cputime: Separate irqtime accounting from generic vtime

vtime_account() doesn't have the same role in
CONFIG_VIRT_CPU_ACCOUNTING and CONFIG_IRQ_TIME_ACCOUNTING.

In the first case it handles time accounting in any context. In
the second case it only handles irq time accounting.

So when vtime_account() is called from outside vtime_account_irq_*()
this call is pointless to CONFIG_IRQ_TIME_ACCOUNTING.

To fix the confusion, change vtime_account() to irqtime_account_irq()
in CONFIG_IRQ_TIME_ACCOUNTING. This way we ensure future account_vtime()
calls won't waste useless cycles in the irqtime APIs.

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

include/linux/vtime.h

@@ -8,17 +8,18 @@ extern void vtime_task_switch(struct task_struct *prev);
 extern void __vtime_account_system(struct task_struct *tsk);
 extern void vtime_account_system(struct task_struct *tsk);
 extern void __vtime_account_idle(struct task_struct *tsk);
+extern void vtime_account(struct task_struct *tsk);
 #else
 static inline void vtime_task_switch(struct task_struct *prev) { }
+static inline void __vtime_account_system(struct task_struct *tsk) { }
 static inline void vtime_account_system(struct task_struct *tsk) { }
+static inline void vtime_account(struct task_struct *tsk) { }
 #endif
 
-#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
-static inline void vtime_account(struct task_struct *tsk)
-{
-}
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+extern void irqtime_account_irq(struct task_struct *tsk);
 #else
-extern void vtime_account(struct task_struct *tsk);
+static inline void irqtime_account_irq(struct task_struct *tsk) { }
 #endif
 
 static inline void vtime_account_irq_enter(struct task_struct *tsk)
@@ -33,17 +34,14 @@ static inline void vtime_account_irq_enter(struct task_struct *tsk)
 	 * the idle time is flushed on hardirq time already.
 	 */
 	vtime_account(tsk);
+	irqtime_account_irq(tsk);
 }
 
 static inline void vtime_account_irq_exit(struct task_struct *tsk)
 {
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	/* On hard|softirq exit we always account to hard|softirq cputime */
 	__vtime_account_system(tsk);
-#endif
-#ifdef CONFIG_IRQ_TIME_ACCOUNTING
-	vtime_account(tsk);
-#endif
+	irqtime_account_irq(tsk);
 }
 
 #endif /* _LINUX_KERNEL_VTIME_H */

kernel/sched/cputime.c

@@ -43,7 +43,7 @@ DEFINE_PER_CPU(seqcount_t, irq_time_seq);
  * Called before incrementing preempt_count on {soft,}irq_enter
  * and before decrementing preempt_count on {soft,}irq_exit.
  */
-void vtime_account(struct task_struct *curr)
+void irqtime_account_irq(struct task_struct *curr)
 {
 	unsigned long flags;
 	s64 delta;
@@ -73,7 +73,7 @@ void vtime_account(struct task_struct *curr)
 	irq_time_write_end();
 	local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(vtime_account);
+EXPORT_SYMBOL_GPL(irqtime_account_irq);
 
 static int irqtime_account_hi_update(void)
 {