- cputime_advance(&prev->stime, stime);
- cputime_advance(&prev->utime, utime);
+ stime = scale_stime((__force u64)stime, (__force u64)rtime,
+ (__force u64)(stime + utime));
+
+ /*
+ * Make sure stime doesn't go backwards; this preserves monotonicity
+ * for utime because rtime is monotonic.
+ *
+ * utime_i+1 = rtime_i+1 - stime_i
+ * = rtime_i+1 - (rtime_i - utime_i)
+ * = (rtime_i+1 - rtime_i) + utime_i
+ * >= utime_i
+ */
+ if (stime < prev->stime)
+ stime = prev->stime;
+ utime = rtime - stime;
+
+ /*
+ * Make sure utime doesn't go backwards; this still preserves
+ * monotonicity for stime, analogous argument to above.
+ */
+ if (utime < prev->utime) {
+ utime = prev->utime;
+ stime = rtime - utime;
+ }