xfrm: Flushing empty SPD generates false events

To see the effect make sure you have an empty SPD.
On window1 "ip xfrm mon" and on window2 issue "ip xfrm policy flush"
You get prompt back in window2 and you see the flush event on window1.
With this fix, you still get prompt on window1 but no event on window2.

Thanks to Alexey Dobriyan for finding a bug in earlier version
when using pfkey to do the flushing.

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/key/af_key.c b/net/key/af_key.c
index c269ce6094d6..a20d2fa88db9 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2735,8 +2735,11 @@ static int pfkey_spdflush(struct sock *sk, struct sk_buff *skb, struct sadb_msg
         audit_info.secid = 0;
         err = xfrm_policy_flush(net, XFRM_POLICY_TYPE_MAIN, &audit_info);
         err2 = unicast_flush_resp(sk, hdr);
-        if (err || err2)
-                return err ? err : err2;
+        if (err || err2) {
+                if (err == -ESRCH) /* empty table - old silent behavior */
+                        return 0;
+                return err;
+        }
 
         c.data.type = XFRM_POLICY_TYPE_MAIN;
         c.event = XFRM_MSG_FLUSHPOLICY;