flowcache: Fix resource leaks on namespace exit.

We leak an active timer, the hotcpu notifier and all allocated
resources when we exit a namespace. Fix this by introducing a
flow_cache_fini() function where we release the resources before
we exit.

Fixes: ca925cf153 ("flowcache: Make flow cache name space aware")
Reported-by: Jakub Kicinski <moorray3@wp.pl>
Tested-by: Jakub Kicinski <moorray3@wp.pl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Fan Du <fan.du@windriver.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow.h

@@ -219,6 +219,7 @@ struct flow_cache_object *flow_cache_lookup(struct net *net,
 					    u8 dir, flow_resolve_t resolver,
 					    void *ctx);
 int flow_cache_init(struct net *net);
+void flow_cache_fini(struct net *net);
 
 void flow_cache_flush(struct net *net);
 void flow_cache_flush_deferred(struct net *net);

net/core/flow.c

@@ -484,3 +484,22 @@ err:
 	return -ENOMEM;
 }
 EXPORT_SYMBOL(flow_cache_init);
+
+void flow_cache_fini(struct net *net)
+{
+	int i;
+	struct flow_cache *fc = &net->xfrm.flow_cache_global;
+
+	del_timer_sync(&fc->rnd_timer);
+	unregister_hotcpu_notifier(&fc->hotcpu_notifier);
+
+	for_each_possible_cpu(i) {
+		struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
+		kfree(fcp->hash_table);
+		fcp->hash_table = NULL;
+	}
+
+	free_percpu(fc->percpu);
+	fc->percpu = NULL;
+}
+EXPORT_SYMBOL(flow_cache_fini);

net/xfrm/xfrm_policy.c

@@ -2913,15 +2913,19 @@ static int __net_init xfrm_net_init(struct net *net)
 	rv = xfrm_sysctl_init(net);
 	if (rv < 0)
 		goto out_sysctl;
+	rv = flow_cache_init(net);
+	if (rv < 0)
+		goto out;
 
 	/* Initialize the per-net locks here */
 	spin_lock_init(&net->xfrm.xfrm_state_lock);
 	rwlock_init(&net->xfrm.xfrm_policy_lock);
 	mutex_init(&net->xfrm.xfrm_cfg_mutex);
 
-	flow_cache_init(net);
 	return 0;
 
+out:
+	xfrm_sysctl_fini(net);
 out_sysctl:
 	xfrm_policy_fini(net);
 out_policy:
@@ -2934,6 +2938,7 @@ out_statistics:
 
 static void __net_exit xfrm_net_exit(struct net *net)
 {
+	flow_cache_fini(net);
 	xfrm_sysctl_fini(net);
 	xfrm_policy_fini(net);
 	xfrm_state_fini(net);