Re: [PATCH 2/9] rv: Fix read_lock scope in per-task DA cleanup

[Wen Yang <wen.yang@linux.dev>]

Correct.  tasklist_lock is only needed to guard 
for_each_process_thread(); idle tasks are bound to their CPU and are not 
subject to exit/reparent, so no lock is needed for for_each_present_cpu().


Reviewed-by: Wen Yang <wen.yang@linux.dev>


On 5/12/26 22:02, Gabriele Monaco wrote:
> The da_monitor_reset_all() function for per-task monitors takes
> tasklist_lock while iterating over tasks, then keeps it also while
> iterating over idle tasks (one per CPU). The latter is not necessary
> since the lock needs to guard only for_each_process_thread().
> 
> Use a scoped_guard for more compact syntax and adjust the scope only
> where the lock is necessary.
> 
> Fixes: 30984ccf31b7f ("rv: Refactor da_monitor to minimise macros")
> Fixes: 8259cb14a7068 ("rv: Reset per-task monitors also for idle tasks")
> Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
> ---
>   include/rv/da_monitor.h | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h
> index 39765ff6f098..250888812125 100644
> --- a/include/rv/da_monitor.h
> +++ b/include/rv/da_monitor.h
> @@ -272,12 +272,12 @@ static void da_monitor_reset_all(void)
>   	struct task_struct *g, *p;
>   	int cpu;
>   
> -	read_lock(&tasklist_lock);
> -	for_each_process_thread(g, p)
> -		da_monitor_reset(da_get_monitor(p));
> +	scoped_guard(read_lock, &tasklist_lock) {
> +		for_each_process_thread(g, p)
> +			da_monitor_reset(da_get_monitor(p));
> +	}
>   	for_each_present_cpu(cpu)
>   		da_monitor_reset(da_get_monitor(idle_task(cpu)));
> -	read_unlock(&tasklist_lock);
>   }
>   
>   /*