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

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:

quoted

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 <redacted>

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

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

quoted

---
 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