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

[Valentin Schneider <valentin.schneider@arm.com>]

On 11/11/21 09:54, Marco Elver wrote:
> On Wed, Nov 10, 2021 at 08:24PM +0000, Valentin Schneider wrote:
> [...]
>> +#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

>>  /*
>>   * 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!