Re: [PATCH] Bluetooth: Fix powering on with privacy and advertising

[Johan Hedberg <johan.hedberg@gmail.com>]

Hi Andrzej,

On Mon, Nov 16, 2015, Andrzej Kaczmarek wrote:
> On Fri, Nov 13, 2015 at 12:53 PM, Johan Hedberg <johan.hedberg@gmail.com> wrote:
> > Hi Andrzej,
> >
> > On Thu, Nov 12, 2015, Andrzej Kaczmarek wrote:
> >> In order to enable advertising with privacy enabled, SMP has to be
> >> registered in order to generate new RPA. During power on, it will be
> >> registered at the very end which is the reason why advertising is not
> >> enabled and it's not possible to enable it anymore due to mismatch
> >> between hci_dev settings and actual controller state.
> >>
> >> This fixes this problem by postponing advertising enable after SMP is
> >> registered in case of power on.
> >> ---
> >>  net/bluetooth/mgmt.c | 70 ++++++++++++++++++++++++++++++++++++++++------------
> >>  1 file changed, 54 insertions(+), 16 deletions(-)
> >
> > Instead of postponing advertising, did you consider simply moving
> > smp_register() earlier? Wouldn't it be possible to move it to
> > mgmt_powered() before powered_update_hci() is called?
> 
> smp_register() was already moved in 162a3bac8d0 so I assumed this is
> the right place for it and didn't want to move it again. But it seems
> it could be moved as you suggested, identity address is already know
> at that point. And this will make whole fix simple. I'll send v2
> later, unless Marcel disagrees with this proposal.

The place it was originally moved from (__hci_init) had no chance of
knowing the controller features that are needed to determine static
random vs public address. However, in mgmt_powered() the main HCI init
has already completed and this information should be available. There
are no HCI commands in powered_update_hci() that would provide
additional useful information for this decision.

Johan