Hi Arseniy,
On Wed, Nov 27, 2024 at 7:38 AM Arseniy Krasnov
<avkrasnov@xxxxxxxxxxxxxxxxx> wrote:
>
> 'hci_register_dev()' calls power up function, which is executed by
> kworker - 'hci_power_on()'. This function does access to bluetooth chip
> using callbacks from 'hci_ldisc.c', for example 'hci_uart_send_frame()'.
> Now 'hci_uart_send_frame()' checks 'HCI_UART_PROTO_READY' bit set, and
> if not - it fails. Problem is that 'HCI_UART_PROTO_READY' is set after
> 'hci_register_dev()', and there is tiny chance that 'hci_power_on()' will
> be executed before setting this bit. In that case HCI init logic fails.
>
> Patch adds one more bit in addition to 'HCI_UART_PROTO_READY' which
> allows to perform power up logic without original bit set.
>
> Signed-off-by: Arseniy Krasnov <avkrasnov@xxxxxxxxxxxxxxxxx>
> ---
> drivers/bluetooth/hci_ldisc.c | 19 ++++++++++++++-----
> drivers/bluetooth/hci_uart.h | 1 +
> 2 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
> index 30192bb083549..2e20f00649bd7 100644
> --- a/drivers/bluetooth/hci_ldisc.c
> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -102,7 +102,8 @@ static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
> if (!skb) {
> percpu_down_read(&hu->proto_lock);
>
> - if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
> + if (test_bit(HCI_UART_PROTO_READY, &hu->flags) ||
> + test_bit(HCI_UART_PROTO_INIT, &hu->flags))
> skb = hu->proto->dequeue(hu);
>
> percpu_up_read(&hu->proto_lock);
> @@ -124,7 +125,8 @@ int hci_uart_tx_wakeup(struct hci_uart *hu)
> if (!percpu_down_read_trylock(&hu->proto_lock))
> return 0;
>
> - if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
> + if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
> + !test_bit(HCI_UART_PROTO_INIT, &hu->flags))
> goto no_schedule;
>
> set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
> @@ -278,7 +280,8 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
>
> percpu_down_read(&hu->proto_lock);
>
> - if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
> + if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
> + !test_bit(HCI_UART_PROTO_INIT, &hu->flags)) {
> percpu_up_read(&hu->proto_lock);
> return -EUNATCH;
> }
> @@ -582,7 +585,8 @@ static void hci_uart_tty_wakeup(struct tty_struct *tty)
> if (tty != hu->tty)
> return;
>
> - if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
> + if (test_bit(HCI_UART_PROTO_READY, &hu->flags) ||
> + test_bit(HCI_UART_PROTO_INIT, &hu->flags))
> hci_uart_tx_wakeup(hu);
> }
>
> @@ -608,7 +612,8 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
>
> percpu_down_read(&hu->proto_lock);
>
> - if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
> + if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
> + !test_bit(HCI_UART_PROTO_INIT, &hu->flags)) {
> percpu_up_read(&hu->proto_lock);
> return;
> }
> @@ -704,12 +709,16 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
>
> hu->proto = p;
>
> + set_bit(HCI_UART_PROTO_INIT, &hu->flags);
> +
> err = hci_uart_register_dev(hu);
> if (err) {
> return err;
> }
>
> set_bit(HCI_UART_PROTO_READY, &hu->flags);
> + clear_bit(HCI_UART_PROTO_INIT, &hu->flags);
This should be quite obvious, why don't you just move the
HCI_UART_PROTO_READY above hci_uart_register_dev?
> return 0;
> }
>
> diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
> index 00bf7ae82c5b7..39f39704be41f 100644
> --- a/drivers/bluetooth/hci_uart.h
> +++ b/drivers/bluetooth/hci_uart.h
> @@ -89,6 +89,7 @@ struct hci_uart {
> #define HCI_UART_REGISTERED 1
> #define HCI_UART_PROTO_READY 2
> #define HCI_UART_NO_SUSPEND_NOTIFIER 3
> +#define HCI_UART_PROTO_INIT 4
>
> /* TX states */
> #define HCI_UART_SENDING 1
> --
> 2.30.1
--
Luiz Augusto von Dentz
