[PATCH 5.4 321/408] sched/features: Fix !CONFIG_JUMP_LABEL case

Greg Kroah-Hartman
2020-10-27T14:52:28Z

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 79ce22de44095..4511532b08b84 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -36,7 +36,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_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 9f2a9e34a78d5..3e7590813844f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1568,7 +1568,7 @@ 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
@@ -1576,6 +1576,7 @@ 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) \
{ \
@@ -1588,7 +1589,13 @@ 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
@@ -1604,7 +1611,7 @@ 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