[LTP] [PATCH v2] test_children_cleanup.sh: Fix race condition

[Cyril Hrubis]

Hi!
> Processes can stay alive for a short while even after receiving SIGKILL.
> Give the child in subprocess cleanup libtest up to 5 seconds to fully exit
> or change state to zombie before reporting that it was left behind.
> 
> Signed-off-by: Martin Doucha <mdoucha@suse.cz>
> ---
> 
> Changes since v1: Report success even if the child gets stuck in zombie state
> 
>  lib/newlib_tests/test_children_cleanup.sh | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/newlib_tests/test_children_cleanup.sh b/lib/newlib_tests/test_children_cleanup.sh
> index 4b4e8b2f0..23408c1bc 100755
> --- a/lib/newlib_tests/test_children_cleanup.sh
> +++ b/lib/newlib_tests/test_children_cleanup.sh
> @@ -10,10 +10,21 @@ rm "$TMPFILE"
>  if [ "x$CHILD_PID" = "x" ]; then
>  	echo "TFAIL: Child process was not created"
>  	exit 1
> -elif ! kill -s 0 $CHILD_PID &>/dev/null; then
> -	echo "TPASS: Child process was cleaned up"
> -	exit 0
> -else
> -	echo "TFAIL: Child process was left behind"
> -	exit 1
>  fi
> +
> +# The child process can stay alive for a short while even after receiving
> +# SIGKILL, especially if the system is under heavy load. Wait up to 5 seconds
> +# for it to fully exit.
> +for i in `seq 6`; do
> +	CHILD_STATE=`sed -ne 's/^State:\s*\([A-Z]\).*$/\1/p' "/proc/$CHILD_PID/status" 2>/dev/null`
> +
> +	if [ ! -e "/proc/$CHILD_PID" ] || [ "x$CHILD_STATE" = "xZ" ]; then

As long as we have the variable inside the quotes there is no point in
adding the 'x'.

Other than that:

Reviewed-by: Cyril Hrubis <chrubis@suse.cz>

> +		echo "TPASS: Child process was cleaned up"
> +		exit 0
> +	fi
> +
> +	sleep 1
> +done
> +
> +echo "TFAIL: Child process was left behind"
> +exit 1

-- 
Cyril Hrubis
chrubis@suse.cz