From eba9f08293d76370049ec85581ab3d7f6d069e3e Mon Sep 17 00:00:00 2001 From: zhuguangqing Date: Wed, 14 Oct 2020 22:02:20 +0800 Subject: [PATCH 1/2] sched: Replace zero-length array with flexible-array In the following commit: 04f5c362ec6d: ("sched/fair: Replace zero-length array with flexible-array") a zero-length array cpumask[0] has been replaced with cpumask[]. But there is still a cpumask[0] in 'struct sched_group_capacity' which was missed. The point of using [] instead of [0] is that with [] the compiler will generate a build warning if it isn't the last member of a struct. [ mingo: Rewrote the changelog. ] Signed-off-by: zhuguangqing Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20201014140220.11384-1-zhuguangqing83@gmail.com --- kernel/sched/sched.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 28709f6b0975..648f02363ff9 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1471,7 +1471,7 @@ struct sched_group_capacity { int id; #endif - unsigned long cpumask[0]; /* Balance mask */ + unsigned long cpumask[]; /* Balance mask */ }; struct sched_group { From a73f863af4ce9730795eab7097fb2102e6854365 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Tue, 13 Oct 2020 07:31:14 +0200 Subject: [PATCH 2/2] sched/features: Fix !CONFIG_JUMP_LABEL case 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 Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Juri Lelli Signed-off-by: Ingo Molnar Acked-by: Patrick Bellasi Reviewed-by: Valentin Schneider Link: https://lore.kernel.org/r/20201013053114.160628-1-juri.lelli@redhat.com --- 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 8160ab5263f8..d2003a7d5ab5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -44,7 +44,7 @@ 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 648f02363ff9..df80bfcea92e 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;