Re: [PATCH v3 2/5] xen/console: introduce console_get_domid()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.05.2025 22:12, dmkhn@xxxxxxxxx wrote:
> --- a/xen/arch/arm/vpl011.c
> +++ b/xen/arch/arm/vpl011.c
> @@ -78,12 +78,11 @@ static void vpl011_write_data_xen(struct domain *d, 
> uint8_t data)
>      unsigned long flags;
>      struct vpl011 *vpl011 = &d->arch.vpl011;
>      struct vpl011_xen_backend *intf = vpl011->backend.xen;
> -    struct domain *input = console_get_domain();
>  
>      VPL011_LOCK(d, flags);
>  
>      intf->out[intf->out_prod++] = data;
> -    if ( d == input )
> +    if ( d->domain_id == console_get_domid() )

How do you know d isn't a domain different from the one that was the
console "owner" prior to being destroyed? Original code guaranteed this
up to ...

> @@ -123,8 +122,6 @@ static void vpl011_write_data_xen(struct domain *d, 
> uint8_t data)
>      vpl011_update_interrupt_status(d);
>  
>      VPL011_UNLOCK(d, flags);
> -
> -    console_put_domain(input);

... here.

Jan