[PATCH] posix: Do not use WNOHANG in waitpid call for Linux posix_spawn

[Tulio Magno Quites Machado Filho]

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:

> As shown in some buildbot issues on aarch64 and powerpc, calling
> clone (VFORK) and waitpid (WNOHANG) does not guarantee the child
> is ready to be collected.  This patch changes the call back to 0
> as before fe05e1cb6d64 fix.
>
> This change can lead to the scenario 4.3 described in the commit,
> where the waitpid call can hang undefinitely on the call.  However
> this is also a very unlikely and also undefinied situation where
> both the caller is trying to terminate a pid before posix_spawn
> returns and the race pid reuse is triggered.  I don't see how to
> correct handle this specific situation within posix_spawn.
>
> Checked on x86_64-linux-gnu, aarch64-linux-gnu and
> powerpc64-linux-gnu.

Tested on powerpc64le too and I can't reproduce the issue anymore.

Thanks!

-- 
Tulio Magno