Hi Luiz,
On 2024/12/4 1:28, Luiz Augusto von Dentz wrote:
Hi Jiayang,
On Tue, Dec 3, 2024 at 12:19 PM Jiayang Mao <quic_jiaymao@xxxxxxxxxxx> wrote:
Hi Luiz,
On 2024/12/3 4:41, Luiz Augusto von Dentz wrote:
Hi Jiayang,
On Mon, Nov 25, 2024 at 12:51 PM Jiayang Mao <quic_jiaymao@xxxxxxxxxxx> wrote:
Clear the remaining command in cmd_sync_work_list when BT is
performing power off. In some cases, this list is not empty after
power off. BT host will try to send more HCI commands.
This can cause unexpected results.
What commands are in the queue?
If turning off BT during pairing, "hci_acl_create_conn_sync" has chances
to be left in the queue. Then the driver will try to send the HCI
command of creating connection but failed.
There shouldn't be happening though:
/* Terminated due to Power Off */
err = hci_disconnect_all_sync(hdev, HCI_ERROR_REMOTE_POWER_OFF);
if (err)
goto out;
err = hci_dev_close_sync(hdev);
Perhaps there is something attempting to connect after
hci_disconnect_all_sync has completed, in that case there is a bug
around this sequence or we need to check HCI_POWERING_DOWN to not
attempt to process the connection attempts.
After pairing, an L2CAP channel is to be created by l2cap_sock_create
function. It eventually calls hci_connect_acl_sync, which adds
hci_acl_create_conn_sync to the cmd_sync_work_list.
The issue arises if BT is turned off after this addition but before
hci_acl_create_conn_sync is execute.
Your suggestion to check HCI_POWERING_DOWN seems more appropriate
for addressing this issue. We can try incorporating this check into
hci_acl_create_conn_sync.
Signed-off-by: Jiayang Mao <quic_jiaymao@xxxxxxxxxxx>
---
net/bluetooth/hci_sync.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index c86f4e42e..bc622d074 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5139,6 +5139,7 @@ int hci_dev_close_sync(struct hci_dev *hdev)
{
bool auto_off;
int err = 0;
+ struct hci_cmd_sync_work_entry *entry, *tmp;
bt_dev_dbg(hdev, "");
@@ -5258,6 +5259,11 @@ int hci_dev_close_sync(struct hci_dev *hdev)
clear_bit(HCI_RUNNING, &hdev->flags);
hci_sock_dev_event(hdev, HCI_DEV_CLOSE);
+ mutex_lock(&hdev->cmd_sync_work_lock);
+ list_for_each_entry_safe(entry, tmp, &hdev->cmd_sync_work_list, list)
+ _hci_cmd_sync_cancel_entry(hdev, entry, -ECANCELED);
+ mutex_unlock(&hdev->cmd_sync_work_lock);
Seems equivalent to hci_cmd_sync_clear, that said we should have been
running with that lock already, also if there is a sequence like
close/open the close may cancel the subsequent open, so I don't think
we should be canceling every subsequent callback like this.
In hci_cmd_sync_clear, the work cmd_sync_work and reenable_adv_work are
canceled. hci_cmd_sync_clear is not directly called because these two
works should not be canceled during power off.
Do you mean the added code should be moved to other functions to avoid
the risk of lock?
Yes. This change lacks considering sequence of close/open. I will update
the implementation to ensure it does not remove the opening and the
operations after re-opening.
/* After this point our queues are empty and no tasks are scheduled. */
hdev->close(hdev);
--
2.25.1
