[PATCH] posix/tst-spawn: Fix racy tests in spawned processes.

[Adhemerval Zanella]

On 28/01/2019 12:15, Stefan Liebler wrote:
> On 01/28/2019 02:41 PM, Stefan Liebler wrote:
>> Hi,
>>
>> from time to time I get fails in tst-spawn like:
>> tst-spawn.c:111: numeric comparison failure
>> Â Â Â  left: 0 (0x0); from: xlseek (fd2, 0, SEEK_CUR)
>> Â Â  right: 28 (0x1c); from: strlen (fd2string)
>> error: 1 test failures
>> tst-spawn.c:252: numeric comparison failure
>> Â Â Â  left: 1 (0x1); from: WEXITSTATUS (status)
>> Â Â  right: 0 (0x0); from: 0
>> error: 1 test failures
>>
>> It turned out, that a child process is testing it's open file descriptors with e.g. a sequence of testing the current position, setting the position to zero and reading a specific amount of bytes.
>>
>> Unfortunately starting with commit 2a69f853c03034c2e383e0f9c35b5402ce8b5473 the test is spawning a second child process which is sharing some of the file descriptors.  If the test sequence as mentioned above is running in parallel it leads to test failures.
>>
>> As the second call of posix_spawn shall test a NULL pid argument, this patch is just moving the waitpid of the first child before the posix_spawn of the second child.
>>
>> Okay for commit?
>> (I assume 2.30)
>>
>> Bye,
>> Stefan
>>
>> ChangeLog:
>>
>> Â Â Â Â Â * posix/tst-spawn do_test(): Move waitpid before posix_spawn.
>>
> 
> Sorry. Forgot to attach the patch.

LGTM to 2.30, thanks for catching it.