Re: [PATCH] arm64: Remove the check for CONFIG_TINY_RCU

[Ryo Takakura]

Hi Will, 

On 2024-10-14, Will Deacon wrote:
>On Sat, Sep 14, 2024 at 06:00:40PM +0900, Ryo Takakura wrote:
>> Since the commit 4b3dc9679cf77 ("arm64: force CONFIG_SMP=y and remove
>> redundant #ifdefs"), arm64 defaults to CONFIG_SMP but TINY_RCU is cofigured
>> only for !SMP systems.
>> 
>> Remove the check for CONFIG_TINY_RCU as it should always be false.
>> 
>> Signed-off-by: Ryo Takakura <ryotkkr98@xxxxxxxxx>
>> ---
>>  arch/arm64/kernel/entry-common.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
>> index b77a15955f28..a9765364fc67 100644
>> --- a/arch/arm64/kernel/entry-common.c
>> +++ b/arch/arm64/kernel/entry-common.c
>> @@ -40,7 +40,7 @@ static __always_inline void __enter_from_kernel_mode(struct pt_regs *regs)
>>  {
>>  	regs->exit_rcu = false;
>>  
>> -	if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
>> +	if (is_idle_task(current)) {
>>  		lockdep_hardirqs_off(CALLER_ADDR0);
>>  		ct_irq_enter();
>>  		trace_hardirqs_off_finish();
>
>I think this code was deliberately written to follow kernel/entry/common.c
>as closely as possible, as we should be able to switch over to that at
>some point.

Oh I see, thanks for taking a look at the patch!

>Come to think of it, Mark, what work is needed before we can move to the
>generic code? Is there anything you need a hand with?
>
>Will

If there is anything I can be of help, let me know!

Sincerely,
Ryo Takakura