Re: Is skb->queue_mapping valid for received packets?

On Mon, Jun 13, 2011 at 07:06:53PM -0700, Ben Greear wrote:

On 06/13/2011 06:59 PM, Ben Greear wrote:

quoted

Anyone know if skb->queue_mapping is set for incoming packets, ie to
notify which queue they came in on? I can't find it set anywhere,
and it appears it is sometimes set to 1 when it should be 0 in
my system.

Maybe it's never actually set, and I'm just reading some stale
data?

Bleh, found it the second I posted.

Seems it's skb_record_rx_queue(), and funny enough, it seems to add +1,
so if you are trying to bridge pkts from eth0 to eth1 on the same queues,
looks like you need to subtract one on xmit before finding the txqueue.

Or something like that.

Just saw your response after I replied. :-)

The queue_mapping storage is a bit odd, but it generally works.  The
value stored in queue_mapping should be decremented properly in
dev_pick_tx and it should go out of your card with a tx queue that
matches the rx queue.

There were some issues discovered and fixed with bonding last week
related to queue_mapping and I would not be surprised if another stacked
interface like bridging had an issue.