[PATCH 5.9 637/757] sched/features: Fix !CONFIG_JUMP_LABEL case

Greg Kroah-Hartman
2020-10-27T16:37:26Z

From: Juri Lelli <juri.lelli@redhat.com>

[ Upstream commit a73f863af4ce9730795eab7097fb2102e6854365 ]

Commit:

765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds")

made sched features static for !CONFIG_SCHED_DEBUG configurations, but
overlooked the CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL cases.

For the latter echoing changes to /sys/kernel/debug/sched_features has
the nasty effect of effectively changing what sched_features reports,
but without actually changing the scheduler behaviour (since different
translation units get different sysctl_sched_features).

Fix CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL configurations by properly
restructuring ifdefs.

Fixes: 765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds")
Co-developed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Patrick Bellasi <patrick.bellasi@matbug.net>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20201013053114.160628-1-juri.lelli@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/sched/core.c | 2 +-
kernel/sched/sched.h | 13 ++++++++++---
2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2d95dc3f46444..b1e0da56abcac 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -43,7 +43,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);

DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);

-#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_JUMP_LABEL)
+#ifdef CONFIG_SCHED_DEBUG
/*
* Debugging: various feature bits
*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 28709f6b0975c..8d1ca65db3b0d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1629,7 +1629,7 @@ enum {

#undef SCHED_FEAT

-#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_JUMP_LABEL)
+#ifdef CONFIG_SCHED_DEBUG

/*
* To support run-time toggling of sched features, all the translation units
@@ -1637,6 +1637,7 @@ enum {
*/
extern const_debug unsigned int sysctl_sched_features;

+#ifdef CONFIG_JUMP_LABEL
#define SCHED_FEAT(name, enabled) \
static __always_inline bool static_branch_##name(struct static_key *key) \
{ \
@@ -1649,7 +1650,13 @@ static __always_inline bool static_branch_##name(struct static_key *key) \
extern struct static_key sched_feat_keys[__SCHED_FEAT_NR];
#define sched_feat(x) (static_branch_##x(&sched_feat_keys[__SCHED_FEAT_##x]))

-#else /* !(SCHED_DEBUG && CONFIG_JUMP_LABEL) */
+#else /* !CONFIG_JUMP_LABEL */
+
+#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
+
+#endif /* CONFIG_JUMP_LABEL */
+
+#else /* !SCHED_DEBUG */

/*
* Each translation unit has its own copy of sysctl_sched_features to allow
@@ -1665,7 +1672,7 @@ static const_debug __maybe_unused unsigned int sysctl_sched_features =

#define sched_feat(x) !!(sysctl_sched_features & (1UL << __SCHED_FEAT_##x))

-#endif /* SCHED_DEBUG && CONFIG_JUMP_LABEL */
+#endif /* SCHED_DEBUG */

extern struct static_key_false sched_numa_balancing;
extern struct static_key_false sched_schedstats;
--
2.25.1