[PATCH v2 2/5] preempt/dynamic: Introduce preempt mode accessors
From: Valentin Schneider <hidden>
Date: 2021-11-10 20:26:28
Also in:
linux-kbuild, lkml
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
CONFIG_PREEMPT{_NONE, _VOLUNTARY} designate either:
o The build-time preemption model when !PREEMPT_DYNAMIC
o The default boot-time preemption model when PREEMPT_DYNAMIC
IOW, using those on PREEMPT_DYNAMIC kernels is meaningless - the actual
model could have been set to something else by the "preempt=foo" cmdline
parameter.
Introduce a set of helpers to determine the actual preemption mode used by
the live kernel.
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Valentin Schneider <redacted>
---
include/linux/sched.h | 16 ++++++++++++++++
kernel/sched/core.c | 11 +++++++++++
2 files changed, 27 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5f8db54226af..0640d5622496 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h@@ -2073,6 +2073,22 @@ static inline void cond_resched_rcu(void) #endif } +#ifdef CONFIG_PREEMPT_DYNAMIC + +extern bool is_preempt_none(void); +extern bool is_preempt_voluntary(void); +extern bool is_preempt_full(void); + +#else + +#define is_preempt_none() IS_ENABLED(CONFIG_PREEMPT_NONE) +#define is_preempt_voluntary() IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY) +#define is_preempt_full() IS_ENABLED(CONFIG_PREEMPT) + +#endif + +#define is_preempt_rt() IS_ENABLED(CONFIG_PREEMPT_RT) + /* * Does a critical section need to be broken due to another * task waiting?: (technically does not depend on CONFIG_PREEMPTION,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 97047aa7b6c2..9db7f77e53c3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -6638,6 +6638,17 @@ static void __init preempt_dynamic_init(void) } } +#define PREEMPT_MODE_ACCESSOR(mode) \ + bool is_preempt_##mode(void) \ + { \ + WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \ + return preempt_dynamic_mode == preempt_dynamic_##mode; \ + } + +PREEMPT_MODE_ACCESSOR(none) +PREEMPT_MODE_ACCESSOR(voluntary) +PREEMPT_MODE_ACCESSOR(full) + #else /* !CONFIG_PREEMPT_DYNAMIC */ static inline void preempt_dynamic_init(void) { }
--
2.25.1