linux-kernel - Re: [PATCH 1/2] rcu/kvfree: Remove useless monitor

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Date:   Fri, 3 Jun 2022 11:51:34 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <neeraj.iitr10@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 1/2] rcu/kvfree: Remove useless monitor_todo flag

> On Thu, Jun 02, 2022 at 10:06:43AM +0200, Uladzislau Rezki (Sony) wrote:
> > From: "Joel Fernandes (Google)" <joel@...lfernandes.org>
> > 
> > monitor_todo is not needed as the work struct already tracks
> > if work is pending. Just use that to know if work is pending
> > using schedule_delayed_work() helper.
> > 
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> > Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> > ---
> >  kernel/rcu/tree.c | 33 ++++++++++++++++-----------------
> >  1 file changed, 16 insertions(+), 17 deletions(-)
> > 
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 222d59299a2a..fd16c0b46d9e 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -3295,7 +3295,6 @@ struct kfree_rcu_cpu_work {
> >   * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
> >   * @lock: Synchronize access to this structure
> >   * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES
> > - * @monitor_todo: Tracks whether a @monitor_work delayed work is pending
> >   * @initialized: The @rcu_work fields have been initialized
> >   * @count: Number of objects for which GP not started
> >   * @bkvcache:
> > @@ -3320,7 +3319,6 @@ struct kfree_rcu_cpu {
> >  	struct kfree_rcu_cpu_work krw_arr[KFREE_N_BATCHES];
> >  	raw_spinlock_t lock;
> >  	struct delayed_work monitor_work;
> > -	bool monitor_todo;
> >  	bool initialized;
> >  	int count;
> >  
> > @@ -3500,6 +3498,18 @@ static void kfree_rcu_work(struct work_struct *work)
> >  	}
> >  }
> >  
> > +static bool
> > +need_offload_krc(struct kfree_rcu_cpu *krcp)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < FREE_N_CHANNELS; i++)
> > +		if (krcp->bkvhead[i])
> > +			return true;
> > +
> > +	return !!krcp->head;
> > +}
> 
> Thanks for modifying my original patch to do this, and thanks for giving me
> the attribution for the patch. This function is a nice addition.
> 
It was you who did it :) Actually the second patch depends on it therefore 
i decided to upload it on behalf of you with slight modification hoping that
you would not mind.

>
> For the patch in its entirety:
> Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> 
Thanks for the review!

--
Uladzislau Rezki