linux-kernel - [PATCH 2/3] hrtimer: turn newstate arg of __remove_hrtimer() into clear

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Message-ID: <20150608151135.GC23138@redhat.com>
Date:	Mon, 8 Jun 2015 17:11:35 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	umgwanakikbuti@...il.com, mingo@...e.hu, ktkhai@...allels.com,
	rostedt@...dmis.org, tglx@...utronix.de, juri.lelli@...il.com,
	pang.xunlei@...aro.org, wanpeng.li@...ux.intel.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] hrtimer: turn newstate arg of __remove_hrtimer() into
	clear_enqueued

No functional changes. Change __remove_hrtimer() to accept the boolean
and change only the HRTIMER_STATE_ENQUEUED bit. This preserves
HRTIMER_STATE_CALLBACK (which we are going to kill) automatically, the
only complication is that __run_hrtimer() should set it by hand.
---
 kernel/time/hrtimer.c |   19 +++++++++----------
 1 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 005fd44..5fceb3d 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -871,7 +871,7 @@ static int enqueue_hrtimer(struct hrtimer *timer,
  */
 static void __remove_hrtimer(struct hrtimer *timer,
 			     struct hrtimer_clock_base *base,
-			     unsigned long newstate, int reprogram)
+			     bool clear_enqueued, int reprogram)
 {
 	struct timerqueue_node *next_timer;
 	if (!(timer->state & HRTIMER_STATE_ENQUEUED))
@@ -895,7 +895,8 @@ static void __remove_hrtimer(struct hrtimer *timer,
 	if (!timerqueue_getnext(&base->active))
 		base->cpu_base->active_bases &= ~(1 << base->index);
 out:
-	timer->state = newstate;
+	if (clear_enqueued)
+		timer->state &= ~HRTIMER_STATE_ENQUEUED;
 }
 
 /*
@@ -905,7 +906,6 @@ static inline int
 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
 {
 	if (hrtimer_is_queued(timer)) {
-		unsigned long state;
 		int reprogram;
 
 		/*
@@ -920,12 +920,10 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
 		timer_stats_hrtimer_clear_start_info(timer);
 		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
 		/*
-		 * We must preserve the CALLBACK state flag here,
-		 * otherwise we could move the timer base in
-		 * switch_hrtimer_base.
+		 * This preserves the CALLBACK flag,  otherwise we could move
+		 * the timer base in switch_hrtimer_base.
 		 */
-		state = timer->state & HRTIMER_STATE_CALLBACK;
-		__remove_hrtimer(timer, base, state, reprogram);
+		__remove_hrtimer(timer, base, true, reprogram);
 		return 1;
 	}
 	return 0;
@@ -1204,7 +1202,8 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
 	WARN_ON(!irqs_disabled());
 
 	debug_deactivate(timer);
-	__remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
+	timer->state |= HRTIMER_STATE_CALLBACK;
+	__remove_hrtimer(timer, base, true, 0);
 	timer_stats_account_hrtimer(timer);
 	fn = timer->function;
 
@@ -1644,7 +1643,7 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
 		 * timer could be seen as !active and just vanish away
 		 * under us on another CPU
 		 */
-		__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
+		__remove_hrtimer(timer, old_base, false, 0);
 		timer->base = new_base;
 		/*
 		 * Enqueue the timers on the new cpu. This does not
-- 
1.5.5.1


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