Received-SPF: pass (google.com: domain of linux-bluetooth-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200603145205.125167-1-alainm@chromium.org> <CABBYNZ+Os=u4=r+mSq+C9nRyN=PC6Yk7GNTGhto_2-TBmHxdRQ@mail.gmail.com>
 <CALWDO_V4Gy+3m1uznc3ZeGugpJqV94WOkvdZE1hs8izKU1q7=w@mail.gmail.com>
In-Reply-To: <CALWDO_V4Gy+3m1uznc3ZeGugpJqV94WOkvdZE1hs8izKU1q7=w@mail.gmail.com>
From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Wed, 3 Jun 2020 17:56:08 -0700
Message-ID: <CABBYNZ+UmGfM5CqZKV71-e1bRtrLZ76a8B_1bh+DANf=2wTrdw@mail.gmail.com>
Subject: Re: [PATCH v3] sco:Add support for BT_PKT_STATUS CMSG data
To:     Alain Michaud <alainmichaud@google.com>
Cc:     Alain Michaud <alainm@chromium.org>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Alain,

On Wed, Jun 3, 2020 at 5:34 PM Alain Michaud <alainmichaud@google.com> wrote:
>
> Hi Luiz
>
> On Wed, Jun 3, 2020 at 5:15 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Alain, Marcel,
> >
> > On Wed, Jun 3, 2020 at 7:56 AM Alain Michaud <alainm@chromium.org> wrote:
> > >
> > > This change adds support for reporting the BT_PKT_STATUS to the socket
> > > CMSG data to allow the implementation of a packet loss correction on
> > > erronous data received on the SCO socket.
> > >
> > > The patch was partially developed by Marcel Holtmann and validated by
> > > Hsin-yu Chao
> > >
> > > Signed-off-by: Alain Michaud <alainm@chromium.org>
> > >
> > > ---
> > >
> > >  include/net/bluetooth/bluetooth.h |  8 +++++++
> > >  include/net/bluetooth/sco.h       |  3 +++
> > >  net/bluetooth/af_bluetooth.c      |  3 +++
> > >  net/bluetooth/hci_core.c          |  1 +
> > >  net/bluetooth/sco.c               | 35 +++++++++++++++++++++++++++++++
> > >  5 files changed, 50 insertions(+)
> > >
> > > diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> > > index 3fa7b1e3c5d9..85e6c5754448 100644
> > > --- a/include/net/bluetooth/bluetooth.h
> > > +++ b/include/net/bluetooth/bluetooth.h
> > > @@ -147,6 +147,8 @@ struct bt_voice {
> > >  #define BT_MODE_LE_FLOWCTL     0x03
> > >  #define BT_MODE_EXT_FLOWCTL    0x04
> > >
> > > +#define BT_PKT_STATUS          16
> > > +
> > >  __printf(1, 2)
> > >  void bt_info(const char *fmt, ...);
> > >  __printf(1, 2)
> > > @@ -275,6 +277,7 @@ struct bt_sock {
> > >         struct sock *parent;
> > >         unsigned long flags;
> > >         void (*skb_msg_name)(struct sk_buff *, void *, int *);
> > > +       void (*skb_put_cmsg)(struct sk_buff *, struct msghdr *, struct sock *);
> > >  };
> > >
> > >  enum {
> > > @@ -324,6 +327,10 @@ struct l2cap_ctrl {
> > >         struct l2cap_chan *chan;
> > >  };
> > >
> > > +struct sco_ctrl {
> > > +       u8      pkt_status;
> > > +};
> > > +
> > >  struct hci_dev;
> > >
> > >  typedef void (*hci_req_complete_t)(struct hci_dev *hdev, u8 status, u16 opcode);
> > > @@ -350,6 +357,7 @@ struct bt_skb_cb {
> > >         u8 incoming:1;
> > >         union {
> > >                 struct l2cap_ctrl l2cap;
> > > +               struct sco_ctrl sco;
> > >                 struct hci_ctrl hci;
> > >         };
> > >  };
> > > diff --git a/include/net/bluetooth/sco.h b/include/net/bluetooth/sco.h
> > > index f40ddb4264fc..7f0d7bdc53f6 100644
> > > --- a/include/net/bluetooth/sco.h
> > > +++ b/include/net/bluetooth/sco.h
> > > @@ -46,4 +46,7 @@ struct sco_conninfo {
> > >         __u8  dev_class[3];
> > >  };
> > >
> > > +/* CMSG flags */
> > > +#define SCO_CMSG_PKT_STATUS    0x0001
> > > +
> >
> > I wonder if we can make this generic since ISO also has similar status
> > of received packets so I was hoping I could reuse the same flag to
> > indicate we want packet status to be transmitted with cmsg. Maybe have
> > it as BT_CMSG_PKT_STATUS?
> I think CMSG flags will be different based on the socket types.  I
> agree it's possible some will be shared between SCO and ISO, but I
> would hesitate to make this generic to BT since it doesn't apply to
> all BT sockets.  This also isn't exposed to external components
> either, it's sort of a SCO internal implementation detail more than
> anything.  ISO could have something similar and likely other flags...

