[LTP] [PATCH] memcg_control_test.sh:incorrect test result and a pipe issue

[Cyril Hrubis]

Hi!
> * The test result flag FAILED_CNT is handled in a sub-shell,which will
> make the test result passed even the test actually failed,update the
> scripts to not running in sub-shell.
> * Sometimes the mem_process process is killed after more than 5
> seconds,increase the sleep time to 15 sceconds.And if the mem_process
> process is killed after 5 sceconds,the pipe may blocked while writing
> it(echo m > $STATUS_PIPE;echo x > $STATUS_PIPE),then the whole LTP
> testing will hang.Adding a sub-shell to handle to pipe.
> 
> Signed-off-by: Shuang Qiu <shuang.qiu@oracle.com>
> ---
>  .../memcg/control/memcg_control_test.sh            |   15 +++++++++++----
>  1 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/testcases/kernel/controllers/memcg/control/memcg_control_test.sh b/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
> index 1d15872..668e74d 100644
> --- a/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
> +++ b/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
> @@ -64,11 +64,15 @@ test_proc_kill()
>  
>  	#Instruct the test process to start acquiring memory
>  	echo m > $STATUS_PIPE
> -	sleep 5
> +	sleep 15
>  
>  	#Check if killed
>  	ps -p $! > /dev/null 2> /dev/null
>  	if [ $? -eq 0 ]; then
> +		(sleep 30
> +		ps -p $! > /dev/null 2> /dev/null
> +		[ $? -ne 0 -a -e $STATUS_PIPE ] && cat $STATUS_PIPE && \
> +		rm -f $STATUS_PIPE) &
>  		echo m > $STATUS_PIPE
>  		echo x > $STATUS_PIPE
>  	else

This is plain wrong. Sparkling code with sleeps never solves anything
and only slows down the testrun.

What should have been done here instead is checking if the process was
killed in a loop something as twice a second with some reasonable
timeout, trying it 60 times would give it max 30 seconds to run.

> @@ -86,7 +90,8 @@ testcase_1()
>  	echo "$TOT_MEM_LIMIT" > $TST_PATH/mnt/$TST_NUM/memory.memsw.limit_in_bytes
>  
>  	mkdir sub
> -	(cd sub
> +	basedir=$PWD
> +	cd sub
>  	KILLED_CNT=0
>  	test_proc_kill
>  
> @@ -94,7 +99,8 @@ testcase_1()
>  		result $FAIL "Test #1: failed"
>  	else
>  		result $PASS "Test #1: passed"
> -	fi)
> +	fi
> +	cd $basedir
>  	rmdir sub
>  }
>  
> @@ -145,7 +151,8 @@ FAILED_CNT=0
>  TST_NUM=1
>  while [ $TST_NUM -le $TST_TOTAL ]; do
>  	mkdir $TST_PATH/mnt/$TST_NUM
> -	(cd $TST_PATH/mnt/$TST_NUM && testcase_$TST_NUM)
> +	cd $TST_PATH/mnt/$TST_NUM && testcase_$TST_NUM
> +	cd $TMP 
               ^
	       trailing whitespace
>  	rmdir $TST_PATH/mnt/$TST_NUM
>  	: $((TST_NUM += 1))
>  done

Moreover I was looking at the test recently and I would say that the
best solution would be to remove it completely, since the same function
should be covered by the memcg functional testcases. So the best bet
here would be to check that it's covered by functional tests, if not add
missing pieces to functional tests and get rid of this mess.

-- 
Cyril Hrubis
chrubis@suse.cz