linux-kernel - [ 073/135] l2tp: avoid to use synchronize

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Message-Id: <20120917003636.318896221@decadent.org.uk>
Date:	Mon, 17 Sep 2012 01:37:38 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, "xeb@...l.ru" <xeb@...l.ru>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 073/135] l2tp: avoid to use synchronize_rcu in tunnel free  function

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "xeb@...l.ru" <xeb@...l.ru>

[ Upstream commit 99469c32f79a32d8481f87be0d3c66dad286f4ec ]

Avoid to use synchronize_rcu in l2tp_tunnel_free because context may be
atomic.

Signed-off-by: Dmitry Kozlov <xeb@...l.ru>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/l2tp/l2tp_core.c | 3 +--
 net/l2tp/l2tp_core.h | 1 +
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 89ff8c6..7501b22 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1253,11 +1253,10 @@ static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
 	/* Remove from tunnel list */
 	spin_lock_bh(&pn->l2tp_tunnel_list_lock);
 	list_del_rcu(&tunnel->list);
+	kfree_rcu(tunnel, rcu);
 	spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
-	synchronize_rcu();
 
 	atomic_dec(&l2tp_tunnel_count);
-	kfree(tunnel);
 }
 
 /* Create a socket for the tunnel, if one isn't set up by
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index a16a48e..4393794 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -157,6 +157,7 @@ struct l2tp_tunnel_cfg {
 
 struct l2tp_tunnel {
 	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
+	struct rcu_head rcu;
 	rwlock_t		hlist_lock;	/* protect session_hlist */
 	struct hlist_head	session_hlist[L2TP_HASH_SIZE];
 						/* hashed list of sessions,


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