linux-kernel - Re: [PATCH 3/6] sched_ext: Make @rf optional for dispatch_to_local

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Message-ID: <Zo5Ncd8DxGSVztoH@gpd>
Date: Wed, 10 Jul 2024 10:59:29 +0200
From: Andrea Righi <righi.andrea@...il.com>
To: Tejun Heo <tj@...nel.org>
Cc: void@...ifault.com, linux-kernel@...r.kernel.org, kernel-team@...a.com,
	schatzberg.dan@...il.com, mingo@...hat.com, peterz@...radead.org,
	changwoo@...lia.com
Subject: Re: [PATCH 3/6] sched_ext: Make @rf optional for
 dispatch_to_local_dsq()

On Tue, Jul 09, 2024 at 11:21:09AM -1000, Tejun Heo wrote:
...
> @@ -2052,17 +2052,20 @@ static bool move_task_to_local_dsq(struct rq *rq, struct task_struct *p,
>  static void dispatch_to_local_dsq_lock(struct rq *rq, struct rq_flags *rf,
>  				       struct rq *src_rq, struct rq *dst_rq)
>  {
> -	rq_unpin_lock(rq, rf);
> +	if (rf)
> +		rq_unpin_lock(rq, rf);
>  
>  	if (src_rq == dst_rq) {
>  		raw_spin_rq_unlock(rq);
>  		raw_spin_rq_lock(dst_rq);
>  	} else if (rq == src_rq) {
>  		double_lock_balance(rq, dst_rq);
> -		rq_repin_lock(rq, rf);
> +		if (rf)
> +			rq_repin_lock(rq, rf);
>  	} else if (rq == dst_rq) {
>  		double_lock_balance(rq, src_rq);
> -		rq_repin_lock(rq, rf);
> +		if (rf)
> +			rq_repin_lock(rq, rf);
>  	} else {
>  		raw_spin_rq_unlock(rq);
>  		double_rq_lock(src_rq, dst_rq);

Not a blocker, but would it make sense to provide some wrappers for
rq_unpin_lock() / rq_repin_lock() to simply return if rf == NULL?

Maybe it can help to make the code a bit more readable.

-Andrea