From:   Uladzislau Rezki <urezki@gmail.com>
Date:   Wed, 1 Feb 2023 18:19:49 +0100
To:     Pablo Neira Ayuso <pablo@netfilter.org>
Cc:     Julian Anastasov <ja@ssi.bg>,
        "Uladzislau Rezki (Sony)" <urezki@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>, RCU <rcu@vger.kernel.org>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>,
        Jens Axboe <axboe@kernel.dk>,
        Philipp Reisner <philipp.reisner@linbit.com>,
        Bryan Tan <bryantan@vmware.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Eric Dumazet <edumazet@google.com>,
        Bob Pearson <rpearsonhpe@gmail.com>,
        Ariel Levkovich <lariel@nvidia.com>,
        Theodore Ts'o <tytso@mit.edu>, Jiri Wiesner <jwiesner@suse.de>
Subject: Re: [PATCH 10/13] ipvs: Rename kfree_rcu() to kfree_rcu_mightsleep()
Message-ID: <Y9qfNV0IX1tBsTxP@pc636>
References: <20230201150954.409693-1-urezki@gmail.com>
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 <Y9qc+lgR1CgdszKs@salvia>
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On Wed, Feb 01, 2023 at 06:10:18PM +0100, Pablo Neira Ayuso wrote:
> On Wed, Feb 01, 2023 at 06:12:04PM +0200, Julian Anastasov wrote:
> > 
> > 	Hello,
> > 
> > On Wed, 1 Feb 2023, Pablo Neira Ayuso wrote:
> > 
> > > Hi,
> > > 
> > > On Wed, Feb 01, 2023 at 04:09:51PM +0100, Uladzislau Rezki (Sony) wrote:
> > > > The kfree_rcu()'s single argument name is deprecated therefore
> > > > rename it to kfree_rcu_mightsleep() variant. The goal is explicitly
> > > > underline that it is for sleepable contexts.
> > > > 
> > > > Cc: Julian Anastasov <ja@ssi.bg>
> > > > Cc: Pablo Neira Ayuso <pablo@netfilter.org>
> > > > Cc: Jiri Wiesner <jwiesner@suse.de>
> > > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > > > ---
> > > >  net/netfilter/ipvs/ip_vs_est.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
> > > > index ce2a1549b304..a39baf6d1367 100644
> > > > --- a/net/netfilter/ipvs/ip_vs_est.c
> > > > +++ b/net/netfilter/ipvs/ip_vs_est.c
> > > > @@ -549,7 +549,7 @@ void ip_vs_stop_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats)
> > > >  	__set_bit(row, kd->avail);
> > > >  	if (!kd->tick_len[row]) {
> > > >  		RCU_INIT_POINTER(kd->ticks[row], NULL);
> > > > -		kfree_rcu(td);
> > > 
> > > I also found this kfree_rcu() without rcu_head call a few weeks ago.
> > > 
> > > @Wiesner, @Julian: Any chance this can be turned into kfree_rcu(td, rcu_head); ?
> > 
> > 	Yes, as simple as this:
> > 
> > diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> > index c6c61100d244..6d71a5ff52df 100644
> > --- a/include/net/ip_vs.h
> > +++ b/include/net/ip_vs.h
> > @@ -461,6 +461,7 @@ void ip_vs_stats_free(struct ip_vs_stats *stats);
> >  
> >  /* Multiple chains processed in same tick */
> >  struct ip_vs_est_tick_data {
> > +	struct rcu_head		rcu_head;
> >  	struct hlist_head	chains[IPVS_EST_TICK_CHAINS];
> >  	DECLARE_BITMAP(present, IPVS_EST_TICK_CHAINS);
> >  	DECLARE_BITMAP(full, IPVS_EST_TICK_CHAINS);
> > diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
> > index df56073bb282..25c7118d9348 100644
> > --- a/net/netfilter/ipvs/ip_vs_est.c
> > +++ b/net/netfilter/ipvs/ip_vs_est.c
> > @@ -549,7 +549,7 @@ void ip_vs_stop_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats)
> >  	__set_bit(row, kd->avail);
> >  	if (!kd->tick_len[row]) {
> >  		RCU_INIT_POINTER(kd->ticks[row], NULL);
> > -		kfree_rcu(td);
> > +		kfree_rcu(td, rcu_head);
> >  	}
> >  	kd->est_count--;
> >  	if (kd->est_count) {
> > 
> > 	I was about to reply to Uladzislau Rezki but his patchset
> > looks more like a renaming, so I'm not sure how we are about
> > to integrate this change, as separate patch or as part of his
> > patchset. I don't have preference, just let me know how to
> > handle it.
> 
> @Uladzislau Rezki: Are you fine with dropping this patch from your
> series and Julian will send us a patch for inclusion into net-next to
> use the kfree_rcu(x, rcu_head) variant?
Absolutely. So i will drop it from my series.

Thanks!

--
Uladzislau Rezki