netdev - Re: mac80211 truesize bugs

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Message-Id: <1209636494.4008.24.camel@johannes.berg>
Date:	Thu, 01 May 2008 12:08:14 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	David Miller <davem@...emloft.net>
Cc:	mb@...sch.de, netdev@...r.kernel.org,
	linux-wireless@...r.kernel.org
Subject: Re: mac80211 truesize bugs


> > Hmm. The disconnect between truesize and skb->len+sizeof(*skb) was
> > usually 17 or 19 bytes and sizeof(*rthdr) is only 11. On the other hand,
> > I don't see where the other bytes should be coming from. I'll give this
> > a try, thanks.

Even when I explicitly set truesize (rather than adjusting it as you
did) I still get a disconnect.

> Grrr, I bet it's coming from a combination of the
> skb_set_mac_header(skb, 0); call done by mac80211 and the skb_push()
> calls in net/packet/af_packet.c
> 
> davem@...set:~/src/GIT/net-2.6$ egrep skb_push net/packet/af_packet.c
> 	skb_push(skb, skb->data - skb_mac_header(skb));
> 			skb_push(skb, skb->data - skb_mac_header(skb));
> 			skb_push(skb, skb->data - skb_mac_header(skb));

But mac80211 does set_mac_header(0) so this should just push zero bytes,
no?

johannes

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