Re: [PATCH AUTOSEL 5.10 15/15] Bluetooth: hci_uart: fix race during initialization

Pavel Machek
2025-04-18T17:03:18Z

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Hi!

> From: Arseniy Krasnov <avkrasnov@salutedevices.com>
>
> [ Upstream commit 366ceff495f902182d42b6f41525c2474caf3f9a ]
>
> '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 moves setting of 'HCI_UART_PROTO_READY' before calling function
> 'hci_uart_register_dev()'.

Ok, but do we need to adjust the error handling?

> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -706,12 +706,13 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
>
> hu->proto = p;
>
> + set_bit(HCI_UART_PROTO_READY, &hu->flags);
> +
> err = hci_uart_register_dev(hu);
> if (err) {
> return err;
> }
>
> - set_bit(HCI_UART_PROTO_READY, &hu->flags);
> return 0;
> }

Should we clear the bit in the error path to undo the effects?

Best regards,
Pavel
--
DENX Software Engineering GmbH, Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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