From a7e1a9e3af71b45ecae2dae35851f238117b317d Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Sat, 8 Sep 2012 16:14:02 +0200
Subject: vtime: Consolidate system/idle context detection

Move the code that finds out to which context we account the
cputime into generic layer.

Archs that consider the whole time spent in the idle task as idle
time (ia64, powerpc) can rely on the generic vtime_account()
and implement vtime_account_system() and vtime_account_idle(),
letting the generic code to decide when to call which API.

Archs that have their own meaning of idle time, such as s390
that only considers the time spent in CPU low power mode as idle
time, can just override vtime_account().

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 kernel/sched/cputime.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'kernel/sched')

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 53f5b12f282..81b763ba58a 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -432,6 +432,32 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 	*ut = cputime.utime;
 	*st = cputime.stime;
 }
+
+/*
+ * Archs that account the whole time spent in the idle task
+ * (outside irq) as idle time can rely on this and just implement
+ * vtime_account_system() and vtime_account_idle(). Archs that
+ * have other meaning of the idle time (s390 only includes the
+ * time spent by the CPU when it's in low power mode) must override
+ * vtime_account().
+ */
+#ifndef __ARCH_HAS_VTIME_ACCOUNT
+void vtime_account(struct task_struct *tsk)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (in_interrupt() || !is_idle_task(tsk))
+		vtime_account_system(tsk);
+	else
+		vtime_account_idle(tsk);
+
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(vtime_account);
+#endif /* __ARCH_HAS_VTIME_ACCOUNT */
+
 #else
 
 #ifndef nsecs_to_cputime
-- 
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