From: Ivo van Doorn <ivdoorn@gmail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Nikolai ZHUBR <zhubr@mail.ru>, linux-wireless@vger.kernel.org
Subject: Re: ieee80211_tx_status: headroom too small
Date: Sat, 31 Oct 2009 09:59:42 +0100 [thread overview]
Message-ID: <200910310959.43260.IvDoorn@gmail.com> (raw)
In-Reply-To: <1256979370.3555.91.camel@johannes.local>
On Saturday 31 October 2009, Johannes Berg wrote:
> On Sat, 2009-10-31 at 09:51 +0100, Ivo van Doorn wrote:
>
> > > 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. :(
>
> extra_tx_headroom is set to max_t(driver, mac80211) so that there's
> always some headroom. This doesn't take into account alignment though.
> Should we simply add 2 to that value?
4 actually, wasn't there some cases where the header could have an odd
number of bytes and would require 3 bytes for alignment?
Ivo
next prev parent reply other threads:[~2009-10-31 9:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-30 20:00 ieee80211_tx_status: headroom too small Nikolai ZHUBR
2009-10-30 20:03 ` Luis R. Rodriguez
2009-10-30 20:49 ` Re[2]: " Nikolai ZHUBR
2009-10-30 20:59 ` Johannes Berg
2009-10-30 21:56 ` Re[2]: " Nikolai ZHUBR
2009-10-31 5:46 ` Johannes Berg
2009-10-31 8:51 ` Ivo van Doorn
2009-10-31 8:56 ` Johannes Berg
2009-10-31 8:59 ` Ivo van Doorn [this message]
2009-10-31 9:25 ` Johannes Berg
2009-10-31 9:30 ` Ivo van Doorn
2009-10-31 9:34 ` Johannes Berg
2009-10-31 9:44 ` Ivo van Doorn
2009-10-31 10:03 ` Johannes Berg
2009-10-31 10:17 ` Ivo van Doorn
2009-10-31 10:23 ` Johannes Berg
2009-10-31 10:33 ` Ivo van Doorn
2009-10-31 14:24 ` Re[2]: " Nikolai ZHUBR
2009-10-31 15:35 ` Johannes Berg
2009-10-31 17:42 ` Re[4]: " Nikolai ZHUBR
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