[tip:smp/hotplug] sched/migration: Move CPU_ONLINE into scheduler state

tip-bot for Thomas Gleixner
2016-05-06T13:07:48Z

Commit-ID: 7d97669933eb94245ec9b715753753ec5ca8f646
Gitweb: http://git.kernel.org/tip/7d97669933eb94245ec9b715753753ec5ca8f646
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Thu, 10 Mar 2016 12:54:17 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 6 May 2016 14:58:25 +0200

sched/migration: Move CPU_ONLINE into scheduler state

The alleged requirement that the migration notifier has a lower priority than
perf is completely undocumented and there is no indication at all that this is
true. perf does not even handle the CPU_ONLINE notification and perf really
has nothing to do with migration.

Move the CPU_ONLINE code into the sched_activate_cpu() state callback.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.421743581@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/sched/core.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 688e8a8..8d8d903 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5424,17 +5424,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)

switch (action & ~CPU_TASKS_FROZEN) {

- case CPU_ONLINE:
- /* Update our root-domain */
- raw_spin_lock_irqsave(&rq->lock, flags);
- if (rq->rd) {
- BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
-
- set_rq_online(rq);
- }
- raw_spin_unlock_irqrestore(&rq->lock, flags);
- break;
-
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
sched_ttwu_pending();
@@ -7090,12 +7079,34 @@ static int cpuset_cpu_inactive(unsigned int cpu)

int sched_cpu_activate(unsigned int cpu)
{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long flags;
+
set_cpu_active(cpu, true);

if (sched_smp_initialized) {
sched_domains_numa_masks_set(cpu);
cpuset_cpu_active();
}
+
+ /*
+ * Put the rq online, if not already. This happens:
+ *
+ * 1) In the early boot process, because we build the real domains
+ * after all cpus have been brought up.
+ *
+ * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
+ * domains.
+ */
+ raw_spin_lock_irqsave(&rq->lock, flags);
+ if (rq->rd) {
+ BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
+ set_rq_online(rq);
+ }
+ raw_spin_unlock_irqrestore(&rq->lock, flags);
+
+ update_max_interval();
+
return 0;
}