[tip:sched/core] sched/isolation: Provide a dynamic off-case to housekeeping_any_cpu()

[tip-bot for Frederic Weisbecker]

Commit-ID:  9f0ca2d97ef0b5e966be2cfef26c7c094ec14e41
Gitweb:     https://git.kernel.org/tip/9f0ca2d97ef0b5e966be2cfef26c7c094ec14e41
Author:     Frederic Weisbecker <frederic@xxxxxxxxxx>
AuthorDate: Fri, 27 Oct 2017 04:42:30 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 27 Oct 2017 09:55:26 +0200

sched/isolation: Provide a dynamic off-case to housekeeping_any_cpu()

housekeeping_any_cpu() doesn't handle correctly the case where
CONFIG_NO_HZ_FULL=y and no CPU is in nohz_full mode. So far no caller
needs this but let's prepare to avoid any future surprise.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Wanpeng Li <kernellwp@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1509072159-31808-4-git-send-email-frederic@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/sched/isolation.h | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index b7cfbc4..040df04 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,25 +7,20 @@
 
 #ifdef CONFIG_NO_HZ_FULL
 extern cpumask_var_t housekeeping_mask;
-
-static inline int housekeeping_any_cpu(void)
-{
-	return cpumask_any_and(housekeeping_mask, cpu_online_mask);
-}
-
 extern void __init housekeeping_init(void);
-
 #else
+static inline void housekeeping_init(void) { }
+#endif /* CONFIG_NO_HZ_FULL */
 
 static inline int housekeeping_any_cpu(void)
 {
+#ifdef CONFIG_NO_HZ_FULL
+	if (tick_nohz_full_enabled())
+		return cpumask_any_and(housekeeping_mask, cpu_online_mask);
+#endif
 	return smp_processor_id();
 }
 
-static inline void housekeeping_init(void) { }
-#endif /* CONFIG_NO_HZ_FULL */
-
-
 static inline const struct cpumask *housekeeping_cpumask(void)
 {
 #ifdef CONFIG_NO_HZ_FULL