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

[tip-bot for Frederic Weisbecker <tipbot@zytor.com>]

Commit-ID:  da65e6d81cc6b51cbcefddca9f69d43e7da7b1c1
Gitweb:     https://git.kernel.org/tip/da65e6d81cc6b51cbcefddca9f69d43e7da7b1c1
Author:     Frederic Weisbecker <frederic@kernel.org>
AuthorDate: Tue, 24 Oct 2017 15:06:52 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Oct 2017 15:20:13 +0200

housekeeping: 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@kernel.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1508850421-10058-4-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/housekeeping.h | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/include/linux/housekeeping.h b/include/linux/housekeeping.h
index 3d6a8e6..64d0ee5 100644
--- a/include/linux/housekeeping.h
+++ b/include/linux/housekeeping.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