sysv test: properly wait for children

[vangyzen]

Summary

In the msg and shm tests, if the child exited before the parent
entered sigsuspend(), the test would hang and time out. This was
also a problem in the sem test, but the misuse of atf_tc_pass()
masked it. Adding a short sleep before the sigsuspend() calls made
the hang 100% reliable. With the same sleep in the new version,
the test passes reliably.

Remove calls to atf_tc_pass(). The call in the sem test broke the test
by exiting prematurely, after only one child out of five had finished.
The other two were harmless but unhelpful.

Reduce a one-second sleep to a more reasonable duration so I can quickly
run many iterations of the test.

Re-enable the test in CI.

PR: 233649
MFC after: 1 week
Sponsored by: Dell EMC Isilon

[markj]

Seems rather bizarre not to use wait() to begin with. I can't see a reason why it was done this way. :/

contrib/netbsd-tests/kernel/t_sysv.c

681

Maybe assert that wait_result == child_pid just for good measure?

[vangyzen]

• Review feedback, and more

[vangyzen]

In D35187#797770, @markj wrote:

Seems rather bizarre not to use wait() to begin with. I can't see a reason why it was done this way. :/

My thoughts exactly. I actually looked for any unusual, specific interaction between signals and these SysV facilities, and of course found none.

Sorry for the large update. This code just keeps on giving.