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From: Ben Hutchings <bhutchings-s/n/eUQHGBpZroRs9YW3xA@public.gmane.org>
To: Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
Cc: <netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	<linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: changing dev->needed_headroom/needed_tailroom?
Date: Fri, 2 Aug 2013 10:55:58 +0200	[thread overview]
Message-ID: <1375433758.24371.20.camel@deadeye.wl.decadent.org.uk> (raw)
In-Reply-To: <1374850210.8248.59.camel-8Nb76shvtaUJvtFkdXX2HixXY32XiHfO@public.gmane.org>

On Fri, 2013-07-26 at 16:50 +0200, Johannes Berg wrote:
> Does it seem reasonable to change dev->needed_headroom and
> dev->needed_tailroom on the fly?
> 
> We currently set needed_headroom to the max of what we need, but we
> could do better like making it depend on the interface type (e.g. only
> asking for mesh space on mesh interfaces). This would be done only when
> the interface isn't connected, I can't promise it would be down but the
> carrier would be off.
[...]

I don't think this is safe when the interface is running (even if
carrier is off).  Some functions may read dev->needed_headroom twice and
rely on getting the same value each time.

Also, stacked devices would need to adjust their own needed_headroom
accordingly.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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  parent reply	other threads:[~2013-08-02  8:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-26 14:50 changing dev->needed_headroom/needed_tailroom? Johannes Berg
     [not found] ` <1374850210.8248.59.camel-8Nb76shvtaUJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2013-08-02  8:55   ` Ben Hutchings [this message]
     [not found]     ` <1375433758.24371.20.camel-nDn/Rdv9kqW9Jme8/bJn5UCKIB8iOfG2tUK59QYPAWc@public.gmane.org>
2013-08-02 13:11       ` Eric Dumazet
2013-08-05 14:00         ` Johannes Berg
     [not found]           ` <1375711240.8120.11.camel-8Nb76shvtaUJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2013-08-20 10:00             ` Florian Fainelli
     [not found]               ` <CAGVrzcaGV6AqLTAxpM6zMv7_C-LNxp-WNg+J47d7a9S+Ca1bDw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-08-20 16:20                 ` Stephen Hemminger
2013-08-20 16:24                   ` Johannes Berg
2013-08-20 16:29                     ` Stephen Hemminger

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