linux-kernel - [PATCH 1/7] sched/topology: Adding function partition_sched_domains

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Message-Id: <1502918443-30169-2-git-send-email-mathieu.poirier@linaro.org>
Date:   Wed, 16 Aug 2017 15:20:37 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     mingo@...hat.com, peterz@...radead.org
Cc:     tj@...nel.org, vbabka@...e.cz, lizefan@...wei.com,
        akpm@...ux-foundation.org, weiyongjun1@...wei.com,
        juri.lelli@....com, rostedt@...dmis.org, claudio@...dence.eu.com,
        luca.abeni@...tannapisa.it, bristot@...hat.com,
        linux-kernel@...r.kernel.org, mathieu.poirier@...aro.org
Subject: [PATCH 1/7] sched/topology: Adding function partition_sched_domains_locked()

Introducing function partition_sched_domains_locked() by taking
the mutex locking code out of the original function.  That way
the work done by partition_sched_domains_locked() can be reused
without dropping the mutex lock.

This patch doesn't change the functionality provided by the
original code.

Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
 include/linux/sched/topology.h |  9 +++++++++
 kernel/sched/topology.c        | 17 +++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 7d065abc7a47..59b568079e05 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -161,6 +161,9 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
 	return to_cpumask(sd->span);
 }
 
+extern void partition_sched_domains_locked(int ndoms_new,
+					   cpumask_var_t doms_new[],
+					   struct sched_domain_attr *dattr_new);
 extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 				    struct sched_domain_attr *dattr_new);
 
@@ -206,6 +209,12 @@ extern void set_sched_topology(struct sched_domain_topology_level *tl);
 struct sched_domain_attr;
 
 static inline void
+partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
+			       struct sched_domain_attr *dattr_new)
+{
+}
+
+static inline void
 partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 			struct sched_domain_attr *dattr_new)
 {
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 9b4f2701ba3c..58133f2ce889 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1840,15 +1840,15 @@ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
  * ndoms_new == 0 is a special case for destroying existing domains,
  * and it will not create the default domain.
  *
- * Call with hotplug lock held
+ * Call with hotplug lock and sched_domains_mutex held
  */
-void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
-			     struct sched_domain_attr *dattr_new)
+void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
+				    struct sched_domain_attr *dattr_new)
 {
 	int i, j, n;
 	int new_topology;
 
-	mutex_lock(&sched_domains_mutex);
+	lockdep_assert_held(&sched_domains_mutex);
 
 	/* Always unregister in case we don't destroy any domains: */
 	unregister_sched_domain_sysctl();
@@ -1902,7 +1902,16 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 	ndoms_cur = ndoms_new;
 
 	register_sched_domain_sysctl();
+}
 
+/*
+ * Call with hotplug lock held
+ */
+void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
+			     struct sched_domain_attr *dattr_new)
+{
+	mutex_lock(&sched_domains_mutex);
+	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
 	mutex_unlock(&sched_domains_mutex);
 }
 
-- 
2.7.4