[RFCv0 1/5] Bluetooth: Use locks in RCU updater code

[Emeltchenko Andrei <Andrei.Emeltchenko.news@gmail.com>]

From: Andrei Emeltchenko <andrei.emeltchenko@intel.com>

Code which makes changes to RCU list shall be locked.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
---
 net/bluetooth/l2cap_core.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 6991821..f54768e 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -743,13 +743,13 @@ static void l2cap_send_disconn_req(struct l2cap_conn *conn, struct l2cap_chan *c
 /* ---- L2CAP connections ---- */
 static void l2cap_conn_start(struct l2cap_conn *conn)
 {
-	struct l2cap_chan *chan;
+	struct l2cap_chan *chan, *tmp;
 
 	BT_DBG("conn %p", conn);
 
-	rcu_read_lock();
+	mutex_lock(&conn->chan_lock);
 
-	list_for_each_entry_rcu(chan, &conn->chan_l, list) {
+	list_for_each_entry_safe(chan, tmp, &conn->chan_l, list) {
 		struct sock *sk = chan->sk;
 
 		bh_lock_sock(sk);
@@ -829,7 +829,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
 		bh_unlock_sock(sk);
 	}
 
-	rcu_read_unlock();
+	mutex_unlock(&conn->chan_lock);
 }
 
 /* Find socket with cid and source bdaddr.
@@ -1009,6 +1009,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
 
 	kfree_skb(conn->rx_skb);
 
+	mutex_lock(&conn->chan_lock);
+
 	/* Kill channels */
 	list_for_each_entry_safe(chan, l, &conn->chan_l, list) {
 		sk = chan->sk;
@@ -1018,6 +1020,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
 		chan->ops->close(chan->data);
 	}
 
+	mutex_unlock(&conn->chan_lock);
+
 	hci_chan_del(conn->hchan);
 
 	if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_SENT)
@@ -1075,6 +1079,7 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon, u8 status)
 	conn->feat_mask = 0;
 
 	spin_lock_init(&conn->lock);
+	mutex_init(&conn->chan_lock);
 
 	INIT_LIST_HEAD(&conn->chan_l);
 
-- 
1.7.4.1