On Sun, Dec 14, 2025 at 10:49:04AM +0800, Zqiang wrote:
> The cblist_init_generic() is executed during the CPU early boot
> phase due to commit:30ef09635b9e ("rcu-tasks: Initialize callback
> lists at rcu_init() time"), at this time, only one boot CPU is
> online. this commit therefore use WRITE_ONCE() to replace the
> smp_store_release() to assigning rtp->percpu_enqueue_lim in the
> cblist_init_generic().
>
> Signed-off-by: Zqiang <[email protected]>
Good eyes, thank you!
But in that case, we are running on a single CPU with interrupts disables,
so do we even need WRITE_ONCE()?
Thanx, Paul
> ---
> kernel/rcu/tasks.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 76f952196a29..f763f60d5e50 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -292,7 +292,7 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
> shift++;
> WRITE_ONCE(rtp->percpu_enqueue_shift, shift);
> WRITE_ONCE(rtp->percpu_dequeue_lim, lim);
> - smp_store_release(&rtp->percpu_enqueue_lim, lim);
> + WRITE_ONCE(rtp->percpu_enqueue_lim, lim);
>
> pr_info("%s: Setting shift to %d and lim to %d rcu_task_cb_adjust=%d
> rcu_task_cpu_ids=%d.\n",
> rtp->name, data_race(rtp->percpu_enqueue_shift),
> data_race(rtp->percpu_enqueue_lim),
> --
> 2.48.1
>
