Hi Johannes,
After thinking about this more:
On Fri, 2019-10-04 at 09:25 -0700, James Prestwood wrote:
> On Fri, 2019-10-04 at 13:56 +0200, Johannes Berg wrote:
> > Hi,
> >
> > I was tempted to apply this (sans the feature advertisement part
> > that
> > I
> > don't think should be in nl80211), but:
> >
> > >
> > > Signed-off-by: James Prestwood <prestwoj@xxxxxxxxx>
> >
> > Please add a commit log.
> >
> > > +static int ieee80211_can_live_addr_change(struct
> > > ieee80211_sub_if_data *sdata)
> > > +{
> > > + if (netif_carrier_ok(sdata->dev))
> > > + return -EBUSY;
> > > +
> > > + switch (sdata->vif.type) {
> > > + case NL80211_IFTYPE_AP:
> > > + case NL80211_IFTYPE_P2P_GO:
> > > + case NL80211_IFTYPE_AP_VLAN:
> > > + case NL80211_IFTYPE_WDS:
> > > + case NL80211_IFTYPE_MESH_POINT:
> > > + case NL80211_IFTYPE_MONITOR:
> > > + case NL80211_IFTYPE_OCB:
> > > + /* No further checking required, when started or UP
> > > these
> > > + * interface types set carrier
> > > + */
> > > + break;
> > > + case NL80211_IFTYPE_ADHOC:
> > > + if (sdata->u.ibss.ssid_len != 0)
> > > + return -EBUSY;
> >
> > Can you please document why this is there? Maybe all of the
> > conditions,
> > for that matter.
> >
> > I'm not even entirely sure it _is_ needed - if we've still not
> > created
> > the IBSS but are scanning for it or trying to merge the MAC address
> > won't really matter yet? Probably?
>
> I guess its just paranoia, rather be safe than sorry. I can take this
> out, but is "Probably?" a good reason? ;)
>
> >
> > > + break;
> > > + case NL80211_IFTYPE_STATION:
> > > + case NL80211_IFTYPE_P2P_CLIENT:
> > > + if (!list_empty(&sdata->local->roc_list) ||
> > > + !sdata->local->scanning)
> > > + return -EBUSY;
> >
> > AP, mesh and other interfaces *can* scan, so that test should be
> > pulled
> > out to be generic - but then in fact all of them should probably be
> > generic - ROC maybe can't be done on other interfaces yet, but
> > unless
> > you're going to check *which* interface is actually doing the ROC,
> > you
> > should just make that a generic check that applies to all
> > interfaces.
>
> Ok so no switch statement, simply just check that we aren't
> offchannel
> or scanning. I guess this would then cover the IBSS case too.
>
> >
> > If you do care about this being more granular then you should check
> > *which* interface is scanning, and then you can still switch the
> > MAC
> > address for *other* interfaces - but I'd still argue it should be
> > independent of interface type.
So yes these can scan, but this should be covered by the
netif_carrier_ok check which is done first. We can just remove the
switch entirely, but the roc_list/scanning check only matters for
station/p2p_client so checking for the other interface types is kinda
pointless and redundant.
Also I am not sure what you mean by *which* interface. This function is
called on a single interface, so checking what other interfaces are
doing seems strange...
>
> >
> > And, I'm confused, but isn't the polarity of the scanning check
> > wrong?
>
> Ah yeah, after you pointed that out I realized 'scanning' is a bit
> field. I should be doing:
>
> test_bit(SCAN_HW_SCANNING, &sdata->local->scanning)
>
> Feel free the merge this, but I haven t had a chance yet to look into
> adding a flag to RTNL (based on what you said in your previous
> email).
> Without some way of telling userspace this is supported, its kinda
> useless IMO.
>
> Either way I'll send another patch with these things addressed.
>
> Thanks,
> James
>
> >
> > johannes
> >
>
>
