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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Wed, 19 Aug 2020 11:25:34 -0700
Message-ID: <CABBYNZ+F=-YsZoL4B9=XQvHSs9wU=0W3iqbYn4s65JMAJAmAKw@mail.gmail.com>
Subject: Re: [PATCH v1 2/2] Bluetooth: sco: expose WBS packet length in socket option
To:     =?UTF-8?Q?Pali_Roh=C3=A1r?= <pali@kernel.org>
Cc:     Joseph Hwang <josephsih@chromium.org>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        Marcel Holtmann <marcel@holtmann.org>,
        Joseph Hwang <josephsih@google.com>,
        ChromeOS Bluetooth Upstreaming 
        <chromeos-bluetooth-upstreaming@chromium.org>,
        Alain Michaud <alainm@chromium.org>,
        Abhishek Pandit-Subedi <abhishekpandit@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>
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On Wed, Aug 19, 2020 at 11:23 AM Pali Roh=C3=A1r <pali@kernel.org> wrote:
>
> 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 Roh=C3=A1r <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.or=
g> 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/blue=
tooth/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 =3D hdev->sco_pkt_len;
> > > > > +
> > > > >  done:
> > > > >         hci_dev_unlock(hdev);
> > > > >         hci_dev_put(hdev);
> > > > > @@ -1001,6 +1004,11 @@ static int sco_sock_getsockopt(struct sock=
et *sock, int level, int optname,
> > > > >                         err =3D -EFAULT;
> > > > >                 break;
> > > > >
> > > > > +       case BT_SCO_PKT_LEN:
> > > > > +               if (put_user(sco_pi(sk)->pkt_len, (u32 __user *)o=
ptval))
> > > > > +                       err =3D -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.

Yep, luckily we can do this here because SCO MTU is symmetric.

> > >
> > > > >         default:
> > > > >                 err =3D -ENOPROTOOPT;
> > > > >                 break;
> > > > > --
> > > > > 2.28.0.236.gb10cc79966-goog
> > > > >
> > > >
> > > >
> > > > --
> > > > Luiz Augusto von Dentz
> >
> >
> >
> > --
> > Luiz Augusto von Dentz


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Luiz Augusto von Dentz