linux-kernel - [tip:sched/core] sched/cpuset: Only offer CONFIG

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Date:   Fri, 23 Jun 2017 06:58:10 -0700
From:   tip-bot for Nicolas Pitre <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, nico@...aro.org,
        peterz@...radead.org, mingo@...nel.org, nicolas.pitre@...aro.org,
        hpa@...or.com, tglx@...utronix.de, torvalds@...ux-foundation.org
Subject: [tip:sched/core] sched/cpuset: Only offer CONFIG_CPUSETS if SMP is
 enabled

Commit-ID:  e1d4eeec5aaa28d25f249c0195b0e1d9b9feb7bd
Gitweb:     http://git.kernel.org/tip/e1d4eeec5aaa28d25f249c0195b0e1d9b9feb7bd
Author:     Nicolas Pitre <nicolas.pitre@...aro.org>
AuthorDate: Wed, 14 Jun 2017 13:19:23 -0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 23 Jun 2017 10:46:44 +0200

sched/cpuset: Only offer CONFIG_CPUSETS if SMP is enabled

Make CONFIG_CPUSETS=y 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, which shrinks the kernel a bit.

Signed-off-by: Nicolas Pitre <nico@...aro.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20170614171926.8345-2-nicolas.pitre@linaro.org
Signed-off-by: Ingo Molnar <mingo@...nel.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 1d3475f..c359038 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 62166da..7faf4b3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5451,6 +5451,8 @@ 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)
 {
@@ -5494,7 +5496,6 @@ 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,
@@ -5524,13 +5525,11 @@ 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