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

[Stefan Liebler]

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  left: 0 (0x0); from: xlseek (fd2, 0, SEEK_CUR)
>  Â  right: 28 (0x1c); from: strlen (fd2string)
> error: 1 test failures
> tst-spawn.c:252: numeric comparison failure
>  Â Â  left: 1 (0x1); from: WEXITSTATUS (status)
>  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 * posix/tst-spawn do_test(): Move waitpid before posix_spawn.
> 

Sorry. Forgot to attach the patch.
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