[IPSEC]: Perform SA switchover immediately.

When we insert a new xfrm_state which potentially
subsumes an existing one, make sure all cached
bundles are flushed so that the new SA is used
immediately.

Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_policy.c

@@ -1014,13 +1014,12 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
 }
 EXPORT_SYMBOL(__xfrm_route_forward);
 
-/* Optimize later using cookies and generation ids. */
-
 static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie)
 {
-	if (!stale_bundle(dst))
-		return dst;
-
+	/* If it is marked obsolete, which is how we even get here,
+	 * then we have purged it from the policy bundle list and we
+	 * did that for a good reason.
+	 */
 	return NULL;
 }
 
@@ -1104,6 +1103,16 @@ int xfrm_flush_bundles(void)
 	return 0;
 }
 
+static int always_true(struct dst_entry *dst)
+{
+	return 1;
+}
+
+void xfrm_flush_all_bundles(void)
+{
+	xfrm_prune_bundles(always_true);
+}
+
 void xfrm_init_pmtu(struct dst_entry *dst)
 {
 	do {