Re: [PATCH v2] workqueue: annotate racy p->wake_cpu accesses in kick_pool_pick()

[Tejun Heo <tj@kernel.org>]

Hello, Breno.

On Tue, Aug 11, 2026 at 02:55:56AM -0700, Breno Leitao wrote:
> The race is harmless, this patch only acknowledge that this is racy and
> it is fine, silenting KCSAN.

Can you say why it's harmless? wake_cpu is a best-effort placement hint.
Every writer stores a valid CPU id and the wakeup path validates it
through select_task_rq(), so a racy value only affects where the worker
wakes up. Also, s/acknowledge/acknowledges/ and s/silenting/silencing/.

> -	if (!pool->attrs->affn_strict &&
> -	    !cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) {
> +	bool wake_cpu_in_pod = cpumask_test_cpu(READ_ONCE(p->wake_cpu),
> +						pool->attrs->__pod_cpumask);
> +
> +	if (!pool->attrs->affn_strict && !wake_cpu_in_pod) {

The hoist drops the !affn_strict short-circuit and adds a declaration
after statements. Can you keep the test inline in the condition?

	if (!pool->attrs->affn_strict &&
	    !cpumask_test_cpu(READ_ONCE(p->wake_cpu),
			      pool->attrs->__pod_cpumask)) {

Thanks.

-- 
tejun