netdev - Re: [PATCH] Bluetooth: hci_event: Add support for handling LE BIG Sync Lost event

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Message-ID: <CABBYNZKhTOWGXRWe5EYP0Mp3ynO5TmV-zgE43AVmNgm-=01gbg@mail.gmail.com>
Date: Tue, 24 Jun 2025 12:56:42 -0400
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: yang.li@...ogic.com
Cc: Marcel Holtmann <marcel@...tmann.org>, Johan Hedberg <johan.hedberg@...il.com>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: hci_event: Add support for handling LE BIG
 Sync Lost event

Hi,

On Tue, Jun 24, 2025 at 1:20 AM Yang Li via B4 Relay
<devnull+yang.li.amlogic.com@...nel.org> wrote:
>
> From: Yang Li <yang.li@...ogic.com>
>
> When the BIS source stops, the controller sends an LE BIG Sync Lost
> event (subevent 0x1E). Currently, this event is not handled, causing
> the BIS stream to remain active in BlueZ and preventing recovery.
>
> Signed-off-by: Yang Li <yang.li@...ogic.com>
> ---
>  include/net/bluetooth/hci.h |  6 ++++++
>  net/bluetooth/hci_event.c   | 23 +++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
>
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index 82cbd54443ac..48389a64accb 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -2849,6 +2849,12 @@ struct hci_evt_le_big_sync_estabilished {
>         __le16  bis[];
>  } __packed;
>
> +#define HCI_EVT_LE_BIG_SYNC_LOST 0x1e
> +struct hci_evt_le_big_sync_lost {
> +       __u8    handle;
> +       __u8    reason;
> +} __packed;
> +
>  #define HCI_EVT_LE_BIG_INFO_ADV_REPORT 0x22
>  struct hci_evt_le_big_info_adv_report {
>         __le16  sync_handle;
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 66052d6aaa1d..730deaf1851f 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -7026,6 +7026,24 @@ static void hci_le_big_sync_established_evt(struct hci_dev *hdev, void *data,
>         hci_dev_unlock(hdev);
>  }
>
> +static void hci_le_big_sync_lost_evt(struct hci_dev *hdev, void *data,
> +                                           struct sk_buff *skb)
> +{
> +       struct hci_evt_le_big_sync_lost *ev = data;
> +       struct hci_conn *conn;
> +
> +       bt_dev_dbg(hdev, "BIG Sync Lost: big_handle 0x%2.2x", ev->handle);
> +
> +       hci_dev_lock(hdev);
> +
> +       list_for_each_entry(conn, &hdev->conn_hash.list, list) {
> +               if (test_bit(HCI_CONN_BIG_SYNC, &conn->flags))
> +                       hci_disconn_cfm(conn, HCI_ERROR_REMOTE_USER_TERM);
> +       }

Let's start with the obvious problems:

1. This does not use the handle, instead it disconnects all the
connections with HCI_CONN_BIG_SYNC
2. It doesn't use the reason either
3. hci_disconnect_cfm should be followed with hci_conn_del to free the hci_conn

So this does tell me you don't fully understand what you are doing, I
hope I am not dealing with some AI generated code otherwise I would
just do it myself.

> +       hci_dev_unlock(hdev);
> +}
> +
>  static void hci_le_big_info_adv_report_evt(struct hci_dev *hdev, void *data,
>                                            struct sk_buff *skb)
>  {
> @@ -7149,6 +7167,11 @@ static const struct hci_le_ev {
>                      hci_le_big_sync_established_evt,
>                      sizeof(struct hci_evt_le_big_sync_estabilished),
>                      HCI_MAX_EVENT_SIZE),
> +       /* [0x1e = HCI_EVT_LE_BIG_SYNC_LOST] */
> +       HCI_LE_EV_VL(HCI_EVT_LE_BIG_SYNC_LOST,
> +                    hci_le_big_sync_lost_evt,
> +                    sizeof(struct hci_evt_le_big_sync_lost),
> +                    HCI_MAX_EVENT_SIZE),
>         /* [0x22 = HCI_EVT_LE_BIG_INFO_ADV_REPORT] */
>         HCI_LE_EV_VL(HCI_EVT_LE_BIG_INFO_ADV_REPORT,
>                      hci_le_big_info_adv_report_evt,
>
> ---
> base-commit: bd35cd12d915bc410c721ba28afcada16f0ebd16
> change-id: 20250612-handle_big_sync_lost_event-4c7dc64390a2
>
> Best regards,
> --
> Yang Li <yang.li@...ogic.com>
>
>


-- 
Luiz Augusto von Dentz