[LTP] [PATCH] shmget03: fix test when some shm segments already exist

[xuyang2018.jy@fujitsu.com <xuyang2018.jy@fujitsu.com>]

Hi All
> Hi!
>>>> Yes, good point, that would be more precise for ENOSPC testing.
>>> AFAIK, ltp doesn't support parallel test now. I think parallel test
>>> maybe a future plan that is why we use docparase to collect each case's
>>> used resources(so we can convert many groups, like pid, memory, disk
>>> space..., then we can run pid group and memory groups test case parallelly).
>> Yes, parallel support is not supported atm. Richie and Cyril has done some work
>> on runltp-ng to support it. Yes, first it's needed to add support in resources
>> (docparse), see Cyril's old block post [1].
>
> Besides most of the SHM tests will crash and burn if executed in
> parallel. The SysV IPC shares a global namespace and because of that we
> can't really write tests without assuming that we are the only one
> manipulating them when the test is executed.
I guess we should reach a consensus that how to fix this problem
1)use for loop to trigger this error
2)use CLONE_NEWIPC to trigger this error
3)Or we are the only one that use shm and we can add a api to count the 
existed_cnt

ps: I don't want to leave this problem too long time.

Best Regards
Yang Xu
>