[PATCH] Bluetooth: Fix inconsistent LE packet sending behaviors

From: Yuxin Wang
Date: Tue Mar 05 2024 - 13:24:11 EST


In the `hci_sched_le` function, the calculation of `quote` within
`hci_chan_sent` may become incorrect after breaking from the inner
while loop. The issue stems from `hci_chan_sent` using `hdev->le_cnt`
instead of the updated `cnt`. As a result, `quote` may exceed `cnt`,
leading to a negative `cnt` and causing further inconsistent behaviors.

This patch modifies `cnt` to be a pointer, aligning with the pattern
used in the nearby `hci_sched_iso` function.

Signed-off-by: Yuxin Wang <yuxinwang9999@xxxxxxxxx>
---
net/bluetooth/hci_core.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 2821a42ce..785a6dde9 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3750,19 +3750,19 @@ static void hci_sched_le(struct hci_dev *hdev)
{
struct hci_chan *chan;
struct sk_buff *skb;
- int quote, cnt, tmp;
+ int quote, *cnt, tmp;

BT_DBG("%s", hdev->name);

if (!hci_conn_num(hdev, LE_LINK))
return;

- cnt = hdev->le_pkts ? hdev->le_cnt : hdev->acl_cnt;
+ cnt = hdev->le_pkts ? &hdev->le_cnt : &hdev->acl_cnt;

- __check_timeout(hdev, cnt, LE_LINK);
+ __check_timeout(hdev, *cnt, LE_LINK);

- tmp = cnt;
- while (cnt && (chan = hci_chan_sent(hdev, LE_LINK, &quote))) {
+ 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))) {
BT_DBG("chan %p skb %p len %d priority %u", chan, skb,
@@ -3777,7 +3777,7 @@ static void hci_sched_le(struct hci_dev *hdev)
hci_send_frame(hdev, skb);
hdev->le_last_tx = jiffies;

- cnt--;
+ (*cnt)--;
chan->sent++;
chan->conn->sent++;

@@ -3787,12 +3787,7 @@ static void hci_sched_le(struct hci_dev *hdev)
}
}

- if (hdev->le_pkts)
- hdev->le_cnt = cnt;
- else
- hdev->acl_cnt = cnt;
-
- if (cnt != tmp)
+ if (*cnt != tmp)
hci_prio_recalculate(hdev, LE_LINK);
}

--
2.39.2