From 56f047305dd4b6b61771ac4f523718e4111052a8 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 8 Dec 2015 07:22:01 -0800
Subject: xfrm: add rcu grace period in xfrm_policy_destroy()

We will soon switch sk->sk_policy[] to RCU protection,
as SYNACK packets are sent while listener socket is not locked.

This patch simply adds RCU grace period before struct xfrm_policy
freeing, and the corresponding rcu_head in struct xfrm_policy.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 4a9c21f..8bae1ef 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -548,6 +548,7 @@ struct xfrm_policy {
 	u16			family;
 	struct xfrm_sec_ctx	*security;
 	struct xfrm_tmpl       	xfrm_vec[XFRM_MAX_DEPTH];
+	struct rcu_head		rcu;
 };
 
 static inline struct net *xp_net(const struct xfrm_policy *xp)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 18276f0..f57a571 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -303,6 +303,14 @@ struct xfrm_policy *xfrm_policy_alloc(struct net *net, gfp_t gfp)
 }
 EXPORT_SYMBOL(xfrm_policy_alloc);
 
+static void xfrm_policy_destroy_rcu(struct rcu_head *head)
+{
+	struct xfrm_policy *policy = container_of(head, struct xfrm_policy, rcu);
+
+	security_xfrm_policy_free(policy->security);
+	kfree(policy);
+}
+
 /* Destroy xfrm_policy: descendant resources must be released to this moment. */
 
 void xfrm_policy_destroy(struct xfrm_policy *policy)
@@ -312,8 +320,7 @@ void xfrm_policy_destroy(struct xfrm_policy *policy)
 	if (del_timer(&policy->timer) || del_timer(&policy->polq.hold_timer))
 		BUG();
 
-	security_xfrm_policy_free(policy->security);
-	kfree(policy);
+	call_rcu(&policy->rcu, xfrm_policy_destroy_rcu);
 }
 EXPORT_SYMBOL(xfrm_policy_destroy);
 
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