linux-kernel - [tip:sched/core] housekeeping: Use its own static key

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Date:   Tue, 24 Oct 2017 07:50:56 -0700
From:   tip-bot for Frederic Weisbecker <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, peterz@...radead.org, cmetcalf@...lanox.com,
        paulmck@...ux.vnet.ibm.com, cl@...ux.com, tglx@...utronix.de,
        lcapitulino@...hat.com, mingo@...nel.org, efault@....de,
        kernellwp@...il.com, torvalds@...ux-foundation.org,
        linux-kernel@...r.kernel.org, riel@...hat.com, frederic@...nel.org
Subject: [tip:sched/core] housekeeping: Use its own static key

Commit-ID:  a8269e3baec363b58348208719f08c9c313b1bdf
Gitweb:     https://git.kernel.org/tip/a8269e3baec363b58348208719f08c9c313b1bdf
Author:     Frederic Weisbecker <frederic@...nel.org>
AuthorDate: Tue, 24 Oct 2017 15:06:54 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 24 Oct 2017 15:20:14 +0200

housekeeping: Use its own static key

Housekeeping code still depends on nohz_full static key. Since we want
to decouple housekeeping from nohz, let's create a housekeeping own static
key. It's mostly relevant for calls to is_housekeeping_cpu() from the
scheduler.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
Cc: Mike Galbraith <efault@....de>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <kernellwp@...il.com>
Link: http://lkml.kernel.org/r/1508850421-10058-6-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/housekeeping.h |  3 ++-
 kernel/housekeeping.c        | 14 +++++++++-----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/housekeeping.h b/include/linux/housekeeping.h
index 31a1401..cbe8d63 100644
--- a/include/linux/housekeeping.h
+++ b/include/linux/housekeeping.h
@@ -6,6 +6,7 @@
 #include <linux/tick.h>
 
 #ifdef CONFIG_NO_HZ_FULL
+DECLARE_STATIC_KEY_FALSE(housekeeping_overriden);
 extern int housekeeping_any_cpu(void);
 extern const struct cpumask *housekeeping_cpumask(void);
 extern void housekeeping_affine(struct task_struct *t);
@@ -31,7 +32,7 @@ static inline void housekeeping_init(void) { }
 static inline bool is_housekeeping_cpu(int cpu)
 {
 #ifdef CONFIG_NO_HZ_FULL
-	if (tick_nohz_full_enabled())
+	if (static_branch_unlikely(&housekeeping_overriden))
 		return housekeeping_test_cpu(cpu);
 #endif
 	return true;
diff --git a/kernel/housekeeping.c b/kernel/housekeeping.c
index 0e70dc8..272c344 100644
--- a/kernel/housekeeping.c
+++ b/kernel/housekeeping.c
@@ -10,12 +10,15 @@
 #include <linux/tick.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/static_key.h>
 
+DEFINE_STATIC_KEY_FALSE(housekeeping_overriden);
+EXPORT_SYMBOL_GPL(housekeeping_overriden);
 static cpumask_var_t housekeeping_mask;
 
 int housekeeping_any_cpu(void)
 {
-	if (tick_nohz_full_enabled())
+	if (static_branch_unlikely(&housekeeping_overriden))
 		return cpumask_any_and(housekeeping_mask, cpu_online_mask);
 
 	return smp_processor_id();
@@ -23,7 +26,7 @@ int housekeeping_any_cpu(void)
 
 const struct cpumask *housekeeping_cpumask(void)
 {
-	if (tick_nohz_full_enabled())
+	if (static_branch_unlikely(&housekeeping_overriden))
 		return housekeeping_mask;
 
 	return cpu_possible_mask;
@@ -31,19 +34,18 @@ const struct cpumask *housekeeping_cpumask(void)
 
 void housekeeping_affine(struct task_struct *t)
 {
-	if (tick_nohz_full_enabled())
+	if (static_branch_unlikely(&housekeeping_overriden))
 		set_cpus_allowed_ptr(t, housekeeping_mask);
 }
 
 bool housekeeping_test_cpu(int cpu)
 {
-	if (tick_nohz_full_enabled())
+	if (static_branch_unlikely(&housekeeping_overriden))
 		return cpumask_test_cpu(cpu, housekeeping_mask);
 
 	return true;
 }
 
-
 void __init housekeeping_init(void)
 {
 	if (!tick_nohz_full_enabled())
@@ -59,6 +61,8 @@ void __init housekeeping_init(void)
 	cpumask_andnot(housekeeping_mask,
 		       cpu_possible_mask, tick_nohz_full_mask);
 
+	static_branch_enable(&housekeeping_overriden);
+
 	/* We need at least one CPU to handle housekeeping work */
 	WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
 }