Re: [PATCH v6] xen/console: introduce domain_console struct

[dmkhn@proton.me]

On Fri, Jul 11, 2025 at 07:59:27AM +0200, Jan Beulich wrote:
> On 11.07.2025 03:07, dmkhn@proton.me wrote:
> > On Thu, Jul 10, 2025 at 01:16:24PM +0200, Jan Beulich wrote:
> >> On 10.07.2025 03:35, dmkhn@proton.me wrote:
> >>> @@ -877,6 +873,16 @@ struct domain *domain_create(domid_t domid,
> >>>
> >>>      /* All error paths can depend on the above setup. */
> >>>
> >>> +    BUILD_BUG_ON(DOMAIN_CONSOLE_BUF_SIZE <= 0);
> >>
> >> While the "equals 0" case can in principle happen, the "less than" part
> >> is dead code (and hence this needs checking differently): The type of
> >> DOMAIN_CONSOLE_BUF_SIZE is an unsigned one, so wrapping through 0 will
> >> yield huge positive values.
> >>
> >>> +    err = -ENOMEM;
> >>> +    d->console = xzalloc_bytes(DOMAIN_CONSOLE_SIZE);
> >>
> >> As previously indicated, new code ought to use the xv*alloc family of
> >> functions, which deliberately doesn't include any ..._bytes() forms.
> >> Note how instead there is xvzalloc_flex_struct() for situations like
> >> the one here.
> >
> > Looks like xvzalloc_flex_struct() is not used anywhere in the code base...
> 
> And what do you mean to tell me by that? xvmalloc_flex_struct() is used,
> and x[mz]alloc_flex_struct() uses are still in need of conversion (which
> is going to be a slow-going process).

Just an observation; I was not aware of these APIs and I was not aware that
there's some slow-going process of switching to preferred use of
xvzalloc_flex_struct().

> 
> Jan