3 files changed, 43 insertions, 28 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e75cab5820ab..5dafac366811 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -434,13 +434,28 @@ struct cpu_itimer {
 };
 
 /**
+ * struct cputime - snaphsot of system and user cputime
+ * @utime: time spent in user mode
+ * @stime: time spent in system mode
+ *
+ * Gathers a generic snapshot of user and system time.
+ */
+struct cputime {
+        cputime_t utime;
+        cputime_t stime;
+};
+
+/**
  * struct task_cputime - collected CPU time counts
  * @utime:              time spent in user mode, in &cputime_t units
  * @stime:              time spent in kernel mode, in &cputime_t units
  * @sum_exec_runtime:   total time spent on the CPU, in nanoseconds
  *
- * This structure groups together three kinds of CPU time that are
- * tracked for threads and thread groups.  Most things considering
+ * This is an extension of struct cputime that includes the total runtime
+ * spent by the task from the scheduler point of view.
+ *
+ * As a result, this structure groups together three kinds of CPU time
+ * that are tracked for threads and thread groups.  Most things considering
  * CPU time want to group these counts together and treat all three
  * of them in parallel.
  */
@@ -581,7 +596,7 @@ struct signal_struct {
         cputime_t gtime;
         cputime_t cgtime;
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
-        cputime_t prev_utime, prev_stime;
+        struct cputime prev_cputime;
 #endif
         unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
         unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
@@ -1340,7 +1355,7 @@ struct task_struct {
         cputime_t utime, stime, utimescaled, stimescaled;
         cputime_t gtime;
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
-        cputime_t prev_utime, prev_stime;
+        struct cputime prev_cputime;
 #endif
         unsigned long nvcsw, nivcsw; /* context switch counts */
         struct timespec start_time;             /* monotonic time */
diff --git a/kernel/fork.c b/kernel/fork.c
index 8b20ab7d3aa2..0e7cdb90476f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1222,7 +1222,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->utime = p->stime = p->gtime = 0;
         p->utimescaled = p->stimescaled = 0;
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
-        p->prev_utime = p->prev_stime = 0;
+        p->prev_cputime.utime = p->prev_cputime.stime = 0;
 #endif
 #if defined(SPLIT_RSS_COUNTING)
         memset(&p->rss_stat, 0, sizeof(p->rss_stat));
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 7dc155371b95..220fdc4db770 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -516,14 +516,18 @@ static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total)
         return (__force cputime_t) temp;
 }
 
-void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+static void cputime_adjust(struct task_cputime *curr,
+                           struct cputime *prev,
+                           cputime_t *ut, cputime_t *st)
 {
-        cputime_t rtime, utime = p->utime, total = utime + p->stime;
+        cputime_t rtime, utime, total;
 
+        utime = curr->utime;
+        total = utime + curr->stime;
         /*
          * Use CFS's precise accounting:
          */
-        rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
+        rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 
         if (total)
                 utime = scale_utime(utime, rtime, total);
@@ -533,11 +537,22 @@ void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
         /*
          * Compare with previous values, to keep monotonicity:
          */
-        p->prev_utime = max(p->prev_utime, utime);
-        p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);
+        prev->utime = max(prev->utime, utime);
+        prev->stime = max(prev->stime, rtime - prev->utime);
+
+        *ut = prev->utime;
+        *st = prev->stime;
+}
 
-        *ut = p->prev_utime;
-        *st = p->prev_stime;
+void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+        struct task_cputime cputime = {
+                .utime = p->utime,
+                .stime = p->stime,
+                .sum_exec_runtime = p->se.sum_exec_runtime,
+        };
+
+        cputime_adjust(&cputime, &p->prev_cputime, ut, st);
 }
 
 /*
@@ -545,24 +560,9 @@ void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
  */
 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 {
-        struct signal_struct *sig = p->signal;
         struct task_cputime cputime;
-        cputime_t rtime, utime, total;
 
         thread_group_cputime(p, &cputime);
-
-        total = cputime.utime + cputime.stime;
-        rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
-
-        if (total)
-                utime = scale_utime(cputime.utime, rtime, total);
-        else
-                utime = rtime;
-
-        sig->prev_utime = max(sig->prev_utime, utime);
-        sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime);
-
-        *ut = sig->prev_utime;
-        *st = sig->prev_stime;
+        cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
 }
 #endif