In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE to delay
cputime accounting to the tick, let's provide APIs to account system
time to precise contexts: hardirq, softirq, pure system, ...

Inspired-by: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Heiko Carstens <heiko.carst...@de.ibm.com>
Cc: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Tony Luck <tony.l...@intel.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Rik van Riel <r...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Stanislaw Gruszka <sgrus...@redhat.com>
Cc: Wanpeng Li <wanpeng...@hotmail.com>
Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
---
 include/linux/kernel_stat.h |  4 ++++
 kernel/sched/cputime.c      | 19 ++++++++++++++-----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 00f7768..544aa86 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -80,10 +80,14 @@ static inline unsigned int kstat_cpu_irqs_sum(unsigned int 
cpu)
 
 extern void account_user_time(struct task_struct *, cputime_t);
 extern void account_system_time(struct task_struct *, int, cputime_t);
+extern void account_system_index_time(struct task_struct *, cputime_t,
+                                     enum cpu_usage_stat);
 extern void account_steal_time(cputime_t);
 extern void account_idle_time(cputime_t);
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+extern void account_system_index_scaled(struct task_struct *, cputime_t,
+                                       cputime_t, enum cpu_usage_stat);
 static inline void account_process_tick(struct task_struct *tsk, int user)
 {
        vtime_account_user(tsk);
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 7700a9c..0e6ea60 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -176,8 +176,8 @@ static void account_guest_time(struct task_struct *p, 
cputime_t cputime)
  * @cputime: the cpu time spent in kernel space since the last update
  * @index: pointer to cpustat field that has to be updated
  */
-static inline
-void __account_system_time(struct task_struct *p, cputime_t cputime, int index)
+void account_system_index_time(struct task_struct *p,
+                              cputime_t cputime, enum cpu_usage_stat index)
 {
        /* Add system time to process. */
        p->stime += cputime;
@@ -190,6 +190,15 @@ void __account_system_time(struct task_struct *p, 
cputime_t cputime, int index)
        acct_account_cputime(p);
 }
 
+#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
+void account_system_index_scaled(struct task_struct *p, cputime_t cputime,
+                                cputime_t scaled, enum cpu_usage_stat index)
+{
+       p->stimescaled += scaled;
+       account_system_index_time(p, cputime, index);
+}
+#endif
+
 /*
  * Account system cpu time to a process.
  * @p: the process that the cpu time gets accounted to
@@ -213,7 +222,7 @@ void account_system_time(struct task_struct *p, int 
hardirq_offset,
        else
                index = CPUTIME_SYSTEM;
 
-       __account_system_time(p, cputime, index);
+       account_system_index_time(p, cputime, index);
 }
 
 /*
@@ -400,7 +409,7 @@ static void irqtime_account_process_tick(struct task_struct 
*p, int user_tick,
                 * So, we have to handle it separately here.
                 * Also, p->stime needs to be updated for ksoftirqd.
                 */
-               __account_system_time(p, cputime, CPUTIME_SOFTIRQ);
+               account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
        } else if (user_tick) {
                account_user_time(p, cputime);
        } else if (p == rq->idle) {
@@ -408,7 +417,7 @@ static void irqtime_account_process_tick(struct task_struct 
*p, int user_tick,
        } else if (p->flags & PF_VCPU) { /* System time or guest time */
                account_guest_time(p, cputime);
        } else {
-               __account_system_time(p, cputime, CPUTIME_SYSTEM);
+               account_system_index_time(p, cputime, CPUTIME_SYSTEM);
        }
 }
 
-- 
2.7.4

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