Bluetooth: recalculate priorities when channels are starving

To avoid starvation the priority is recalculated so that the starving
channels are promoted to HCI_PRIO_MAX - 1 (6).

HCI_PRIO_MAX (7) is considered special, because it requires CAP_NET_ADMIN
capability which can be used to provide more guaranties, so it is not used
when promoting.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 19e44533fb01223466c20449a5b89754c9526036..4221fd5b1f4bbe9ce2c67091cd44a282c87ec2e7 100644 (file)
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2170,6 +2170,53 @@ static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
        return chan;
 }
 
+static void hci_prio_recalculate(struct hci_dev *hdev, __u8 type)
+{
+       struct hci_conn_hash *h = &hdev->conn_hash;
+       struct hci_conn *conn;
+       int num = 0;
+
+       BT_DBG("%s", hdev->name);
+
+       list_for_each_entry(conn, &h->list, list) {
+               struct hci_chan_hash *ch;
+               struct hci_chan *chan;
+
+               if (conn->type != type)
+                       continue;
+
+               if (conn->state != BT_CONNECTED && conn->state != BT_CONFIG)
+                       continue;
+
+               num++;
+
+               ch = &conn->chan_hash;
+               list_for_each_entry(chan, &ch->list, list) {
+                       struct sk_buff *skb;
+
+                       if (chan->sent) {
+                               chan->sent = 0;
+                               continue;
+                       }
+
+                       if (skb_queue_empty(&chan->data_q))
+                               continue;
+
+                       skb = skb_peek(&chan->data_q);
+                       if (skb->priority >= HCI_PRIO_MAX - 1)
+                               continue;
+
+                       skb->priority = HCI_PRIO_MAX - 1;
+
+                       BT_DBG("chan %p skb %p promoted to %d", chan, skb,
+                                                               skb->priority);
+               }
+
+               if (hci_conn_num(hdev, type) == num)
+                       break;
+       }
+}
+
 static inline void hci_sched_acl(struct hci_dev *hdev)
 {
        struct hci_chan *chan;
@@ -2215,6 +2262,9 @@ static inline void hci_sched_acl(struct hci_dev *hdev)
                        chan->conn->sent++;
                }
        }
+
+       if (cnt != hdev->acl_cnt)
+               hci_prio_recalculate(hdev, ACL_LINK);
 }
 
 /* Schedule SCO */
@@ -2268,7 +2318,7 @@ static inline void hci_sched_le(struct hci_dev *hdev)
 {
        struct hci_chan *chan;
        struct sk_buff *skb;
-       int quote, cnt;
+       int quote, cnt, tmp;
 
        BT_DBG("%s", hdev->name);
 
@@ -2284,6 +2334,7 @@ static inline void hci_sched_le(struct hci_dev *hdev)
        }
 
        cnt = hdev->le_pkts ? hdev->le_cnt : hdev->acl_cnt;
+       tmp = cnt;
        while (cnt && (chan = hci_chan_sent(hdev, LE_LINK, &quote))) {
                u32 priority = (skb_peek(&chan->data_q))->priority;
                while (quote-- && (skb = skb_peek(&chan->data_q))) {
@@ -2309,6 +2360,9 @@ static inline void hci_sched_le(struct hci_dev *hdev)
                hdev->le_cnt = cnt;
        else
                hdev->acl_cnt = cnt;
+
+       if (cnt != tmp)
+               hci_prio_recalculate(hdev, LE_LINK);
 }
 
 static void hci_tx_task(unsigned long arg)