Message-ID: <1394442523.18265.9.camel@dubbel> (sfid-20140310_100855_592590_8AE34AD5)
Subject: Re: [PATCH v5 2/3] mac80211: implement chanctx reservation
From: Luca Coelho <lrothc@gmail.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	Johannes Berg <johannes@sipsolutions.net>,
	sw@simonwunderlich.de,
	"Otcheretianski, Andrei" <andrei.otcheretianski@intel.com>
Date: Mon, 10 Mar 2014 11:08:43 +0200
In-Reply-To: <CA+BoTQmOPZGLt0Bv+YSZcXVif65G6+tRP0sbhcJEvz65FjABRg@mail.gmail.com>
References: <1394017904-4012-1-git-send-email-luca@coelho.fi>
	 <1394017904-4012-3-git-send-email-luca@coelho.fi>
	 <CA+BoTQkb95xGNtVUxvn_u==P6fuy-h0iNAp8pGEcq8m0ZUm-7A@mail.gmail.com>
	 <1394174912.4192.9.camel@dubbel>
	 <CA+BoTQmOPZGLt0Bv+YSZcXVif65G6+tRP0sbhcJEvz65FjABRg@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Sender: linux-wireless-owner@vger.kernel.org

On Mon, 2014-03-10 at 08:03 +0100, Michal Kazior wrote:
> On 7 March 2014 07:48, Luca Coelho <luca@coelho.fi> wrote:
> > On Wed, 2014-03-05 at 13:04 +0100, Michal Kazior wrote:
> >> On 5 March 2014 12:11, Luca Coelho <luca@coelho.fi> wrote:
> >>
> >> [...]
> >>
> >> > +       /* unref our reservation before assigning */
> >> > +       ctx->refcount--;
> >> > +       sdata->reserved_chanctx = NULL;
> >> > +       ret = ieee80211_assign_vif_chanctx(sdata, ctx);
> >> > +       if (ret) {
> >> > +               /* if assign fails refcount stays the same */
> >> > +               if (ctx->refcount == 0)
> >> > +                       ieee80211_free_chanctx(local, ctx);
> >> > +               goto out_wake;
> >> > +       }
> >>
> >> This actually won't work if there are AP VLANs (I noticed that yesterday).
> >>
> >> You can't call ieee80211_vif_copy_chanctx_to_vlans() here due to
> >> current locking requirements. I have a patch for that though ;-) I'll
> >> send it soon.
> >
> > How is this related to this patch?
> >
> > Anyway, good to know that you have fixed it. :)
> 
> If you re-assign a chanctx of an AP that has VLANs you leave VLANs
> with the old chanctx pointer. Those pointers should be updated or else
> you'll end up dereferencing an invalid pointer.

I see.  So, I need to call ieee80211_vif_copy_chanctx_to_vlans() here,
but to do that I need your patch that allows it to be called without the
RTNL.

So, now this series will depend on that patch, I'll talk to Johannes.

--
Luca.