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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Thu, 27 Jul 2023 14:14:27 -0700
Message-ID: <CABBYNZK-im2S7KnbBuP7Bq4V8yvJa-KZ5fZkW7zySepDY9DNTA@mail.gmail.com>
Subject: Re: [PATCH RFC 6/6] Bluetooth: ISO: handle bound CIS cleanup via hci_conn
To:     Pauli Virtanen <pav@iki.fi>
Cc:     linux-bluetooth@vger.kernel.org
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Hi Pauli,

On Wed, Jul 26, 2023 at 2:37=E2=80=AFPM Pauli Virtanen <pav@iki.fi> wrote:
>
> Calling hci_conn_del in __iso_sock_close is invalid. It needs
> hdev->lock, but it cannot be acquired there due to lock ordering.
>
> Fix this by doing cleanup via hci_conn_drop.
>
> Return hci_conn with refcount 1 from hci_bind_cis and hci_connect_cis,
> so that the iso_conn always holds one reference.  This also fixes
> refcounting when error handling.
>
> Since hci_conn_abort shall handle termination of connections in any
> state properly, we can handle BT_CONNECT socket state in the same way as
> BT_CONNECTED.
>
> Signed-off-by: Pauli Virtanen <pav@iki.fi>
> ---
>  net/bluetooth/hci_conn.c |  5 +++++
>  net/bluetooth/iso.c      | 14 +-------------
>  2 files changed, 6 insertions(+), 13 deletions(-)
>
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index ba339a0eb851..33fbdc8e0748 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -1901,6 +1901,8 @@ struct hci_conn *hci_bind_cis(struct hci_dev *hdev,=
 bdaddr_t *dst,
>                 return ERR_PTR(-EINVAL);
>         }
>
> +       hci_conn_hold(cis);
> +
>         cis->iso_qos =3D *qos;
>         cis->state =3D BT_BOUND;
>
> @@ -2254,6 +2256,9 @@ struct hci_conn *hci_connect_cis(struct hci_dev *hd=
ev, bdaddr_t *dst,
>                 return ERR_PTR(-ENOLINK);
>         }
>
> +       /* Link takes the refcount */
> +       hci_conn_drop(cis);
> +
>         cis->state =3D BT_CONNECT;
>
>         hci_le_create_cis_pending(hdev);
> diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
> index cbe3299b4a41..358954bfbb32 100644
> --- a/net/bluetooth/iso.c
> +++ b/net/bluetooth/iso.c
> @@ -628,6 +628,7 @@ static void __iso_sock_close(struct sock *sk)
>                 iso_sock_cleanup_listen(sk);
>                 break;
>
> +       case BT_CONNECT:
>         case BT_CONNECTED:
>         case BT_CONFIG:
>                 if (iso_pi(sk)->conn->hcon) {
> @@ -643,19 +644,6 @@ static void __iso_sock_close(struct sock *sk)
>                 break;
>
>         case BT_CONNECT2:
> -               iso_chan_del(sk, ECONNRESET);
> -               break;
> -       case BT_CONNECT:
> -               /* In case of DEFER_SETUP the hcon would be bound to CIG =
which
> -                * needs to be removed so just call hci_conn_del so the c=
leanup
> -                * callback do what is needed.
> -                */
> -               if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags) &&
> -                   iso_pi(sk)->conn->hcon) {
> -                       hci_conn_del(iso_pi(sk)->conn->hcon);
> -                       iso_pi(sk)->conn->hcon =3D NULL;
> -               }
> -
>                 iso_chan_del(sk, ECONNRESET);
>                 break;
>         case BT_DISCONN:
> --
> 2.41.0

I guess this sort of fix can be sent separately which I guess helps
here since we can prioritize the ones that don't have side effects.

--=20
Luiz Augusto von Dentz