[PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Jiayang Mao]

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.

Signed-off-by: Jiayang Mao <quic_jiaymao@quicinc.com>
---
 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);
+
 	/* After this point our queues are empty and no tasks are scheduled. */
 	hdev->close(hdev);
 
-- 
2.25.1

Re: [PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Luiz Augusto von Dentz]

Hi Jiayang,

On Mon, Nov 25, 2024 at 12:51 PM Jiayang Mao <quic_jiaymao@quicinc.com> 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?

> Signed-off-by: Jiayang Mao <quic_jiaymao@quicinc.com>
> ---
>  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.

>         /* After this point our queues are empty and no tasks are scheduled. */
>         hdev->close(hdev);
>
> --
> 2.25.1
>


-- 
Luiz Augusto von Dentz

Re: [PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Jiayang Mao]

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@quicinc.com> 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.
> 
>> Signed-off-by: Jiayang Mao <quic_jiaymao@quicinc.com>
>> ---
>>   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
>>
> 
> 

Re: [PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Luiz Augusto von Dentz]

Hi Jiayang,

On Tue, Dec 3, 2024 at 12:19 PM Jiayang Mao <quic_jiaymao@quicinc.com> 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@quicinc.com> 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.

> >
> >> Signed-off-by: Jiayang Mao <quic_jiaymao@quicinc.com>
> >> ---
> >>   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
> >>
> >
> >
>


-- 
Luiz Augusto von Dentz

Re: [PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Jiayang Mao]

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@quicinc.com> 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@quicinc.com> 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@quicinc.com>
>>>> ---
>>>>    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
>>>>
>>>
>>>
>>
> 
> 

Re: [PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Jiayang Mao]

Hi Luiz,

On 2024/12/4 21:47, Jiayang Mao wrote:
> 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@quicinc.com> 
>> 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@quicinc.com> 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.

Thank you for your attention to this matter. Could you please help to
check my reply? Please let me know if there are any other concerns, or
if I should submit another change to check HCI_POWERING_DOWN in
hci_acl_create_conn_sync.
> 
>>>>
>>>>> Signed-off-by: Jiayang Mao <quic_jiaymao@quicinc.com>
>>>>> ---
>>>>>    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
>>>>>
>>>>
>>>>
>>>
>>
>>
> 
Thanks,
Jiayang Mao

Re: [PATCH v1] Bluetooth: hci_sync: clear cmd_sync_work_list when power off

[Luiz Augusto von Dentz]

Hi,

On Mon, Dec 16, 2024 at 8:36 AM Jiayang Mao <quic_jiaymao@quicinc.com> wrote:
>
> Hi Luiz,
>
> On 2024/12/4 21:47, Jiayang Mao wrote:
> > 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@quicinc.com>
> >> 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@quicinc.com> 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.
>
> Thank you for your attention to this matter. Could you please help to
> check my reply? Please let me know if there are any other concerns, or
> if I should submit another change to check HCI_POWERING_DOWN in
> hci_acl_create_conn_sync.

Yes, please add a check for HCI_POWERING_DOWN, also if you could come
with a test for mgmt-tester to test such a scenario it would be great
since I'm not quite sure how you are able to reproduce this, or is
this a test script that does bluetootctl> connect + power off?

> >
> >>>>
> >>>>> Signed-off-by: Jiayang Mao <quic_jiaymao@quicinc.com>
> >>>>> ---
> >>>>>    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
> >>>>>
> >>>>
> >>>>
> >>>
> >>
> >>
> >
> Thanks,
> Jiayang Mao



-- 
Luiz Augusto von Dentz