Hi, Johan Hovold <jo...@kernel.org> writes: > On Tue, Jun 11, 2019 at 08:24:16PM +0300, Felipe Balbi wrote: >> If we happen to have two XHCI controllers with DbC capability, then >> there's no hope this will ever work as the global pointer will be >> overwritten by the controller that probes last. >> >> Avoid this problem by keeping the tty_driver struct pointer inside >> struct xhci_dbc. > > How did you test this patch?
by running it on a machine that actually has two DbCs
>> @@ -279,52 +279,52 @@ static const struct tty_operations dbc_tty_ops = {
>> .unthrottle = dbc_tty_unthrottle,
>> };
>>
>> -static struct tty_driver *dbc_tty_driver;
>> -
>> int xhci_dbc_tty_register_driver(struct xhci_hcd *xhci)
>> {
>> int status;
>> struct xhci_dbc *dbc = xhci->dbc;
>>
>> - dbc_tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
>> + dbc->tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
>> TTY_DRIVER_DYNAMIC_DEV);
>> - if (IS_ERR(dbc_tty_driver)) {
>> - status = PTR_ERR(dbc_tty_driver);
>> - dbc_tty_driver = NULL;
>> + if (IS_ERR(dbc->tty_driver)) {
>> + status = PTR_ERR(dbc->tty_driver);
>> + dbc->tty_driver = NULL;
>> return status;
>> }
>>
>> - dbc_tty_driver->driver_name = "dbc_serial";
>> - dbc_tty_driver->name = "ttyDBC";
>> + dbc->tty_driver->driver_name = "dbc_serial";
>> + dbc->tty_driver->name = "ttyDBC";
>
> You're now registering multiple drivers for the same thing (and wasting
> a major number for each) and specifically using the same name, which
> should lead to name clashes when registering the second port.
No warnings were printed while running this, actually. Odd
--
balbi
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