[RFC PATCH 03/12] housekeeping: Provide a dynamic off-case to housekeeping_any_cpu()

From: Frederic Weisbecker
Date: Tue Aug 22 2017 - 21:54:11 EST


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 <fweisbec@xxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Wanpeng Li <kernellwp@xxxxxxxxx>
Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
---
include/linux/housekeeping.h | 21 ++++++++-------------
1 file changed, 8 insertions(+), 13 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
@@ -7,24 +7,19 @@

#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 int housekeeping_any_cpu(void)
-{
- return smp_processor_id();
-}
-
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 const struct cpumask *housekeeping_cpumask(void)
{
--
2.7.4