Message-ID: <1422623446.1919.20.camel@sipsolutions.net> (sfid-20150130_141053_531619_40568736)
Subject: Re: [PATCH v2 2/7] ath10k: implement chanctx API
From: Johannes Berg <johannes@sipsolutions.net>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: "ath10k@lists.infradead.org" <ath10k@lists.infradead.org>,
	linux-wireless <linux-wireless@vger.kernel.org>
Date: Fri, 30 Jan 2015 14:10:46 +0100
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On Fri, 2015-01-30 at 14:06 +0100, Michal Kazior wrote:

> I'm a bit reluctant to freely use mac80211 owned structures out of
> mac80211_ops callback context, i.e. from a tasklet fearing
> inconsistencies. Or am I worrying unnecessarily? If so I guess I'll
> redo this and use mac80211's structures directly :-)

Yeah that's a concern, we were just looking at something similar.
However, I think at least with channel contexts you should be fine since
mac80211 never really modifies them much, except for the width and # of
chains needed?

We've recently seen a similar issue with vif->bss_conf, and I'm
considering making that an RCU-protected pointer rather than the
embedded sub-struct, that way mac80211 can replace it atomically when
needed. I've yet to see if that's practical though.

johannes