Re: questions about network device drivers

From: Abraham vd Merwe (abraham@2d3d.co.za)
Date: Tue Jul 30 2002 - 09:48:53 EST

Hi Alan!

> > hard_start_xmit() method
> > ========================
> >
> > when should this function return 0 and when should it return 1 and in which
> > cases should it do netif_stop_queue() and/or free the dev_kfree_skb() ?
>
> 0 - OK
> 1 - I am busy, give me it later.
>
> 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? 

-- 

Regards
 Abraham

Here there be tygers.

__________________________________________________________
 Abraham vd Merwe - 2d3D, Inc.

 Device Driver Development, Outsourcing, Embedded Systems

  Cell: +27 82 565 4451         Snailmail:
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