Date:   Wed, 1 Feb 2023 18:12:04 +0200 (EET)
From:   Julian Anastasov <ja@ssi.bg>
To:     Pablo Neira Ayuso <pablo@netfilter.org>
cc:     "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()
In-Reply-To: <Y9qLB6Zyx5atcFUV@salvia>
Message-ID: <7e87836a-c72-eefd-9c74-fc2637accd2@ssi.bg>
References: <20230201150954.409693-1-urezki@gmail.com> <Y9qLB6Zyx5atcFUV@salvia>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk


	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.

Regards

--
Julian Anastasov <ja@ssi.bg>