[bug report] selftests/resctrl: Add callback to start a benchmark

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Sai Praneeth Prakhya,

The patch 7f4d257e3a2a: "selftests/resctrl: Add callback to start a
benchmark" from Jan 16, 2020, leads to the following static checker
warning:

	tools/testing/selftests/resctrl/resctrl_val.c:545 measure_vals()
	warn: 'bw_imc' unsigned <= 0

	tools/testing/selftests/resctrl/resctrl_val.c:549 measure_vals()
	warn: 'bw_resc_end' unsigned <= 0

tools/testing/selftests/resctrl/resctrl_val.c
   531  static int
   532  measure_vals(struct resctrl_val_param *param, unsigned long *bw_resc_start)
   533  {
   534          unsigned long bw_imc, bw_resc, bw_resc_end;
   535          int ret;
   536  
   537          /*
   538           * Measure memory bandwidth from resctrl and from
   539           * another source which is perf imc value or could
   540           * be something else if perf imc event is not available.
   541           * Compare the two values to validate resctrl value.
   542           * It takes 1sec to measure the data.
   543           */
   544          bw_imc = get_mem_bw_imc(param->cpu_no, param->bw_report);
   545          if (bw_imc <= 0)
                    ^^^^^^^^^^^
Unsigned.  Also the comments for get_mem_bw_imc() says that zero is
success.

   546                  return bw_imc;
   547  
   548          bw_resc_end = get_mem_bw_resctrl();
   549          if (bw_resc_end <= 0)
                    ^^^^^^^^^^^^^^^^
Unsigned

   550                  return bw_resc_end;
   551  
   552          bw_resc = (bw_resc_end - *bw_resc_start) / MB;
   553          ret = print_results_bw(param->filename, bm_pid, bw_imc, bw_resc);
   554          if (ret)
   555                  return ret;
   556  
   557          *bw_resc_start = bw_resc_end;
   558  
   559          return 0;
   560  }

regards,
dan carpenter