return values for hard_start_xmit and dev_queue_xmit

return values for hard_start_xmit and dev_queue_xmit

[Ben Greear]

While trying to get pktgen to effectively use VLANs to send traffic,
I noticed that the vlan code always returns 0 from it's hard_start_xmit
method.  Since it calls dev_queue_xmit inside that method, I tried
returning the value that dev_queue_xmit returns.  It seems that the
return values have different meanings because this causes crashes due
to freeing skbs when I shouldn't be...

The dev_queue_xmit method is fairly well documented in dev.c, but
there are zero comments in the netdevice.h file to explain what the
acceptable return values for hard_start_xmit are.

Does anyone know if there is a definative guide to the return values
for hard_start_xmit?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: return values for hard_start_xmit and dev_queue_xmit

[Ben Greear]

Ben Greear wrote:

> The dev_queue_xmit method is fairly well documented in dev.c, but
> there are zero comments in the netdevice.h file to explain what the
> acceptable return values for hard_start_xmit are.

Actually, looks like I'm wrong here.  The comments in dev.c say that
error codes are < 0, but in fact, this can easily return NET_XMIT_DROP
which is a positive value (1).

Maybe the truth is that any non-zero return value from dev_queue_xmit
is an error?

Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com