Date: Wed, 23 Jul 2008 14:21:47 -0700 (PDT)
Message-Id: <20080723.142147.61941255.davem@davemloft.net> (sfid-20080723_232152_705877_F97B0F78)
To: kaber@trash.net
Cc: francois.valenduc@tvcablenet.be, akpm@linux-foundation.org,
	bugme-daemon@bugzilla.kernel.org, linux-wireless@vger.kernel.org,
	linville@tuxdriver.com, netdev@vger.kernel.org,
	jussi.kivilinna@mbnet.fi
Subject: Re: [Bugme-new] [Bug 11144] New: dhcp doesn't work with iwl4965
From: David Miller <davem@davemloft.net>
In-Reply-To: <48875B8C.2090800@trash.net>
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	<4887555A.30605@trash.net>
	<48875B8C.2090800@trash.net>
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From: Patrick McHardy <kaber@trash.net>
Date: Wed, 23 Jul 2008 18:25:48 +0200

> We can't fit them into the cb together, I don't see a way to
> shrink ieee80211_tx_info.
> 
> Maybe one of the wireless folks can suggest something? Is it
> really necessary to pass the full struct ieee80211_tx_info
> through the qdisc layer, or could the struct be split? It
> needs to find a way to co-exist peacefully with qdiscs'
> skb->cb usage.

This is another area that got mangled up in the ->select_queue()
conversion of the WME bits, but in another aspect this problem
existed beforehand as well.

Specifically, when RX packets get requeued out to transmit in
the code in net/mac80211/rx.c that resends packets back out the
wireless device by setting a bit in the SKB CB then calling
dev_queue_xmit().

That's completely illegal :-)

There's a ton of stuff in that structure, I can't see how to
make it smaller either.  Maybe some bits only matter through
the layers of the TX mac80211 stack and thus can be passed
as parameters during such processing?