 0);
- if (rt && ip6_del_rt(rt))
- dst_free(&rt->dst);
+ if (rt)
+ ip6_del_rt(rt);
}
dst_hold(&ifp->rt->dst);
- if (ip6_del_rt(ifp->rt))
- dst_free(&ifp->rt->dst);
+ ip6_del_rt(ifp->rt);
rt_genid_bump_ipv6(net);
break;