Re: [PATCH] mac80211: Limit number of pending skbs.

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2012-05-30 at 09:04 -0700, Ben Greear wrote:

> > There used to be bugs in this area in mac80211 and/or pktgen, and I
> > remember crashing my machine very trivially. I don't think that this is
> > still a problem though, but I haven't tried in a long time. FWIW, the
> > time-frame of this must've been ~2-3 years ago.
> 
> I think it's still broken..I've been carrying this patch for a year or two:
> 
>  From 5ad8e96ace28d798214ba6e203d143e6380e0605 Mon Sep 17 00:00:00 2001
> From: Ben Greear <greearb@candelatech.com>
> Date: Tue, 14 Jun 2011 11:01:50 -0700
> Subject: [PATCH 016/102] mac80211: Set up tx-queue-mapping in subif_start_xmit.
> 
> Otherwise, ath9k gets confused about which queue to use
> and spews a warning like this when driving traffic with
> pktgen.


> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index e05667c..1f026b5 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -2072,6 +2072,8 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
>   	} else
>   		memcpy(skb_push(skb, hdrlen), &hdr, hdrlen);
> 
> +	skb_set_queue_mapping(skb, ieee80211_select_queue(sdata, skb));

Looks like pktgen then doesn't care about the select_queue() call which
should be called before start_xmit

johannes