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SubjectRe: [PATCH] Bluetooth: hci_core: fix init with HCI_QUIRK_NON_PERSISTENT_SETUP
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Hi Mattijs,

> Some HCI devices which have the HCI_QUIRK_NON_PERSISTENT_SETUP [1]
> require a call to setup() to be ran after every open().
>
> During the setup() stage, these devices expect the chip to acknowledge
> its setup() completion via vendor specific frames.
>
> If userspace opens() such HCI device in HCI_USER_CHANNEL [2] mode,
> the vendor specific frames are never tranmitted to the driver, as
> they are filtered in hci_rx_work().
>
> Allow HCI devices which have HCI_QUIRK_NON_PERSISTENT_SETUP to process
> frames if the HCI device is is HCI_INIT state.
>
> [1] https://lore.kernel.org/patchwork/patch/965071/
> [2] https://www.spinics.net/lists/linux-bluetooth/msg37345.html
>
> Fixes: 740011cfe948 ("Bluetooth: Add new quirk for non-persistent setup settings")
> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
> ---
> Some more background on the change follows:
>
> The Android bluetooth stack (Bluedroid) also has a HAL implementation
> which follows Linux's standard rfkill interface [1].
>
> This implementation relies on the HCI_CHANNEL_USER feature to get
> exclusive access to the underlying bluetooth device.
>
> When testing this along with the btkmtksdio driver, the
> chip appeared unresponsive when calling the following from userspace:
>
> struct sockaddr_hci addr;
> int fd;
>
> fd = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
>
> memset(&addr, 0, sizeof(addr));
> addr.hci_family = AF_BLUETOOTH;
> addr.hci_dev = 0;
> addr.hci_channel = HCI_CHANNEL_USER;
>
> bind(fd, (struct sockaddr *) &addr, sizeof(addr)); # device hangs
>
> In the case of bluetooth drivers exposing QUIRK_NON_PERSISTENT_SETUP
> such as btmtksdio, setup() is called each multiple times.
> In particular, when userspace calls bind(), the setup() is called again
> and vendor specific commands might be send to re-initialize the chip.
>
> Those commands are filtered out by hci_core in HCI_CHANNEL_USER mode,
> preventing setup() from completing successfully.
>
> This has been tested on a 4.19 kernel based on Android Common Kernel.
> It has also been compile tested on bluetooth-next.
>
> [1] https://android.googlesource.com/platform/system/bt/+/refs/heads/master/vendor_libs/linux/interface/
>
> net/bluetooth/hci_core.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 04bc79359a17..5f12e8574d54 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -4440,9 +4440,20 @@ static void hci_rx_work(struct work_struct *work)
> hci_send_to_sock(hdev, skb);
> }
>
> + /* If the device has been opened in HCI_USER_CHANNEL,
> + * the userspace has exclusive access to device.
> + * When HCI_QUIRK_NON_PERSISTENT_SETUP is set and
> + * device is HCI_INIT, we still need to process
> + * the data packets to the driver in order
> + * to complete its setup().
> + */
> if (hci_dev_test_flag(hdev, HCI_USER_CHANNEL)) {
> - kfree_skb(skb);
> - continue;
> + if (!test_bit(HCI_QUIRK_NON_PERSISTENT_SETUP,
> + &hdev->quirks) ||
> + !test_bit(HCI_INIT, &hdev->flags)) {
> + kfree_skb(skb);
> + continue;
> + }
> }

if (hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
!test_bit(HCI_INIT, &hdev->flags)) {
kfree_skb(skb);
continue;
}

Wouldn’t it be enough to just add a check for HCI_INIT to this. I mean it makes no difference if ->setup is repeated on each device open or not. We want to process event during HCI_INIT when in user channel mode.

Regards

Marcel

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