From: Ivo van Doorn <ivdoorn@gmail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: ieee80211_tx_status: headroom too small
Date: Sat, 31 Oct 2009 09:51:29 +0100
Cc: Nikolai ZHUBR <zhubr@mail.ru>, linux-wireless@vger.kernel.org
References: <1094614475.20091030230028@mail.ru> <7111590175.20091031005644@mail.ru> <1256967967.3555.71.camel@johannes.local>
In-Reply-To: <1256967967.3555.71.camel@johannes.local>
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On Saturday 31 October 2009, Johannes Berg wrote:
> On Sat, 2009-10-31 at 00:56 +0300, Nikolai ZHUBR wrote:
> > Friday, October 30, 2009, 11:59:01 PM, Johannes Berg wrote:
> > >>
> > >> ieee80211_tx_status: headroom too small
> > 
> > > What driver are you using?
> > 
> > Ah, sorry, forgot to mention. It is rt61pci (RaLink mini-PCI card)
> 
> Ok. I looked at the problem and it's a very odd problem -- mac80211
> should always reserve enough headroom in buffers it passes to the
> driver. Does rt61pci somehow realloc frames?

It does use skb_push. but will/should always stay within the limits
of rt2x00dev->hw->extra_tx_headroom. Although I just realize there
might be a situation where it needs to align the frame to a 4-byte boundary,
it could exceed that amount. :(

Ivo