ip_tunnel: fix preempt warning in ip tunnel creation/updating

After the commit e09acddf873b ("ip_tunnel: replace dst_cache with generic
implementation"), a preemption debug warning is triggered on ip4
tunnels updating; the dst cache helper needs to be invoked in unpreemptible
context.

We don't need to load the cache on tunnel update, so this commit fixes
the warning replacing the load with a dst cache reset, which is
preempt safe.

Fixes: e09acddf873b ("ip_tunnel: replace dst_cache with generic implementation")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 6aad0192443d49966785f0de67ee30934775dfca..a69ed94bda1b107634f0aacb6dbedb3d03cc87b0 100644 (file)
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -326,12 +326,12 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
                if (!IS_ERR(rt)) {
                        tdev = rt->dst.dev;
-                       dst_cache_set_ip4(&tunnel->dst_cache, &rt->dst,
-                                         fl4.saddr);
                        ip_rt_put(rt);
                }
                if (dev->type != ARPHRD_ETHER)
                        dev->flags |= IFF_POINTOPOINT;
+
+               dst_cache_reset(&tunnel->dst_cache);
        }
 
        if (!tdev && tunnel->parms.link)