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

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

On 11/11/21 10:11, Marco Elver wrote:
> Subject s/kscan/kcsan/
>

Woops...

> 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@arm.com>
>
> Reviewed-by: Marco Elver <elver@google.com>
>
> 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