[PATCH] sched/cputime: correct account of irqtime

[Pingfan Liu <kernelfans@gmail.com>]

__do_softirq() may be interrupted by hardware interrupts. In this case,
irqtime_account_irq() will account the time slice as CPUTIME_SOFTIRQ by
mistake.

By passing irqtime_account_irq() an extra param about either hardirq or
softirq, irqtime_account_irq() can handle the above case.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Allen Pais <allen.lkml@gmail.com>
Cc: Romain Perier <romain.perier@gmail.com>
To: linux-kernel@vger.kernel.org
---
 include/linux/hardirq.h |  4 ++--
 include/linux/vtime.h   | 12 ++++++------
 kernel/sched/cputime.c  |  4 ++--
 kernel/softirq.c        |  6 +++---
 4 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 754f67a..56e7bb5 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -32,7 +32,7 @@ static __always_inline void rcu_irq_enter_check_tick(void)
  */
 #define __irq_enter()					\
 	do {						\
-		account_irq_enter_time(current);	\
+		account_irq_enter_time(current, true);	\
 		preempt_count_add(HARDIRQ_OFFSET);	\
 		lockdep_hardirq_enter();		\
 	} while (0)
@@ -63,7 +63,7 @@ void irq_enter_rcu(void);
 #define __irq_exit()					\
 	do {						\
 		lockdep_hardirq_exit();			\
-		account_irq_exit_time(current);		\
+		account_irq_exit_time(current, true);	\
 		preempt_count_sub(HARDIRQ_OFFSET);	\
 	} while (0)
 
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 2cdeca0..294188ae1 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -98,21 +98,21 @@ static inline void vtime_flush(struct task_struct *tsk) { }
 
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
-extern void irqtime_account_irq(struct task_struct *tsk);
+extern void irqtime_account_irq(struct task_struct *tsk, bool hardirq);
 #else
-static inline void irqtime_account_irq(struct task_struct *tsk) { }
+static inline void irqtime_account_irq(struct task_struct *tsk, bool hardirq) { }
 #endif
 
-static inline void account_irq_enter_time(struct task_struct *tsk)
+static inline void account_irq_enter_time(struct task_struct *tsk, bool hardirq)
 {
 	vtime_account_irq_enter(tsk);
-	irqtime_account_irq(tsk);
+	irqtime_account_irq(tsk, hardirq);
 }
 
-static inline void account_irq_exit_time(struct task_struct *tsk)
+static inline void account_irq_exit_time(struct task_struct *tsk, bool hardirq)
 {
 	vtime_account_irq_exit(tsk);
-	irqtime_account_irq(tsk);
+	irqtime_account_irq(tsk, hardirq);
 }
 
 #endif /* _LINUX_KERNEL_VTIME_H */
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 5a55d23..166f1d7 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -47,7 +47,7 @@ static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
  * Called before incrementing preempt_count on {soft,}irq_enter
  * and before decrementing preempt_count on {soft,}irq_exit.
  */
-void irqtime_account_irq(struct task_struct *curr)
+void irqtime_account_irq(struct task_struct *curr, bool hardirq)
 {
 	struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
 	s64 delta;
@@ -68,7 +68,7 @@ void irqtime_account_irq(struct task_struct *curr)
 	 */
 	if (hardirq_count())
 		irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
-	else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
+	else if (in_serving_softirq() && curr != this_cpu_ksoftirqd() && !hardirq)
 		irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
 }
 EXPORT_SYMBOL_GPL(irqtime_account_irq);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index bf88d7f6..da59ea39 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -270,7 +270,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 	current->flags &= ~PF_MEMALLOC;
 
 	pending = local_softirq_pending();
-	account_irq_enter_time(current);
+	account_irq_enter_time(current, false);
 
 	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
 	in_hardirq = lockdep_softirq_start();
@@ -321,7 +321,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 	}
 
 	lockdep_softirq_end(in_hardirq);
-	account_irq_exit_time(current);
+	account_irq_exit_time(current, false);
 	__local_bh_enable(SOFTIRQ_OFFSET);
 	WARN_ON_ONCE(in_interrupt());
 	current_restore_flags(old_flags, PF_MEMALLOC);
@@ -417,7 +417,7 @@ static inline void __irq_exit_rcu(void)
 #else
 	lockdep_assert_irqs_disabled();
 #endif
-	account_irq_exit_time(current);
+	account_irq_exit_time(current, true);
 	preempt_count_sub(HARDIRQ_OFFSET);
 	if (!in_interrupt() && local_softirq_pending())
 		invoke_softirq();
-- 
2.7.5