netdev - Re: Wireless networking without CONFIG

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Date:	Tue, 5 Jun 2012 07:50:54 +0200
From:	Sedat Dilek <sedat.dilek@...glemail.com>
To:	Linus Torvalds <linus971@...il.com>
Cc:	"John W. Linville" <linville@...driver.com>,
	Johannes Berg <johannes@...solutions.net>,
	"David S. Miller" <davem@...emloft.net>,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: Wireless networking without CONFIG_PM..

On Tue, Jun 5, 2012 at 5:09 AM, Linus Torvalds <linus971@...il.com> wrote:
> I wonder if anybody has really ever tested that? Because I think it's broken..
>
> In particular, I made the mistake of not enabling CONFIG_PM on a new
> laptop, and it caused some *seriously* nasty-to-debug problems. The
> mac80211 code goes crazy, that upsets the wireless driver, and then
> the wrieless driver in question had a nasty bug where it would
> double-release its firmware, which then caused vmalloc corruption and
> all kinds of really odd recursive panics etc.
>
> And as far as I can tell, the root cause of the problem is a bad
> choice in net/mac80211/main.c:
>
>  int ieee80211_register_hw(struct ieee80211_hw *hw)
>  {
>  ...
>        if ((hw->wiphy->wowlan.flags || hw->wiphy->wowlan.n_patterns)
>  #ifdef CONFIG_PM
>            && (!local->ops->suspend || !local->ops->resume)
>  #endif
>            )
>                return -EINVAL;
>
> which means that if the wiphy says it supports wake-on-wireless lan,
> and CONFIG_PM isn't enabled, we'll return -EINVAL and will refuse to
> do any wireless at all.
>
> It's that a bit extreme? Or outright stupid? What is the advantage of
> saying that "if you don't have CONFIG_PM enabled, we'll just refuse to
> register any hardware that talks about it's wake-on-wireless
> patterns"?
>
> Maybe there is some reason for that return -EINVAL, but I don't think
> it makes sense with that particular placement of #ifdef CONFIG_PM.
> Maybe if the #ifdef was around the whole test? Or maybe it should just
> be removed.
>
> Or am I missing some big reason for why it makes sense to do that? Hmm?
>
> I'll make a separate bug-report email to the intel iwlwifi people
> about their absolutely horribly broken error handling which then made
> it such a disaster, but I thought I'd bring the generic mac80211 issue
> up. I don't think there are a lot of drivers that do the whole wowlan
> thing, and obviously most people use wireless on laptops where you
> want CONFIG_PM anyway, so it probably hasn't triggered very much.
>
>                  Linus

Sounds like you have hit...

"[PATCH 3.5 v2] iwlwifi: disable WoWLAN if !CONFIG_PM_SLEEP"
http://www.spinics.net/lists/linux-wireless/msg91308.html

- Sedat -
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