[LTP] [PATCH] cpuacct_task: exit cleanly on SIGVTALRM

[Stanislav Kholmanskikh]

Hi!

On 08/31/2016 04:34 PM, Cyril Hrubis wrote:
> Hi!
>> We don't handle the SIGVTALRM signal in cpuacct_task,
>> so the process gets terminated, and it makes cpuacct.sh generate
>> a "Virtual timer expired" message for each cpuacct_task process.
>>
>> In my opinion, these messages have no real value, and there is no
>> need in keeping them in the output.
> 
> I was just too lazy to install the signal handler in this case given
> that the default action for the signal is to terminate the process...
> 
>> Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
>> ---
>>  .../kernel/controllers/cpuacct/cpuacct_task.c      |   23 +++++++++++++++++++-
>>  1 files changed, 22 insertions(+), 1 deletions(-)
>>
>> diff --git a/testcases/kernel/controllers/cpuacct/cpuacct_task.c b/testcases/kernel/controllers/cpuacct/cpuacct_task.c
>> index 0ca01d1..94aa4e6 100644
>> --- a/testcases/kernel/controllers/cpuacct/cpuacct_task.c
>> +++ b/testcases/kernel/controllers/cpuacct/cpuacct_task.c
>> @@ -25,11 +25,21 @@
>>  #include <sys/time.h>
>>  #include <sys/types.h>
>>  #include <unistd.h>
>> +#include <signal.h>
>>  #include <stdlib.h>
>> +#include <string.h>
>> +
>> +static volatile int got_signal;
>> +
>> +static void sig_handler(int signo)
>> +{
>> +	got_signal = 1;
>> +}
> 
> We can as well do _exit(0); here. Then we don't have to add the global
> variable and the main loop will stay as for (;;);

Ok

> 
>>  int main(int argc, char **argv)
>>  {
>>  	FILE *f;
>> +	struct sigaction sa;
>>  
>>  	if (argc != 2) {
>>  		fprintf(stderr, "Usage: %s /cgroup/.../tasks\n", argv[0]);
>> @@ -44,9 +54,20 @@ int main(int argc, char **argv)
>>  
>>  	fprintf(f, "%i\n", getpid());
>>  	fclose(f);
>> +
>> +	memset(&sa, 0, sizeof(sa));
>> +	sigemptyset(&sa.sa_mask);
>> +	sa.sa_handler = sig_handler;
>> +
>> +	if (sigaction(SIGVTALRM, &sa, NULL)) {
>> +		perror("sigaction failed");
>> +		return 1;
>> +	}
> 
> I would just use simpler signal(SIGVTALRM, sig_handler); here.

I tend to use sigaction() everywhere, since the man page for signal()
gives preference to sigaction() for the general case.

> 
>>  	struct itimerval it = {.it_value = {.tv_sec = 0, .tv_usec = 10000}};
>>  
>>  	setitimer(ITIMER_VIRTUAL, &it, NULL);
>> -	for (;;);
>> +	while (!got_signal)
>> +		;
>>  	return 0;
>>  }
> 
> Other than that it's fine.
>