[CRIU] test/others/rpc test cases

[Dmitry Safonov]

2018-05-23 22:26 GMT+01:00 Andrei Vagin <avagin at virtuozzo.com>:
> On Wed, May 16, 2018 at 05:16:12PM +0100, Dmitry Safonov wrote:
>> 2018-05-16 16:52 GMT+01:00 Adrian Reber <adrian at lisas.de>:
>> > Hello Andrei,
>> >
>> > we quickly chatted about the tests in test/others/rpc and I had a look
>> > at it.
>> >
>> > One test (errno.py) dumps itself, keeps on running and tries to restore
>> > itself. This should (and does fail) as the PID is already in use by the
>> > test case. The test case wants to to test the error handling of 'criu
>> > service'. But CRIU just kills all processes which it failed to restore
>> > in criu/cr-restore.c (around line 2240 : kill(vpid(pi), SIGKILL);).
>> >
>> > As the test case is killed by CRIU it counts as a failure. I guess this
>> > used to work at some point in time, but with 3.8.1 it does not.
>> >
>> > I am not sure what the right solution is. Should CRIU kill a process if
>> > restore fails, probably to make sure that no half restored process still
>> > exists. Maybe the test case does not make sense anymore...
>> >
>> > Do you have any thoughts on this? Is this a CRIU bug or a wrong test case?
>>
>> It looks to me like a valid test. CRIU shouldn't kill existing tasks with
>> reused PID. Do we run this errno.py on Travis?
>>
>> I haven't even compile tested, but something like this might fix?
>>
>> --->8---
>> --- a/criu/cr-restore.c
>> +++ b/criu/cr-restore.c
>> @@ -1510,6 +1510,7 @@ static int do_fork_with_pid(struct pstree_item
>> *item, struct ns_id *pid_ns, stru
>>         if (pid < 0) {
>>                 pr_perror("Can't clone()");
>>                 ret = -1;
>> +               hlp_pid->ns[i].virt = -1;
>
> If we have three processes A -> B -> C. PID-s of B, C have been reused.
> With you patch, virt for B will be set to -1, but a process with the C
> pid will be killed.
>
> I think something like this should fix a problem:

Yeah, probably - I haven't looked at the issue closely, only glanced
and that diff looked meaningful, altrough it had a chance to be comple
and utter garbage.

> @@ -2556,8 +2556,8 @@ out_kill:
>                 struct pstree_item *pi;
>
>                 for_each_pstree_item(pi)
> -                       if (vpid(pi) > 0)
> -                               kill(vpid(pi), SIGKILL);
> +                       if (pi->pid->real > 0)
> +                               kill(pi->pid->real, SIGKILL);

Nice!

Thanks,
             Dmitry