Re: [PATCH v3 01/14] ACPI: APEI: Remove redundant rcu_read_lock/unlock() in spin_lock

[Hanjun Guo <guohanjun@huawei.com>]

On 2025/9/16 12:47, pengdonglin wrote:
> From: pengdonglin <pengdonglin@xiaomi.com>
> 
> Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions")
> there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
> rcu_read_lock_sched() in terms of RCU read section and the relevant grace
> period. That means that spin_lock(), which implies rcu_read_lock_sched(),
> also implies rcu_read_lock().
> 
> There is no need no explicitly start a RCU read section if one has already
> been started implicitly by spin_lock().
> 
> Simplify the code and remove the inner rcu_read_lock() invocation.
> 
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Hanjun Guo <guohanjun@huawei.com>
> Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
> Signed-off-by: pengdonglin <dolinux.peng@gmail.com>
> ---
>   drivers/acpi/apei/ghes.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index a0d54993edb3..97ee19f2cae0 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -1207,12 +1207,10 @@ static int ghes_notify_hed(struct notifier_block *this, unsigned long event,
>   	int ret = NOTIFY_DONE;
>   
>   	spin_lock_irqsave(&ghes_notify_lock_irq, flags);
> -	rcu_read_lock();
>   	list_for_each_entry_rcu(ghes, &ghes_hed, list) {
>   		if (!ghes_proc(ghes))
>   			ret = NOTIFY_OK;
>   	}
> -	rcu_read_unlock();
>   	spin_unlock_irqrestore(&ghes_notify_lock_irq, flags);
>   
>   	return ret;

Reviewed-by: Hanjun Guo <guohanjun@huawei.com>

Thanks
Hanjun