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

From: Andrei Emeltchenko <redacted>

Code which makes changes to RCU list shall be locked.

Signed-off-by: Andrei Emeltchenko <redacted>
---
 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);