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From: "Paul E. McKenney" <paulmck@kernel.org>
To: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: josh@joshtriplett.org, rostedt@goodmis.org,
	mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
	joel@joelfernandes.org, rcu@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rcu/tree: Force quiescent state on callback overload
Date: Sun, 21 Jun 2020 12:50:52 -0700
Message-ID: <20200621195052.GF9247@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <1592764647-2452-1-git-send-email-neeraju@codeaurora.org>

On Mon, Jun 22, 2020 at 12:07:27AM +0530, Neeraj Upadhyay wrote:
> On callback overload, we want to force quiescent state immediately,
> for the first and second fqs. Enforce the same, by including
> RCU_GP_FLAG_OVLD flag, in fqsstart check.
> 
> Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>

Good catch!

But what did you do to verify that this change does the right thing?

						Thanx, Paul

> ---
>  kernel/rcu/tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index d0988a1..6226bfb 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1865,7 +1865,7 @@ static void rcu_gp_fqs_loop(void)
>  			break;
>  		/* If time for quiescent-state forcing, do it. */
>  		if (!time_after(rcu_state.jiffies_force_qs, jiffies) ||
> -		    (gf & RCU_GP_FLAG_FQS)) {
> +		    (gf & (RCU_GP_FLAG_FQS | RCU_GP_FLAG_OVLD))) {
>  			trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq,
>  					       TPS("fqsstart"));
>  			rcu_gp_fqs(first_gp_fqs);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-21 18:37 Neeraj Upadhyay
2020-06-21 19:50 ` Paul E. McKenney [this message]
2020-06-21 20:00   ` Neeraj Upadhyay
2020-06-22  3:13     ` Paul E. McKenney
2020-06-22  3:46       ` Neeraj Upadhyay
2020-06-22 22:53         ` Paul E. McKenney
2020-06-23  6:19           ` Neeraj Upadhyay
2020-06-23 15:42 ` Joel Fernandes
2020-06-23 16:29   ` Paul E. McKenney

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