[Devel] [PATCH rh7 1/2] vdso: virtualized monotonic gettime through vdso

[Dmitry Safonov]

On 05/24/2017 07:45 PM, Dmitry Safonov wrote:
> On 05/24/2017 07:45 PM, Andrey Ryabinin wrote:
>>
>>
>> On 05/24/2017 07:38 PM, Dmitry Safonov wrote:
>>> On 05/24/2017 07:34 PM, Andrey Ryabinin wrote:
>>>>
>>>>
>>>> On 05/24/2017 07:29 PM, Dmitry Safonov wrote:
>>>>> On 05/24/2017 06:21 PM, Andrey Ryabinin wrote:
>>>>>> We already have infrastructure for virtualized vdso, however we use
>>>>>> it only to change LINUX_VERSION_NAME in container. Simply store 
>>>>>> container's
>>>>>> start time - ve->start_timespec in vdso variable - 
>>>>>> VDSO64_ve_start_timespec,
>>>>>> and use it in __vdso_clock_gettime() to calculate container's 
>>>>>> monotonic time.
>>>>>>
>>>>>> Make 
>>>>>> uts_arch_setup_additional_pages()/uts_prep_vdso_pages_locked() to 
>>>>>> always
>>>>>> setup new vdso, since previous policy to setup vdso only if 
>>>>>> uts_ns->name.release
>>>>>> wouldn't work for virtualized __vdso_clock_gettime()
>>>>>>
>>>>>> https://jira.sw.ru/browse/PSBM-66451
>>>>>> Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
>>>>>
>>>>> Well, that's all looks good, but I've two questions:
>>>>>
>>>>> 1. Where VDSO64_ve_start_timespec is set? I do not see that part.
>>>>>
>>>>
>>>> in uts_arch_setup_additional_pages() and uts_prep_vdso_pages_locked()
>>>
>>> Uhm, yes, but that means that ve_ts_write() is broken for
>>> running CT.
>>>
>>
>> Do we care? Changing monotonic time on the fly doesn't sound like a 
>> brilliant idea.
> 
> Ok, if that's not used by vz tools, then:
> Reviewed-by: Dmitry Safonov <dsafonov at virtuozzo.com>

What I suggest - may we add a third patch that changes ve_ts_write()
to return -EACCESS or something if vdso pages array already exists for
UTS ns?

-- 
              Dmitry