Hello,

I noticed some odd behaviors with idlestate.c/execute() function.

1. I wrote a sample program hello.c with infinite loop - 

    int main() {

          while(1);

    }

    #sudo ../idlestat/idlestat -o /tmp/myoutput ../temp/hello 

       

       idlestat never terminates, because there is no alarm set, hello program never terminates.

2.  If I change and invoke idlestat with below command - 

        

    #sudo ../idlestat/idlestat -o /tmp/myoutput -t 5 ../temp/hello

     

     idlestat outputs only below line and exits - 

     Total trace buffer: 153896 kB

     What is happening is the below check fails -

      if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM) {

                        return 0;

      }

      here condition is always false. Because the status variable was fetched before killing the process. So status does not contain valid signal number.

      if (waitpid(pid, &status, 0) < 0) {

                         if (errno != EINTR || !sigalrm)

                                goto again;

                        kill(pid, SIGTERM);

     }

 

     Possible Fix: call waitpid again after kill and fetch new status.

                      

3. The below check makes idlestat dependent on the hello program run -

    if (WIFEXITED(status) && !WEXITSTATUS(status)) {

      

    }

    If my program is written to return a non-zero value, the second condition will be always false. 

    So with the below program - 

    

    int main() {

           return 1;

   }    

               

    idlestat outputs only since WEXITSTATUS(status) returns nonzero value - 

    

    Total trace buffer: 153896 kB

   

In any case, it should not be allowed to run idlestat with "-t 0", since that will results in problem 1 again.

--

Thanks,

- Meraj