Re: [PATCH v1 2/2] Bluetooth: sco: expose WBS packet length in socket option

["Pali Rohár" <pali@kernel.org>]

On Wednesday 19 August 2020 11:21:00 Luiz Augusto von Dentz wrote:
> Hi Pali,
> 
> On Wed, Aug 19, 2020 at 7:37 AM Pali Rohár <pali@kernel.org> wrote:
> >
> > On Friday 14 August 2020 12:56:05 Luiz Augusto von Dentz wrote:
> > > Hi Joseph,
> > >
> > > On Thu, Aug 13, 2020 at 1:42 AM Joseph Hwang <josephsih@chromium.org> wrote:
> > > >
> > > > It is desirable to expose the wideband speech packet length via
> > > > a socket option to the user space so that the user space can set
> > > > the value correctly in configuring the sco connection.
> > > >
> > > > Reviewed-by: Alain Michaud <alainm@chromium.org>
> > > > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > > > Signed-off-by: Joseph Hwang <josephsih@chromium.org>
> > > > ---
> > > >
> > > >  include/net/bluetooth/bluetooth.h | 2 ++
> > > >  net/bluetooth/sco.c               | 8 ++++++++
> > > >  2 files changed, 10 insertions(+)
> > > >
> > > > diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> > > > index 9125effbf4483d..922cc03143def4 100644
> > > > --- a/include/net/bluetooth/bluetooth.h
> > > > +++ b/include/net/bluetooth/bluetooth.h
> > > > @@ -153,6 +153,8 @@ struct bt_voice {
> > > >
> > > >  #define BT_SCM_PKT_STATUS      0x03
> > > >
> > > > +#define BT_SCO_PKT_LEN         17
> > > > +
> > > >  __printf(1, 2)
> > > >  void bt_info(const char *fmt, ...);
> > > >  __printf(1, 2)
> > > > diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
> > > > index dcf7f96ff417e6..97e4e7c7b8cf62 100644
> > > > --- a/net/bluetooth/sco.c
> > > > +++ b/net/bluetooth/sco.c
> > > > @@ -67,6 +67,7 @@ struct sco_pinfo {
> > > >         __u32           flags;
> > > >         __u16           setting;
> > > >         __u8            cmsg_mask;
> > > > +       __u32           pkt_len;
> > > >         struct sco_conn *conn;
> > > >  };
> > > >
> > > > @@ -267,6 +268,8 @@ static int sco_connect(struct sock *sk)
> > > >                 sco_sock_set_timer(sk, sk->sk_sndtimeo);
> > > >         }
> > > >
> > > > +       sco_pi(sk)->pkt_len = hdev->sco_pkt_len;
> > > > +
> > > >  done:
> > > >         hci_dev_unlock(hdev);
> > > >         hci_dev_put(hdev);
> > > > @@ -1001,6 +1004,11 @@ static int sco_sock_getsockopt(struct socket *sock, int level, int optname,
> > > >                         err = -EFAULT;
> > > >                 break;
> > > >
> > > > +       case BT_SCO_PKT_LEN:
> > > > +               if (put_user(sco_pi(sk)->pkt_len, (u32 __user *)optval))
> > > > +                       err = -EFAULT;
> > > > +               break;
> > >
> > > Couldn't we expose this via BT_SNDMTU/BT_RCVMTU?
> >
> > Hello!
> >
> > There is already SCO_OPTIONS sock option, uses struct sco_options and
> > contains 'mtu' member.
> >
> > I think that instead of adding new sock option, existing SCO_OPTIONS
> > option should be used.
> 
> We are moving away from type specific options to so options like
> BT_SNDMTU/BT_RCVMTU should be supported in all socket types.

Yes, this make sense.

But I guess that SCO_OPTIONS should be provided for backward
compatibility as it is already used by lot of userspace applications.

So for me it looks like that BT_SNDMTU/BT_RCVMTU should return same
value as SCO_OPTIONS.

> >
> > > >         default:
> > > >                 err = -ENOPROTOOPT;
> > > >                 break;
> > > > --
> > > > 2.28.0.236.gb10cc79966-goog
> > > >
> > >
> > >
> > > --
> > > Luiz Augusto von Dentz
> 
> 
> 
> -- 
> Luiz Augusto von Dentz