[tip:sched/core] sched/fair: Use rq_lock/unlock in online_fair_sched_group

[tip-bot for Phil Auld]

Commit-ID:  6b8fd01b21f5f2701b407a7118f236ba4c41226d
Gitweb:     https://git.kernel.org/tip/6b8fd01b21f5f2701b407a7118f236ba4c41226d
Author:     Phil Auld <pauld@xxxxxxxxxx>
AuthorDate: Thu, 1 Aug 2019 09:37:49 -0400
Committer:  Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitDate: Thu, 8 Aug 2019 09:09:31 +0200

sched/fair: Use rq_lock/unlock in online_fair_sched_group

Enabling WARN_DOUBLE_CLOCK in /sys/kernel/debug/sched_features causes
warning to fire in update_rq_clock. This seems to be caused by onlining
a new fair sched group not using the rq lock wrappers.

  [] rq->clock_update_flags & RQCF_UPDATED
  [] WARNING: CPU: 5 PID: 54385 at kernel/sched/core.c:210 update_rq_clock+0xec/0x150

  [] Call Trace:
  []  online_fair_sched_group+0x53/0x100
  []  cpu_cgroup_css_online+0x16/0x20
  []  online_css+0x1c/0x60
  []  cgroup_apply_control_enable+0x231/0x3b0
  []  cgroup_mkdir+0x41b/0x530
  []  kernfs_iop_mkdir+0x61/0xa0
  []  vfs_mkdir+0x108/0x1a0
  []  do_mkdirat+0x77/0xe0
  []  do_syscall_64+0x55/0x1d0
  []  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Using the wrappers in online_fair_sched_group instead of the raw locking
removes this warning.

Signed-off-by: Phil Auld <pauld@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190801133749.11033-1-pauld@xxxxxxxxxx
---
 kernel/sched/fair.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 19c58599e967..d9407517dae9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10281,18 +10281,18 @@ err:
 void online_fair_sched_group(struct task_group *tg)
 {
 	struct sched_entity *se;
+	struct rq_flags rf;
 	struct rq *rq;
 	int i;
 
 	for_each_possible_cpu(i) {
 		rq = cpu_rq(i);
 		se = tg->se[i];
-
-		raw_spin_lock_irq(&rq->lock);
+		rq_lock(rq, &rf);
 		update_rq_clock(rq);
 		attach_entity_cfs_rq(se);
 		sync_throttle(tg, i);
-		raw_spin_unlock_irq(&rq->lock);
+		rq_unlock(rq, &rf);
 	}
 }