Hi Marcel,
2009/8/27 Marcel Holtmann <marcel@xxxxxxxxxxxx>:
> Hi Zhu,
>
>> We tried to write a 64k data to rfcomm socket, but it will break
>> before sending all of the data out. The problem is in function
>> rfcomm_sock_sendmsg() in net/bluetooth/rfcomm/sock.c, it breaks after
>> calling sock_alloc_send_skb().
>>
>> static int rfcomm_sock_sendmsg(...)
>> {
>> ...
>> skb = sock_alloc_send_skb(sk, size + RFCOMM_SKB_RESERVE,
>> msg->msg_flags & MSG_DONTWAIT, &err);
>> if (!skb)
>> break;
>> ...
>> }
>>
>> Looks the send buffer is not adequate. Then I increased the send
>> buffer size in function rfcomm_sock_alloc(), build kernel and try
>> again, this time the sendmsg can complete sending all the data.
>>
>> Can we use the setsockopt() method to change the socket's send/receive
>> buffer size, just like the usual tcp/ip socket?
>
> yes we can. Send a patch for it and I am going to review it.
>
> Regards
>
> Marcel
>
>
>
Today I changed the send buffer size but found kernel become very
unstable. It usually crash during sending rfcomm data. Do you know
what's the reason?
Below is what I changed in net/bluetooth/rfcomm/sock.c.
in function rfcomm_sock_alloc(),
change sk->sndbuf
from
sk->sk_sndbuf = RFCOMM_MAX_CREDITS * RFCOMM_DEFAULT_MTU * 10
to
sk->sk_sndbuf = RFCOMM_MAX_CREDITS * RFCOMM_DEFAULT_MTU * 20
Thanks,
Zhu Lan
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