[ 021/127] l2tp: avoid to use synchronize_rcu in tunnel free function

From: Greg Kroah-Hartman
Date: Fri Sep 28 2012 - 17:10:47 EST


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

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


From: "xeb@xxxxxxx" <xeb@xxxxxxx>

[ Upstream commit 99469c32f79a32d8481f87be0d3c66dad286f4ec ]

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

Signed-off-by: Dmitry Kozlov <xeb@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/l2tp/l2tp_core.c | 3 +--
net/l2tp/l2tp_core.h | 1 +
2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1252,11 +1252,10 @@ static void l2tp_tunnel_free(struct l2tp
/* 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
--- 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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