Re: [PATCH v2 4/5] kscan: Use preemption model accessors

[Marco Elver]

Subject s/kscan/kcsan/

On Wed, Nov 10, 2021 at 08:24PM +0000, Valentin Schneider wrote:
> Per PREEMPT_DYNAMIC, checking CONFIG_PREEMPT doesn't tell you the actual
> preemption model of the live kernel. Use the newly-introduced accessors
> instead.
> 
> Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx>

Reviewed-by: Marco Elver <elver@xxxxxxxxxx>

Though it currently doesn't compile as a module due to missing
EXPORT_SYMBOL of is_preempt*().

> ---
>  kernel/kcsan/kcsan_test.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c
> index dc55fd5a36fc..14d811eb9a21 100644
> --- a/kernel/kcsan/kcsan_test.c
> +++ b/kernel/kcsan/kcsan_test.c
> @@ -1005,13 +1005,13 @@ static const void *nthreads_gen_params(const void *prev, char *desc)
>  	else
>  		nthreads *= 2;
>  
> -	if (!IS_ENABLED(CONFIG_PREEMPT) || !IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER)) {
> +	if (!is_preempt_full() || !IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER)) {
>  		/*
>  		 * Without any preemption, keep 2 CPUs free for other tasks, one
>  		 * of which is the main test case function checking for
>  		 * completion or failure.
>  		 */
> -		const long min_unused_cpus = IS_ENABLED(CONFIG_PREEMPT_NONE) ? 2 : 0;
> +		const long min_unused_cpus = is_preempt_none() ? 2 : 0;
>  		const long min_required_cpus = 2 + min_unused_cpus;
>  
>  		if (num_online_cpus() < min_required_cpus) {
> -- 
> 2.25.1