Bluetooth: Use RCU to manipulate chan_list

Instead of using tasklet_disable() to prevent acess to the channel use, we
can use RCU and improve the performance of our code.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

2 files changed, 16 insertions, 10 deletions

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index e6d8a220b5d9..b04467674a13 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -960,9 +960,7 @@ struct hci_chan *hci_chan_create(struct hci_conn *conn)
         chan->conn = conn;
         skb_queue_head_init(&chan->data_q);
 
-        tasklet_disable(&hdev->tx_task);
-        list_add(&conn->chan_list, &chan->list);
-        tasklet_enable(&hdev->tx_task);
+        list_add_rcu(&chan->list, &conn->chan_list);
 
         return chan;
 }
@@ -974,9 +972,9 @@ int hci_chan_del(struct hci_chan *chan)
 
         BT_DBG("%s conn %p chan %p", hdev->name, conn, chan);
 
-        tasklet_disable(&hdev->tx_task);
-        list_del(&chan->list);
-        tasklet_enable(&hdev->tx_task);
+        list_del_rcu(&chan->list);
+
+        synchronize_rcu();
 
         skb_queue_purge(&chan->data_q);
         kfree(chan);
@@ -986,10 +984,10 @@ int hci_chan_del(struct hci_chan *chan)
 
 void hci_chan_list_flush(struct hci_conn *conn)
 {
-        struct hci_chan *chan, *tmp;
+        struct hci_chan *chan;
 
         BT_DBG("conn %p", conn);
 
-        list_for_each_entry_safe(chan, tmp, &conn->chan_list, list)
+        list_for_each_entry_rcu(chan, &conn->chan_list, list)
                 hci_chan_del(chan);
 }
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 36763aa59ea1..2c4f32f44569 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2135,7 +2135,9 @@ static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
 
                 conn_num++;
 
-                list_for_each_entry(tmp, &conn->chan_list, list) {
+                rcu_read_lock();
+
+                list_for_each_entry_rcu(tmp, &conn->chan_list, list) {
                         struct sk_buff *skb;
 
                         if (skb_queue_empty(&tmp->data_q))
@@ -2159,6 +2161,8 @@ static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
                         }
                 }
 
+                rcu_read_unlock();
+
                 if (hci_conn_num(hdev, type) == conn_num)
                         break;
         }
@@ -2207,7 +2211,9 @@ static void hci_prio_recalculate(struct hci_dev *hdev, __u8 type)
 
                 num++;
 
-                list_for_each_entry(chan, &conn->chan_list, list) {
+                rcu_read_lock();
+
+                list_for_each_entry_rcu(chan, &conn->chan_list, list) {
                         struct sk_buff *skb;
 
                         if (chan->sent) {
@@ -2228,6 +2234,8 @@ static void hci_prio_recalculate(struct hci_dev *hdev, __u8 type)
                                                                 skb->priority);
                 }
 
+                rcu_read_unlock();
+
                 if (hci_conn_num(hdev, type) == num)
                         break;
         }