Hi Felipe,
On Mon, Mar 13, 2017 at 7:54 PM, Felipe F. Tonello <eu@xxxxxxxxxxxxxxxxx> wrote:
> There is a need for certain LE profiles (MIDI for example) to change the
> current connection's parameters. In order to do that, this patch
> introduces a new BT_LE_CONN_PARAM socket option for SOL_BLUETOOTH
> protocol which allow user-space l2cap sockets to update the current
> connection.
>
> It necessary to expose all the connection parameters to user-space
> because user-space are exposed to those values anyway, via PPCP
> characteristic or Slave Connection Interval AD, for instance. Also it is
> useful for tools to set particular values for because of profile
> requirements.
>
> If ROLE is SLAVE, then it will also send a L2CAP_CONN_PARAM_UPDATE_REQ
> signaling command to the MASTER, triggering proper 4.0 parameter update
> procedure.
>
> This option will also send a MGMT_EV_NEW_CONN_PARAM event with the
> store_hint set so the user-space application can store the connection
> parameters for persistence reasons.
>
> Note: Connection Parameters Request Link Layer Control Procedure is not
> supported by BlueZ yet.
>
> Signed-off-by: Felipe F. Tonello <eu@xxxxxxxxxxxxxxxxx>
> ---
> include/net/bluetooth/bluetooth.h | 8 +++
> net/bluetooth/l2cap_sock.c | 101 ++++++++++++++++++++++++++++++++++++++
> net/bluetooth/mgmt.c | 1 +
> 3 files changed, 110 insertions(+)
>
> diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> index 01487192f628..ce5b3abd3b27 100644
> --- a/include/net/bluetooth/bluetooth.h
> +++ b/include/net/bluetooth/bluetooth.h
> @@ -122,6 +122,14 @@ struct bt_voice {
> #define BT_SNDMTU 12
> #define BT_RCVMTU 13
>
> +#define BT_LE_CONN_PARAM 14
> +struct bt_le_conn_param {
> + __u16 min_interval;
> + __u16 max_interval;
> + __u16 latency;
> + __u16 supervision_timeout;
> +};
> +
> __printf(1, 2)
> void bt_info(const char *fmt, ...);
> __printf(1, 2)
> diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
> index f307b145ea54..8c2e6f29869f 100644
> --- a/net/bluetooth/l2cap_sock.c
> +++ b/net/bluetooth/l2cap_sock.c
> @@ -515,6 +515,47 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname,
> lock_sock(sk);
>
> switch (optname) {
> + case BT_LE_CONN_PARAM: {
> + struct bt_le_conn_param conn_param;
> + struct hci_conn_params *params;
> + struct hci_conn *hcon;
> + struct hci_dev *hdev;
> +
> + if (!chan->conn) {
> + err = -ENOTCONN;
> + break;
> + }
> +
> + hcon = chan->conn->hcon;
> + hdev = hcon->hdev;
> + hci_dev_lock(hdev);
> +
> + params = hci_conn_params_lookup(hdev, &hcon->dst,
> + hcon->dst_type);
> +
> + memset(&conn_param, 0, sizeof(conn_param));
> +
> + if (params) {
> + conn_param.min_interval = params->conn_min_interval;
> + conn_param.max_interval = params->conn_max_interval;
> + conn_param.latency = params->conn_latency;
> + conn_param.supervision_timeout =
> + params->supervision_timeout;
> + } else {
> + conn_param.min_interval = hdev->le_conn_min_interval;
> + conn_param.max_interval = hdev->le_conn_max_interval;
> + conn_param.latency = hdev->le_conn_latency;
> + conn_param.supervision_timeout = hdev->le_supv_timeout;
> + }
> +
> + hci_dev_unlock(hdev);
> +
> + len = min_t(unsigned int, len, sizeof(conn_param));
> + if (copy_to_user(optval, (char *) &conn_param, len))
> + err = -EFAULT;
> +
> + break;
> + }
> case BT_SECURITY:
> if (chan->chan_type != L2CAP_CHAN_CONN_ORIENTED &&
> chan->chan_type != L2CAP_CHAN_FIXED &&
> @@ -762,6 +803,66 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
> lock_sock(sk);
>
> switch (optname) {
> + case BT_LE_CONN_PARAM: {
> + struct bt_le_conn_param conn_param;
> + struct hci_conn_params *hci_param;
> + struct hci_conn *hcon;
> + struct hci_dev *hdev;
> +
> + len = min_t(unsigned int, sizeof(conn_param), optlen);
> + if (copy_from_user((char *) &conn_param, optval, len)) {
> + err = -EFAULT;
> + break;
> + }
> +
> + if (!chan->conn) {
> + err = -ENOTCONN;
> + break;
> + }
> +
> + err = hci_check_conn_params(conn_param.min_interval,
> + conn_param.max_interval, conn_param.latency,
> + conn_param.supervision_timeout);
> + if (err < 0) {
> + BT_ERR("Ignoring invalid connection parameters");
> + break;
> + }
> +
> + hcon = chan->conn->hcon;
> + hdev = hcon->hdev;
> +
> + hci_dev_lock(hdev);
> +
> + /* We add new param in case it doesn't exist.
> + * hci_param will be updated in hci_le_conn_update(). */
> + hci_param = hci_conn_params_add(hdev, &hcon->dst,
> + hcon->dst_type);
> + if (!hci_param) {
> + err = -ENOMEM;
> + BT_ERR("Failed to add connection parameters");
> + hci_dev_unlock(hcon->hdev);
> + break;
> + }
> +
> + hci_dev_unlock(hdev);
> +
> + /* Send a L2CAP connection parameters update request, if
> + * the host role is slave. */
> + l2cap_le_conn_req(chan->conn, conn_param.min_interval,
> + conn_param.max_interval, conn_param.latency,
> + conn_param.supervision_timeout);
I thought we already discuss doing something like this should require
us to wait for the response from the remote, if it doesn't accept the
new parameters or suggests something else then it needs to be stored
accordingly. Also perhaps the socket options should only work as
overwrite values for the current connection and not affect the stored
values because this may be relevant for only a certain cid/PSM and if
that is not reconnected there is no reason to reapply the same
parameters all the time.
> + /* this function also updates the hci_param value */
> + hci_le_conn_update(hcon, conn_param.min_interval,
> + conn_param.max_interval, conn_param.latency,
> + conn_param.supervision_timeout);
> +
> + mgmt_new_conn_param(hdev, &hcon->dst, hcon->dst_type, true,
> + conn_param.min_interval, conn_param.max_interval,
> + conn_param.latency, conn_param.supervision_timeout);
> + break;
> + }
> +
> case BT_SECURITY:
> if (chan->chan_type != L2CAP_CHAN_CONN_ORIENTED &&
> chan->chan_type != L2CAP_CHAN_FIXED &&
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 1fba2a03f8ae..0f44af559ae6 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -5540,6 +5540,7 @@ static int load_conn_param(struct sock *sk, struct hci_dev *hdev, void *data,
> hci_param->conn_max_interval = max;
> hci_param->conn_latency = latency;
> hci_param->supervision_timeout = timeout;
> + hci_param->conn_config = BT_LE_CONN_CONFIG_CUSTOM_LATENCY;
> }
>
> hci_dev_unlock(hdev);
> --
> 2.12.0
>
> --
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--
Luiz Augusto von Dentz
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