Re: [PATCH v5 2/3] mac80211: implement chanctx reservation

[Luca Coelho <lrothc@gmail.com>]

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.