Subject: Re: ath5k oops (recent regression, I think)
From: Johannes Berg <johannes@sipsolutions.net>
To: "Luis R. Rodriguez" <mcgrof@gmail.com>
Cc: bruno randolf <bruno@thinktube.com>,
	Nick Kossifidis <mickflemm@gmail.com>,
	Andrew Lutomirski <luto@myrealbox.com>,
	linux-wireless@vger.kernel.org
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	 <200712251804.13693.bruno@thinktube.com>
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	 <43e72e890801031602q38a8f57fv3ba56a0f44e7e2c6@mail.gmail.com>
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Date: Fri, 04 Jan 2008 01:34:14 +0100
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> We use ieee80211_generic_frame_duration() to compute what we believe
> is the ACK timeout and set it on the rate duration registers, and we
> need this value set during reset, as we up the interface. The *real*
> problem here is we need mac80211 to provide an exported routine which
> drivers can use even if they don't have an up'd interface yet IMHO.
> This can be easily fixed by making ieee80211_generic_frame_duration()
> not rely on sdata and letting the user pass manually if short preamble
> is desired in the calculation as an arg. I have to go now but will try
> to address this as soon as I have time unless someone beats me.

That'd be wrong as well because w/o a virtual interface you can't be
associated and hence you have no way of knowing whether the frame
duration should be for short preamble or not.

Besides, the old behaviour was to return 0 from the frame_duration()
function when an invalid interface ID was passed which would always
happen in this function.

I think you need to rethink what this piece of code is trying to
accomplish and fix it accordingly.

johannes

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