lkml.org 
[lkml]   [2018]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 5/9] drm/xen-front: Implement handling of shared display buffers
From
Date
On 02/23/2018 04:36 PM, Boris Ostrovsky wrote:
> On 02/23/2018 02:53 AM, Oleksandr Andrushchenko wrote:
>> On 02/23/2018 02:25 AM, Boris Ostrovsky wrote:
>>> On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote:
>>>> static int __init xen_drv_init(void)
>>>> {
>>>> + /* At the moment we only support case with XEN_PAGE_SIZE ==
>>>> PAGE_SIZE */
>>>> + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
>>> Why BUILD_BUG_ON? This should simply not load if page sizes are
>>> different.
>>>
>>>
>> This is a compile time check, so if kernel/Xen is configured
>> to use page size combination which is not supported by the
>> driver it will fail during compilation. This seems correct to me,
>> because you shouldn't even try to load the driver which
>> cannot handle different page sizes to not make any harm.
>
> This will prevent whole kernel from building. So, for example,
> randconfig builds will fail.
>
makes a lot of sense, thank you
will rework so I reject to load if the requirement is not met
>>>
>>>
>>>> + ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);
>>>> + BUG_ON(ret);
>>> We should try not to BUG*(). There are a few in this patch (and possibly
>>> others) that I think can be avoided.
>>>
>> I will rework BUG_* for map/unmap code to handle errors,
>> but will still leave
>> /* either pages or sgt, not both */
>> BUG_ON(cfg->pages && cfg->sgt);
>> which is a real driver bug and must not happen
> Why not return an error?
>
> In fact, AFAICS you only call it in patch 9 where both of these can be
> tested, in which case something like -EINVAL would look reasonable.
ok, will remove BUG_ON as well
> -boris

\
 
 \ /
  Last update: 2018-02-23 15:46    [W:0.101 / U:0.920 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site