Re: [PATCHv1 5/5] Bluetooth: EWS: prevent unneeded fragmentation in l2cap

[Gustavo Padovan <padovan@profusion.mobi>]

Hi Andrei,

* Emeltchenko Andrei <Andrei.Emeltchenko.news@gmail.com> [2011-09-16 14:43:17 +0300]:

> Hi Gustavo,
> 
> On Wed, Sep 14, 2011 at 12:51:04AM -0300, Gustavo Padovan wrote:
> > Hi Andrei,
> > 
> > * Emeltchenko Andrei <Andrei.Emeltchenko.news@gmail.com> [2011-09-07 17:05:14 +0300]:
> > 
> > > From: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
> > > 
> > > Calculate pdu length before creating I-frame. Otherwise if
> > > conn->mtu - (headers) < remote_mps we get fragmented packets in
> > > create_iframe_pdu function.
> > 
> > You might check the way we set the remote_mps, it seems you are not taking
> > that in account.
> 
> You are right, I was confused by magic "rfc.max_pdu_size =
> cpu_to_le16(chan->conn->mtu - 10)"
> 
> I will send new patch with fixes like the one below:
> 
> -               rfc.max_pdu_size    = cpu_to_le16(L2CAP_DEFAULT_MAX_PDU_SIZE);
> -               if (L2CAP_DEFAULT_MAX_PDU_SIZE > chan->conn->mtu - 10)
> -                       rfc.max_pdu_size = cpu_to_le16(chan->conn->mtu - 10);
> +
> +               rfc.max_pdu_size = cpu_to_le16(min_t(u16,
> +                                               L2CAP_DEFAULT_MAX_PDU_SIZE,
> +                                               chan->conn->mtu -
> +                                               L2CAP_EXTENDED_HDR_SIZE -
> +                                               L2CAP_SDULEN_SIZE -
> +                                               L2CAP_FCS_SIZE));

Then do this in two parts:

		size = min_t(...)
		rfc.max_pdu_size = cpu_to_le16(size);


	Gustavo