linux-kernel - [PATCH 1/4] cpuset/sched: cpuset makes sense for SMP only

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Message-Id: <20170614171926.8345-2-nicolas.pitre@linaro.org>
Date:   Wed, 14 Jun 2017 13:19:23 -0400
From:   Nicolas Pitre <nicolas.pitre@...aro.org>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] cpuset/sched: cpuset makes sense for SMP only

Make CONFIG_CPUSETS depend on SMP as this feature makes no sense
on UP. This allows for configuring out cpuset_cpumask_can_shrink()
and task_can_attach() entirely.

Signed-off-by: Nicolas Pitre <nico@...aro.org>
---
 init/Kconfig        | 1 +
 kernel/sched/core.c | 7 +++----
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 4ef946b466..b9aed60cac 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1156,6 +1156,7 @@ config CGROUP_HUGETLB
 
 config CPUSETS
 	bool "Cpuset controller"
+	depends on SMP
 	help
 	  This option will let you create and manage CPUSETs which
 	  allow dynamically partitioning a system into sets of CPUs and
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2a2c9c4fb3..94fa712791 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5463,6 +5463,8 @@ void init_idle(struct task_struct *idle, int cpu)
 #endif
 }
 
+#ifdef CONFIG_SMP
+
 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
 			      const struct cpumask *trial)
 {
@@ -5506,7 +5508,6 @@ int task_can_attach(struct task_struct *p,
 		goto out;
 	}
 
-#ifdef CONFIG_SMP
 	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
 					      cs_cpus_allowed)) {
 		unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
@@ -5536,13 +5537,11 @@ int task_can_attach(struct task_struct *p,
 		rcu_read_unlock_sched();
 
 	}
-#endif
+
 out:
 	return ret;
 }
 
-#ifdef CONFIG_SMP
-
 bool sched_smp_initialized __read_mostly;
 
 #ifdef CONFIG_NUMA_BALANCING
-- 
2.9.4