[PATCH 31/41] sched: Update rq clock on nohz CPU before setting fair group shares

[Frederic Weisbecker]

Because we may update the execution time (sched_group_set_shares()->
	update_cfs_shares()->reweight_entity()->update_curr()) before
reweighting the entity after updating the group shares and this requires
an uptodate version of the runqueue clock. Let's update it on the target
CPU if it runs tickless because scheduler_tick() is not there to maintain
it.

Signed-off-by: Frederic Weisbecker <fweisbec at gmail.com>
Cc: Alessio Igor Bogani <abogani at kernel.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Avi Kivity <avi at redhat.com>
Cc: Chris Metcalf <cmetcalf at tilera.com>
Cc: Christoph Lameter <cl at linux.com>
Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
Cc: Geoff Levand <geoff at infradead.org>
Cc: Gilad Ben Yossef <gilad at benyossef.com>
Cc: Hakan Akkan <hakanakkan at gmail.com>
Cc: Ingo Molnar <mingo at kernel.org>
Cc: Kevin Hilman <khilman at ti.com>
Cc: Max Krasnyansky <maxk at qualcomm.com>
Cc: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Stephen Hemminger <shemminger at vyatta.com>
Cc: Steven Rostedt <rostedt at goodmis.org>
Cc: Sven-Thorsten Dietrich <thebigcorporation at gmail.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
---
 kernel/sched/fair.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index aca16b8..3312abe 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5519,6 +5519,11 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 		se = tg->se[i];
 		/* Propagate contribution to hierarchy */
 		raw_spin_lock_irqsave(&rq->lock, flags);
+		/*
+		 * We may call update_curr() which needs an up-to-date
+		 * version of rq clock if the CPU runs tickless.
+		 */
+		update_nohz_rq_clock(rq);
 		for_each_sched_entity(se)
 			update_cfs_shares(group_cfs_rq(se));
 		raw_spin_unlock_irqrestore(&rq->lock, flags);
-- 
1.7.5.4