staging/lustre: use ktime_t for calculating elapsed time

process_param2_config() tries to print how much time has passed
across a call_usermodehelper() function, and uses struct timeval
for that.

We want to remove this structure, so this is better expressed
in terms of ktime_t and ktime_us_delta().
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/obd_config.c

@@ -1021,8 +1021,8 @@ static int process_param2_config(struct lustre_cfg *lcfg)
 		[2] = param,
 		[3] = NULL
 	};
-	struct timeval	start;
-	struct timeval	end;
+	ktime_t	start;
+	ktime_t	end;
 	int		rc;
 
 
@@ -1032,19 +1032,19 @@ static int process_param2_config(struct lustre_cfg *lcfg)
 		return -EINVAL;
 	}
 
-	do_gettimeofday(&start);
+	start = ktime_get();
 	rc = call_usermodehelper(argv[0], argv, NULL, 1);
-	do_gettimeofday(&end);
+	end = ktime_get();
 
 	if (rc < 0) {
 		CERROR(
 		       "lctl: error invoking upcall %s %s %s: rc = %d; time %ldus\n",
 		       argv[0], argv[1], argv[2], rc,
-		       cfs_timeval_sub(&end, &start, NULL));
+		       (long)ktime_us_delta(end, start));
 	} else {
 		CDEBUG(D_HA, "lctl: invoked upcall %s %s %s, time %ldus\n",
 		       argv[0], argv[1], argv[2],
-		       cfs_timeval_sub(&end, &start, NULL));
+		       (long)ktime_us_delta(end, start));
 		       rc = 0;
 	}