Re: [PATCH v1 4/5] kvfree_rcu: Refactor kfree_rcu_monitor() function

[Andrew Morton]

On Wed, 28 Apr 2021 15:44:21 +0200 "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx> wrote:

> Rearm the monitor work directly from its own function that
> is kfree_rcu_monitor(). So this patch puts the invocation
> timing control in one place.
>
> ...
>
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3415,37 +3415,44 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp)
>  	return !repeat;
>  }
>  
> -static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp,
> -					  unsigned long flags)
> +/*
> + * This function queues a new batch. If success or nothing to
> + * drain it returns 1. Otherwise 0 is returned indicating that
> + * a reclaim kthread has not processed a previous batch.
> + */
> +static inline int kfree_rcu_drain(struct kfree_rcu_cpu *krcp)
>  {
> +	unsigned long flags;
> +	int ret;
> +
> +	raw_spin_lock_irqsave(&krcp->lock, flags);
> +
>  	// Attempt to start a new batch.
> -	if (queue_kfree_rcu_work(krcp)) {
> +	ret = queue_kfree_rcu_work(krcp);

This code has changed slightly in mainline.  Can you please redo,
retest and resend?

> +	if (ret)
>  		// Success! Our job is done here.
>  		krcp->monitor_todo = false;
> -		raw_spin_unlock_irqrestore(&krcp->lock, flags);
> -		return;
> -	}

It's conventional to retain the braces here, otherwise the code looks
weird.  Unless you're a python programmer ;)