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>

1 files changed, 55 insertions, 1 deletions

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 19e44533fb01..4221fd5b1f4b 100644
--- 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)