[LTP] [PATCH] cpuset_regression_test: Fix for already existing cpusets

[Joerg Vehlow <lkml@jv-coder.de>]

Hi,

a ping for this patch? Is something like that (workaround environment 
issues) not wanted in ltp?

Greets
J?rg

On 11/15/2019 11:10 AM, Joerg Vehlow wrote:
> From: Joerg Vehlow <joerg.vehlow@aox-tech.de>
>
> If there are already cpusets defined on the system, that use cpu 0-1,
> the test fails, because it tries to exclusively use cpu 0-1 for the
> testcase.
>
> The fix sets the cpuset for all cgroups to 0 and disables exclusive
> cpu usage for the duration of the test and restores it on cleanup.
> For the test only cpu 1 is set as exclusive. This is enough to
> trigger the bug this regression test was designed for.
> This was tested by reverting the commit mentioned in the testcase.
>
> Signed-off-by: Joerg Vehlow <joerg.vehlow@aox-tech.de>
> ---
>   .../cpuset/cpuset_regression_test.sh          | 58 +++++++++++++++++--
>   1 file changed, 54 insertions(+), 4 deletions(-)
>
> diff --git a/testcases/kernel/controllers/cpuset/cpuset_regression_test.sh b/testcases/kernel/controllers/cpuset/cpuset_regression_test.sh
> index dccfd91cd..ed5e30f2a 100755
> --- a/testcases/kernel/controllers/cpuset/cpuset_regression_test.sh
> +++ b/testcases/kernel/controllers/cpuset/cpuset_regression_test.sh
> @@ -26,6 +26,49 @@ TCID=cpuset_regression_test
>   TST_TOTAL=1
>   . test.sh
>   
> +# cpuset_backup_and_update <backup_dir> <what> <value>
> +# Create backup of the values of a specific file (<what>)
> +# in all cpuset groups and set the value to <value>
> +# The backup is written to <backup_dir> in the same structure
> +# as in the cpuset filesystem
> +cpuset_backup_and_update()
> +{
> +	local backup_dir=$1
> +	local what=$2
> +	local value=$3
> +	local old_dir=$(pwd)
> +
> +	cd ${root_cpuset_dir}
> +	find . -mindepth 2 -name ${what} -print0 |
> +	while IFS= read -r -d '' file; do
> +		tst_resm TINFO "Backup ${file} ($(cat "${file}"))"
> +		mkdir -p "$(dirname "${backup_dir}/${file}")"
> +		cat "${file}" > "${backup_dir}/${file}"
> +		echo "${value}" > "${file}"
> +	done
> +
> +	cd ${old_dir}
> +}
> +
> +# cpuset_restore <backup_dir> <what>
> +# Restores the value of a file (<what>) in all cpuset
> +# groups from the backup created by cpuset_backup_and_update
> +cpuset_restore()
> +{
> +	local backup_dir=$1
> +	local what=$2
> +	local old_dir=$(pwd)
> +
> +	cd ${backup_dir}
> +	find . -mindepth 2 -name ${what} -print0 |
> +	while IFS= read -r -d '' file; do
> +		tst_resm TINFO "Restore ${file} ($(cat "${file}"))"
> +		cat "${file}" > "${root_cpuset_dir}/${file}"
> +	done
> +
> +	cd ${old_dir}
> +}
> +
>   setup()
>   {
>   	tst_require_root
> @@ -69,6 +112,10 @@ setup()
>   			       "do not exist."
>   	fi
>   
> +	mkdir cpuset_backup
> +	cpuset_backup_and_update "$(pwd)/cpuset_backup" ${cpu_exclusive} 0
> +	cpuset_backup_and_update "$(pwd)/cpuset_backup" cpuset.cpus 0
> +
>   	cpu_exclusive_value=$(cat ${root_cpuset_dir}/${cpu_exclusive})
>   	if [ "${cpu_exclusive_value}" != "1" ];then
>   		echo 1 > ${root_cpuset_dir}/${cpu_exclusive}
> @@ -86,6 +133,9 @@ cleanup()
>   		rmdir ${root_cpuset_dir}/testdir
>   	fi
>   
> +	cpuset_restore "$(pwd)/cpuset_backup" cpuset.cpus
> +	cpuset_restore "$(pwd)/cpuset_backup" ${cpu_exclusive}
> +
>   	if [ "$cpu_exclusive_value" != 1 ]; then
>   		# Need to flush, or may be output:
>   		# "write error: Device or resource busy"
> @@ -129,15 +179,15 @@ cpuset_test()
>   	fi
>   
>   	# ${cpus} is empty at the begin, that maybe make the system *crash*.
> -	echo 0-1 > ${root_cpuset_dir}/testdir/${cpus}
> +	echo 1 > ${root_cpuset_dir}/testdir/${cpus}
>   	if [ $? -ne 0 ]; then
> -		tst_brkm TFAIL "'echo 0-1 >" \
> +		tst_brkm TFAIL "'echo 1 >" \
>   			       "${root_cpuset_dir}/testdir/${cpus}' failed"
>   	fi
>   
>   	local cpus_value=$(cat ${root_cpuset_dir}/testdir/${cpus})
> -	if [ "${cpus_value}" != "0-1" ]; then
> -		tst_brkm TFAIL "${cpus} is '${cpus_value}', expected '0-1'"
> +	if [ "${cpus_value}" != "1" ]; then
> +		tst_brkm TFAIL "${cpus} is '${cpus_value}', expected '1'"
>   	fi
>   
>   	tst_resm TPASS "Bug is not reproduced"