[LTP] [PATCH] cgroup: fix mount errors on cgroup subsys

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> ---
>  .../controllers/cgroup/cgroup_regression_test.sh   | 46 +++++++++++++++++++++-
>  1 file changed, 44 insertions(+), 2 deletions(-)
> 
> diff --git a/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh b/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
> index 30d0dbf..971243f 100755
> --- a/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
> +++ b/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
> @@ -181,10 +181,17 @@ test_3()
>  		return
>  	fi
>  
> +	local cpu=cpu
> +
> +	# For rhel7.3 or later, cpu is always binding with cpuacct subsys
> +	if grep -w cpu /proc/mounts ; then
> +		cpu=$(basename $(grep -w cpu /proc/mounts | cut -d ' ' -f 2))
> +	fi
> +
>  	# Run the test for 30 secs
> -	mount -t cgroup -o cpu xxx cgroup/
> +	mount -t cgroup -o $cpu xxx cgroup/
>  	if [ $? -ne 0 ]; then
> -		tst_resm TFAIL "Failed to mount cpu subsys"
> +		tst_resm TFAIL "Failed to mount $cpu subsys"
>  		failed=1
>  		return
>  	fi

Why can't we mount the cgroup only when it's not mounted yet and
use the path it's mounted on otherwise? We do that for the functional
tetscases already.

And I do not think that umounting system cgroups is a good idea either.
I would say that the test should use whatever is mounted on the system
and if that is not possible I would rather produce TCONF than fiddle
with umounting cgroups from the standard system path.

-- 
Cyril Hrubis
chrubis@suse.cz