ip_tunnel: fix preempt warning in ip tunnel creation/updating

commit f27337e16f2d0e52a8d05ea599ed13cd266ac291 upstream.

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>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 7539e98fdc6a1c48cff0202f6e40976dfe0f36e7..80e2d1b0c08ca2aa4f19ac664a44c8e18e1154b2 100644 (file)
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -327,12 +327,12 @@ 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)