network driver issues

Greg KH greg at
Tue Jan 17 00:17:02 UTC 2012

On Mon, Jan 16, 2012 at 10:19:46PM +0100, Jan Müller wrote:
> Dear all,
> I try adapting a network driver (net/ethernet/xilinx/ll_temac) for
> my needs, but I'm not sure I understand the issues involved.

What are your needs?  Specifically please.  And why are you modifying
this specific one?

> Maybe someone of you could point me in the right directions?
> For instance, does the *skb structure passed to the start_xmit
> function has to be freed by the network driver in any case? I.e. not
> calling dev_kfree_skb(skb) anywhere in the driver is a bug?
> I'm a bit confused about the need for locking tx-buffers (for
> SG-dma). Somewhere (in the comments for another driver) I've read
> the calls to start_xmit are serialised anyway? And then clearing the
> dma tx buffer in the tx_irq should be fine because it should not get
> interrupted?
> Could you maybe recommend a simple "role model" net/ethernet/ driver
> I should have a look at? One which implements a locked tx buffer (in
> case you think that's needed at all)

Have you looked at the network skeleton driver?


greg k-h

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