Re: [PATCH v6 bluetooth-next] 6lowpan: Use skb_cow in IPHC decompression.

[Martin Townsend <martin.townsend@xsilon.com>]

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Hi Jukka,

>From the last trace it looks like a transmit has been started from the receive worker thread.  I notice that both tx and rx use the same workerqueue structure, e.g.

hci_send_xxx <http://lxr.free-electrons.com/ident?i=hci_send_acl>
...
queue_work <http://lxr.free-electrons.com/ident?i=queue_work>(hdev <http://lxr.free-electrons.com/ident?i=hdev>->workqueue <http://lxr.free-electrons.com/ident?i=workqueue>, &hdev <http://lxr.free-electrons.com/ident?i=hdev>->tx_work);



hci_recv_frame <http://lxr.free-electrons.com/ident?i=hci_recv_frame>
...
queue_work <http://lxr.free-electrons.com/ident?i=queue_work>(hdev <http://lxr.free-electrons.com/ident?i=hdev>->workqueue <http://lxr.free-electrons.com/ident?i=workqueue>, &hdev <http://lxr.free-electrons.com/ident?i=hdev>->rx_work <http://lxr.free-electrons.com/ident?i=rx_work>);


Would this cause problems.  I don't know enough about work queues but in workqueue_struct there is a mutex which may be held by the rx worker and if this rx worker start a transmit maybe this would cause the lock?  Could test by creating separate queues for rx and tx?

Anyway just a thought.

- Martin.


On 13/10/14 16:09, Jukka Rissanen wrote:
> Hi Martin,
>
> On ma, 2014-10-13 at 15:56 +0100, Martin Townsend wrote:
>> Hi Jukka,
>>
>> Does this patch help?
> Unfortunately no, I still see inconsistent lock state. It would probably
> have been too easy :)
>
>> ---
>>  net/bluetooth/l2cap_core.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
>> index b6f9777..fb7b2ff 100644
>> --- a/net/bluetooth/l2cap_core.c
>> +++ b/net/bluetooth/l2cap_core.c
>> @@ -5494,6 +5494,7 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn,
>>  	if (credits > max_credits) {
>>  		BT_ERR("LE credits overflow");
>>  		l2cap_send_disconn_req(chan, ECONNRESET);
>> +		l2cap_chan_unlock(chan);
>>  
>>  		/* Return 0 so that we don't trigger an unnecessary
>>  		 * command reject packet.
>
> Cheers,
> Jukka
>
>


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