cputime: Consolidate cputime adjustment code

task_cputime_adjusted() and thread_group_cputime_adjusted()
essentially share the same code. They just don't use the same
source:

* The first function uses the cputime in the task struct and the
previous adjusted snapshot that ensures monotonicity.

* The second adds the cputime of all tasks in the group and the
previous adjusted snapshot of the whole group from the signal
structure.

Just consolidate the common code that does the adjustment. These
functions just need to fetch the values from the appropriate
source.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 19 insertions, 4 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 */