cputime: Avoid multiplication overflow on utime scaling

[deliverable/linux.git] / kernel / sched / cputime.c

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 293b202fcf79e1ba577d0672598ba59f4e8ebf56..825a956ccdb6eea475cf141838dd0b5d396d0d23 100644 (file)
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -509,11 +509,11 @@ EXPORT_SYMBOL_GPL(vtime_account);
 # define nsecs_to_cputime(__nsecs)     nsecs_to_jiffies(__nsecs)
 #endif
 
-static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total)
+static cputime_t scale_stime(cputime_t stime, cputime_t rtime, cputime_t total)
 {
        u64 temp = (__force u64) rtime;
 
-       temp *= (__force u64) utime;
+       temp *= (__force u64) stime;
 
        if (sizeof(cputime_t) == 4)
                temp = div_u64(temp, (__force u32) total);
@@ -531,10 +531,10 @@ static void cputime_adjust(struct task_cputime *curr,
                           struct cputime *prev,
                           cputime_t *ut, cputime_t *st)
 {
-       cputime_t rtime, utime, total;
+       cputime_t rtime, stime, total;
 
-       utime = curr->utime;
-       total = utime + curr->stime;
+       stime = curr->stime;
+       total = stime + curr->utime;
 
        /*
         * Tick based cputime accounting depend on random scheduling
@@ -549,17 +549,17 @@ static void cputime_adjust(struct task_cputime *curr,
        rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 
        if (total)
-               utime = scale_utime(utime, rtime, total);
+               stime = scale_stime(stime, rtime, total);
        else
-               utime = rtime;
+               stime = rtime;
 
        /*
         * If the tick based count grows faster than the scheduler one,
         * the result of the scaling may go backward.
         * Let's enforce monotonicity.
         */
-       prev->utime = max(prev->utime, utime);
-       prev->stime = max(prev->stime, rtime - prev->utime);
+       prev->stime = max(prev->stime, stime);
+       prev->utime = max(prev->utime, rtime - prev->stime);
 
        *ut = prev->utime;
        *st = prev->stime;