linux-kernel - [PATCH] hrtimer: Replace timerqueue_getnext() uses with direct access to 'active.next'

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Date:	Thu, 9 Apr 2015 08:53:24 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Subject: [PATCH] hrtimer: Replace timerqueue_getnext() uses with direct
 access to 'active.next'


* Ingo Molnar <mingo@...nel.org> wrote:

> I'd also suggest the removal of the timerqueue_getnext() 
> obfuscation: it 'sounds' complex but in reality it's a simple 
> dereference to active.next. I think this is what triggered this 
> rather pointless maintenance of active_bases.

The patch below does this - it's more readable to me in this fashion, 
the 'next' field is already very clearly named, no need for a 
(longer!) helper function there.

I lightly tested the 3 patches with hrtimers enabled under a virtual 
machine.

Thanks,

	Ingo

---
 kernel/time/hrtimer.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Index: tip/kernel/time/hrtimer.c
===================================================================
--- tip.orig/kernel/time/hrtimer.c
+++ tip/kernel/time/hrtimer.c
@@ -451,7 +451,7 @@ static ktime_t __hrtimer_get_next_event(
 		struct timerqueue_node *next;
 		struct hrtimer *timer;
 
-		next = timerqueue_getnext(&base->active);
+		next = base->active.next;
 		if (!next)
 			continue;
 
@@ -876,7 +876,7 @@ static void __remove_hrtimer(struct hrti
 	if (!(timer->state & HRTIMER_STATE_ENQUEUED))
 		goto out;
 
-	next_timer = timerqueue_getnext(&base->active);
+	next_timer = base->active.next;
 	timerqueue_del(&base->active, &timer->node);
 	if (&timer->node == next_timer) {
 #ifdef CONFIG_HIGH_RES_TIMERS
@@ -1271,7 +1271,7 @@ retry:
 
 		basenow = ktime_add(now, base->offset);
 
-		while ((node = timerqueue_getnext(&base->active))) {
+		while ((node = base->active.next)) {
 			struct hrtimer *timer;
 
 			timer = container_of(node, struct hrtimer, node);
@@ -1438,7 +1438,7 @@ void hrtimer_run_queues(void)
 
 	for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
 		base = &cpu_base->clock_base[index];
-		if (!timerqueue_getnext(&base->active))
+		if (!base->active.next)
 			continue;
 
 		if (gettime) {
@@ -1448,7 +1448,7 @@ void hrtimer_run_queues(void)
 
 		raw_spin_lock(&cpu_base->lock);
 
-		while ((node = timerqueue_getnext(&base->active))) {
+		while ((node = base->active.next)) {
 			struct hrtimer *timer;
 
 			timer = container_of(node, struct hrtimer, node);
@@ -1631,7 +1631,7 @@ static void migrate_hrtimer_list(struct
 	struct hrtimer *timer;
 	struct timerqueue_node *node;
 
-	while ((node = timerqueue_getnext(&old_base->active))) {
+	while ((node = old_base->active.next)) {
 		timer = container_of(node, struct hrtimer, node);
 		BUG_ON(hrtimer_callback_running(timer));
 		debug_deactivate(timer);
--
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