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Subject: Re: [PATCH] kselftests/sched: cleanup the child processes
To:     Li Zhijian <lizhijian@cn.fujitsu.com>, peterz@infradead.org,
        shuah@kernel.org, linux-kselftest@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, Philip Li <philip.li@intel.com>,
        kernel test robot <lkp@intel.com>
References: <20210902024333.75983-1-lizhijian@cn.fujitsu.com>
From:   Chris Hyser <chris.hyser@oracle.com>
Message-ID: <282b1eaf-c506-c18c-01d7-df7bdab88fef@oracle.com>
Date:   Thu, 2 Sep 2021 07:25:21 -0400
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On 9/1/21 10:43 PM, Li Zhijian wrote:
> Previously, 'make -C sched run_tests' will block forever when it occurs
> something wrong where the *selftests framework* is waiting for its child
> processes to exit.
> 
> [root@iaas-rpma sched]# ./cs_prctl_test
> 
>   ## Create a thread/process/process group hiearchy
> Not a core sched system
> tid=74985, / tgid=74985 / pgid=74985: ffffffffffffffff
> Not a core sched system
>      tid=74986, / tgid=74986 / pgid=74985: ffffffffffffffff
> Not a core sched system
>          tid=74988, / tgid=74986 / pgid=74985: ffffffffffffffff
> Not a core sched system
>          tid=74989, / tgid=74986 / pgid=74985: ffffffffffffffff
> Not a core sched system
>          tid=74990, / tgid=74986 / pgid=74985: ffffffffffffffff
> Not a core sched system
>      tid=74987, / tgid=74987 / pgid=74985: ffffffffffffffff
> Not a core sched system
>          tid=74991, / tgid=74987 / pgid=74985: ffffffffffffffff
> Not a core sched system
>          tid=74992, / tgid=74987 / pgid=74985: ffffffffffffffff
> Not a core sched system
>          tid=74993, / tgid=74987 / pgid=74985: ffffffffffffffff
> 
> Not a core sched system
> (268) FAILED: get_cs_cookie(0) == 0
> 
>   ## Set a cookie on entire process group
> -1 = prctl(62, 1, 0, 2, 0)
> core_sched create failed -- PGID: Invalid argument
> (cs_prctl_test.c:272) -
> [root@iaas-rpma sched]# ps
>      PID TTY          TIME CMD
>     4605 pts/2    00:00:00 bash
>    74986 pts/2    00:00:00 cs_prctl_test
>    74987 pts/2    00:00:00 cs_prctl_test
>    74999 pts/2    00:00:00 ps
> 
> CC: Philip Li <philip.li@intel.com>
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> ---
>   tools/testing/selftests/sched/cs_prctl_test.c | 28 ++++++++++++-------
>   1 file changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/testing/selftests/sched/cs_prctl_test.c b/tools/testing/selftests/sched/cs_prctl_test.c
> index 63fe6521c56d..1829383715c6 100644
> --- a/tools/testing/selftests/sched/cs_prctl_test.c
> +++ b/tools/testing/selftests/sched/cs_prctl_test.c
> @@ -64,6 +64,17 @@ enum pid_type {PIDTYPE_PID = 0, PIDTYPE_TGID, PIDTYPE_PGID};
>   
>   const int THREAD_CLONE_FLAGS = CLONE_THREAD | CLONE_SIGHAND | CLONE_FS | CLONE_VM | CLONE_FILES;
>   
> +struct child_args {
> +	int num_threads;
> +	int pfd[2];
> +	int cpid;
> +	int thr_tids[MAX_THREADS];
> +};
> +
> +static struct child_args procs[MAX_PROCESSES];
> +static int num_processes = 2;
> +static int need_cleanup = 0;
> +
>   static int _prctl(int option, unsigned long arg2, unsigned long arg3, unsigned long arg4,
>   		  unsigned long arg5)
>   {
> @@ -80,8 +91,14 @@ static int _prctl(int option, unsigned long arg2, unsigned long arg3, unsigned l
>   #define handle_error(msg) __handle_error(__FILE__, __LINE__, msg)
>   static void __handle_error(char *fn, int ln, char *msg)
>   {
> +	int pidx;
>   	printf("(%s:%d) - ", fn, ln);
>   	perror(msg);
> +	if (need_cleanup) {
> +		for (pidx = 0; pidx < num_processes; ++pidx)
> +			kill(procs[pidx].cpid, 15);
> +		need_cleanup = 0;
> +	}
>   	exit(EXIT_FAILURE);
>   }
>   
> @@ -108,13 +125,6 @@ static unsigned long get_cs_cookie(int pid)
>   	return cookie;
>   }
>   
> -struct child_args {
> -	int num_threads;
> -	int pfd[2];
> -	int cpid;
> -	int thr_tids[MAX_THREADS];
> -};
> -
>   static int child_func_thread(void __attribute__((unused))*arg)
>   {
>   	while (1)
> @@ -214,10 +224,7 @@ void _validate(int line, int val, char *msg)
>   
>   int main(int argc, char *argv[])
>   {
> -	struct child_args procs[MAX_PROCESSES];
> -
>   	int keypress = 0;
> -	int num_processes = 2;
>   	int num_threads = 3;
>   	int delay = 0;
>   	int res = 0;
> @@ -264,6 +271,7 @@ int main(int argc, char *argv[])
>   
>   	printf("\n## Create a thread/process/process group hiearchy\n");
>   	create_processes(num_processes, num_threads, procs);
> +	need_cleanup = 1;
>   	disp_processes(num_processes, procs);
>   	validate(get_cs_cookie(0) == 0);
>   

Reviewed-by: Chris Hyser <chris.hyser@oracle.com>