Re: [PATCH v2 2/5] preempt/dynamic: Introduce preempt mode accessors

On 11/11/21 09:54, Marco Elver wrote:

On Wed, Nov 10, 2021 at 08:24PM +0000, Valentin Schneider wrote:
[...]

quoted

+#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)
+

Can these callables be real functions in all configs, making the
!DYNAMIC ones just static inline bool ones? That'd catch invalid use in
#if etc. in all configs.

Ack

quoted

 /*
  * 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;		 \
+	}

This needs an EXPORT_SYMBOL, so it's usable from modules like the
kcsan_test module.

Ah, wasn't sure about that one, thanks!