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Date: Tue, 30 Jul 2002 16:48:53 +0200
From: Abraham vd Merwe <abraham@2d3d.co.za>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linux Kernel Development <linux-kernel@vger.kernel.org>
Subject: Re: questions about network device drivers
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In-Reply-To: <1028044126.6726.35.camel@irongate.swansea.linux.org.uk>; from alan@lxorguk.ukuu.org.uk on Tue, Jul 30, 2002 at 16:48:46 +0100
Organization: 2d3D, Inc.
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Hi Alan!

> > hard_start_xmit() method
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> >=20
> > when should this function return 0 and when should it return 1 and in w=
hich
> > cases should it do netif_stop_queue() and/or free the dev_kfree_skb() ?
>=20
> 0 - OK
> 1 - I am busy, give me it later.
>=20
> If you return 1 be sure to netif_stop_queue. The netif_wake_queue will
> continue transmission

In both cases, should I free the sk_buff structure or only if I return 0?
Also, if I understand you correctly, I should _only_ call netif_stop_queue()
if the function fails to transmit the packet?

What about cases where the packet will always fail, e.g. the frame length is
bigger than what the device supports. I take it in those cases I should
return 0, but should I call netif_stop_queue() as well?

--=20

Regards
 Abraham

Here there be tygers.

__________________________________________________________
 Abraham vd Merwe - 2d3D, Inc.

 Device Driver Development, Outsourcing, Embedded Systems

  Cell: +27 82 565 4451         Snailmail:
   Tel: +27 21 761 7549            Block C, Aintree Park
   Fax: +27 21 761 7648            Doncaster Road
 Email: abraham@2d3d.co.za         Kenilworth, 7700
  Http: http://www.2d3d.com        South Africa


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