network driver issues

Jan Müller 217534 at
Mon Jan 16 21:19:46 UTC 2012

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.

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)

Many thanks for your help!


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