Re: [PATCH v3] kcov: move kcov_remote_data to task_struct for RT and remove local_lock

[Sebastian Andrzej Siewior]

On 2026-05-22 00:28:26 [+0900], Tetsuo Handa wrote:
> > If handling softirqs in parallel might be indeed a reasonable solution.
> > You would need to use the per-task area instead per-CPU for this in the
> > softirq case on PREEMPT_RT. But the other checks, such as in_task()
> > work as intended on both.
> 
> https://share.google/aimode/PveuuU5od6d1lAwit (expires in 7 days) says
> 
>   Non-PREEMPT_RT Kernel: in_task() returns false while executing a softirq.
> 
>   PREEMPT_RT Kernel: in_task() returns true while executing a softirq (unless
>                      nested inside a hard interrupt or NMI).
> 
> Is this explanation wrong?

Yes. If a softirq is executed (in_serving_softirq() returns true) then
in_task() returns false. On PREEMPT_RT and on non-PREEMPT_RT kernels. It
is irrelevant if the softirq is executed at the end of an interrupt
handler and within ksoftirqd.

Sebastian