linux-kernel - Re: [PATCH 1/2] locktorture: doesn't check nreaders

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Message-ID: <20200917165817.GK29330@paulmck-ThinkPad-P72>
Date:   Thu, 17 Sep 2020 09:58:17 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Hou Tao <houtao1@...wei.com>
Cc:     Davidlohr Bueso <dave@...olabs.net>,
        Josh Triplett <josh@...htriplett.org>,
        linux-kernel@...r.kernel.org, rcu@...r.kernel.org
Subject: Re: [PATCH 1/2] locktorture: doesn't check nreaders_stress when no
 readlock support

On Thu, Sep 17, 2020 at 09:59:09PM +0800, Hou Tao wrote:
> To ensure there is always at least one locking thread.
> 
> Signed-off-by: Hou Tao <houtao1@...wei.com>
> ---
>  kernel/locking/locktorture.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
> index 9cfa5e89cff7f..bebdf98e6cd78 100644
> --- a/kernel/locking/locktorture.c
> +++ b/kernel/locking/locktorture.c
> @@ -868,7 +868,8 @@ static int __init lock_torture_init(void)
>  		goto unwind;
>  	}
>  
> -	if (nwriters_stress == 0 && nreaders_stress == 0) {
> +	if (nwriters_stress == 0 &&
> +	    (!cxt.cur_ops->readlock || nreaders_stress == 0)) {

You lost me on this one.  How does it help to allow tests with zero
writers on exclusive locks?  Or am I missing something subtle here?

							Thanx, Paul

>  		pr_alert("lock-torture: must run at least one locking thread\n");
>  		firsterr = -EINVAL;
>  		goto unwind;
> -- 
> 2.25.0.4.g0ad7144999
>