I was thinking that the flag could be the same just the content is
different based on the socket type that way there is not even a chance
of using a flag that is only suppose to work with certain socket type,
BT_PKT_STATUS naming itself since to be generic enough so I wonder if
the change of namespace does really make sense given that I could
enable that on ISO socket but then I would have to add a separate flag
for it? It is probably not a big deal we have been moving away from
protocol specific options ever since we started using  BT_ namespace
for socket options.

>
> >
> > >  #endif /* __SCO_H */
> > > diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
> > > index 3fd124927d4d..d0abea8d08cc 100644
> > > --- a/net/bluetooth/af_bluetooth.c
> > > +++ b/net/bluetooth/af_bluetooth.c
> > > @@ -286,6 +286,9 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> > >                 if (msg->msg_name && bt_sk(sk)->skb_msg_name)
> > >                         bt_sk(sk)->skb_msg_name(skb, msg->msg_name,
> > >                                                 &msg->msg_namelen);
> > > +
> > > +               if (bt_sk(sk)->skb_put_cmsg)
> > > +                       bt_sk(sk)->skb_put_cmsg(skb, msg, sk);
> > >         }
> > >
> > >         skb_free_datagram(sk, skb);
> > > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > > index 51d399273276..7b5e46198d99 100644
> > > --- a/net/bluetooth/hci_core.c
> > > +++ b/net/bluetooth/hci_core.c
> > > @@ -4549,6 +4549,7 @@ static void hci_scodata_packet(struct hci_dev *hdev, struct sk_buff *skb)
> > >
> > >         if (conn) {
> > >                 /* Send to upper protocol */
> > > +               bt_cb(skb)->sco.pkt_status = flags & 0x03;
> > >                 sco_recv_scodata(conn, skb);
> > >                 return;
> > >         } else {
> > > diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
> > > index c8c3d38cdc7b..f6b54853e547 100644
> > > --- a/net/bluetooth/sco.c
> > > +++ b/net/bluetooth/sco.c
> > > @@ -66,6 +66,7 @@ struct sco_pinfo {
> > >         bdaddr_t        dst;
> > >         __u32           flags;
> > >         __u16           setting;
> > > +       __u32           cmsg_mask;
> > >         struct sco_conn *conn;
> > >  };
> > >
> > > @@ -449,6 +450,15 @@ static void sco_sock_close(struct sock *sk)
> > >         sco_sock_kill(sk);
> > >  }
> > >
> > > +static void sco_skb_put_cmsg(struct sk_buff *skb, struct msghdr *msg,
> > > +                            struct sock *sk)
> > > +{
> > > +       if (sco_pi(sk)->cmsg_mask & SCO_CMSG_PKT_STATUS)
> > > +               put_cmsg(msg, SOL_BLUETOOTH, BT_PKT_STATUS,
> > > +                        sizeof(bt_cb(skb)->sco.pkt_status),
> > > +                        &bt_cb(skb)->sco.pkt_status);
> > > +}
> > > +
> > >  static void sco_sock_init(struct sock *sk, struct sock *parent)
> > >  {
> > >         BT_DBG("sk %p", sk);
> > > @@ -457,6 +467,8 @@ static void sco_sock_init(struct sock *sk, struct sock *parent)
> > >                 sk->sk_type = parent->sk_type;
> > >                 bt_sk(sk)->flags = bt_sk(parent)->flags;
> > >                 security_sk_clone(parent, sk);
> > > +       } else {
> > > +               bt_sk(sk)->skb_put_cmsg = sco_skb_put_cmsg;
> > >         }
> > >  }
> > >
> > > @@ -846,6 +858,18 @@ static int sco_sock_setsockopt(struct socket *sock, int level, int optname,
> > >                 sco_pi(sk)->setting = voice.setting;
> > >                 break;
> > >
> > > +       case BT_PKT_STATUS:
> > > +               if (get_user(opt, (u32 __user *)optval)) {
> > > +                       err = -EFAULT;
> > > +                       break;
> > > +               }
> > > +
> > > +               if (opt)
> > > +                       sco_pi(sk)->cmsg_mask |= SCO_CMSG_PKT_STATUS;
> > > +               else
> > > +                       sco_pi(sk)->cmsg_mask &= ~SCO_CMSG_PKT_STATUS;
> > > +               break;
> > > +
> > >         default:
> > >                 err = -ENOPROTOOPT;
> > >                 break;
> > > @@ -923,6 +947,7 @@ static int sco_sock_getsockopt(struct socket *sock, int level, int optname,
> > >         int len, err = 0;
> > >         struct bt_voice voice;
> > >         u32 phys;
> > > +       u32 pkt_status;
> > >
> > >         BT_DBG("sk %p", sk);
> > >
> > > @@ -969,6 +994,16 @@ static int sco_sock_getsockopt(struct socket *sock, int level, int optname,
> > >                         err = -EFAULT;
> > >                 break;
> > >
> > > +       case BT_PKT_STATUS:
> > > +               if (sco_pi(sk)->cmsg_mask & SCO_CMSG_PKT_STATUS)
> > > +                       pkt_status = 1;
> > > +               else
> > > +                       pkt_status = 0;
> > > +
> > > +               if (put_user(pkt_status, (u32 __user *)optval))
> > > +                       err = -EFAULT;
> > > +               break;
> > > +
> > >         default:
> > >                 err = -ENOPROTOOPT;
> > >                 break;
> > > --
> > > 2.27.0.rc2.251.g90737beb825-goog
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz


-- 
Luiz Augusto von Dentz