Re: [PATCH v2] Bluetooth: hci_uart: fix race during initialization

[Arseniy Krasnov]

Hi, sorry i'm new in bluetooth subsystem. I get the following
message from CI:
https://patchwork.kernel.org/project/bluetooth/list/?series=918554
Where one of tests was failed. Where I can get more information
about failure:

tedd_an/TestRunner_mgmt-tester 	fail 	TestRunner_mgmt-tester: Total: 490, Passed: 483 (98.6%), Failed: 3, Not Run: 4 

?

Thanks

On 17.12.2024 11:12, Arseniy Krasnov 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 moves setting of 'HCI_UART_PROTO_READY' before calling function
> 'hci_uart_register_dev()'.
> 
> Signed-off-by: Arseniy Krasnov <avkrasnov@xxxxxxxxxxxxxxxxx>
> ---
>  Changelog v1->v2:
>  * Move 'set_bit()' before 'hci_uart_register_dev()' instead of
>    adding new bit 'HCI_UART_PROTO_INIT'.
> 
>  drivers/bluetooth/hci_ldisc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
> index 30192bb083549..07b9aa09bbe2e 100644
> --- a/drivers/bluetooth/hci_ldisc.c
> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -704,12 +704,13 @@ 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;
>  }
>