netdev - handing cloned frames to netif

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Date:	Fri, 11 Jan 2008 02:17:26 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	netdev <netdev@...r.kernel.org>
Cc:	Ron Rindjunsky <ron.rindjunsky@...el.com>,
	linux-wireless <linux-wireless@...r.kernel.org>
Subject: handing cloned frames to netif_rx()?

In 802.11n, there is a case where multiple data frames are received
aggregated into a single frame (A-MSDU).

Currently, we copy each of these frames out into their own skb, but
because of the alignment with that etc. I started to think that we could
simply pass up a clone of the original skb with start/length adjusted
properly so that it windows only the contained packet.

The buffer would be shared but the data within the original window
(starting with the 802.3 header) could even be written to, it won't be
needed again by mac80211 once it's handed off to netif_rx(). The skb
will obviously have lots of head- and tailroom but that space would be
part of other packets.

Is it ok to do this? Will something freak out if we pass a cloned skb to
netif_rx()?

johannes

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