ipv6: don't release rt->rt6i_pcpu memory during rt6_release()

After rwlock is replaced with rcu and spinlock, route lookup can happen
simultanously with route deletion.
This patch removes the call to free_percpu(rt->rt6i_pcpu) from
rt6_release() to avoid the race condition between rt6_release() and
rt6_get_pcpu_route(). And as free_percpu(rt->rt6i_pcpu) is already
called in ip6_dst_destroy() after the rcu grace period, it is safe to do
this change.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 9c8e704e6af7d74e36ebd38b9025d88a7e59c806..eee392f7b1f60fdd3c782b4ee5ef4abb9b75dfb0 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -190,9 +190,6 @@ void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
                        *ppcpu_rt = NULL;
                }
        }
-
-       free_percpu(non_pcpu_rt->rt6i_pcpu);
-       non_pcpu_rt->rt6i_pcpu = NULL;
 }
 EXPORT_SYMBOL_GPL(rt6_free_pcpu);