Subject: Re: [RFC 1/2] wireless: add ieee80211_asmdu_to_8023s
From: Johannes Berg <johannes@sipsolutions.net>
To: Zhu Yi <yi.zhu@intel.com>
Cc: "linville@tuxdriver.com" <linville@tuxdriver.com>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
In-Reply-To: <1259314217.12157.3.camel@debian>
References: <1259215413-16753-1-git-send-email-yi.zhu@intel.com>
	 <1259229943.32372.50.camel@johannes.local>
	 <1259290376.13126.219.camel@debian>
	 <1259313653.5428.5.camel@johannes.local>  <1259314217.12157.3.camel@debian>
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Date: Fri, 27 Nov 2009 10:33:27 +0100
Message-ID: <1259314407.5428.8.camel@johannes.local>
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On Fri, 2009-11-27 at 17:30 +0800, Zhu Yi wrote:
> On Fri, 2009-11-27 at 17:20 +0800, Johannes Berg wrote:
> > Is it? I don't think so. Many drivers go up beyond that as far as I
> > know. Then some do different things like putting it in a different DMA
> > block.
> >=20
> > > While for those drivers really need a bigger
> > > extra headroom and support Rx aggregation, this probably means
> > > ieee80211_skb_resize. But the resize should always happen for every
> > > packet from the IP stack, right?
> >=20
> > No, davem and I optimised that away a long time ago via using
> > netdev->needed_headroom and netdev->needed_tailroom. It even works for
> > bridges and their slave devices, iirc.=20
>=20
> I missed this. Will check it. If so, I'll add another parameter to pass
> the extra hw tx headroom to ieee80211_asmdu_to_8023s.

The thing is that I'm not even sure if we can possibly forward a frame
after this deaggregation. I'll poke at the code.

johannes

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