From: Jarek Poplawski <jarkao2@gmail•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: Changli Gao <xiaosuo@gmail•com>,
David Miller <davem@davemloft•net>,
netdev <netdev@vger•kernel.org>,
Stephen Hemminger <shemminger@vyatta•com>,
Patrick McHardy <kaber@trash•net>
Subject: Re: [PATCH] pkt_sched: gen_kill_estimator() rcu fixes
Date: Wed, 9 Jun 2010 10:41:00 +0000 [thread overview]
Message-ID: <20100609104100.GB7308@ff.dom.local> (raw)
In-Reply-To: <1276077416.2442.97.camel@edumazet-laptop>
On Wed, Jun 09, 2010 at 11:56:56AM +0200, Eric Dumazet wrote:
...
> Updated patch follows :
>
> [PATCH] pkt_sched: gen_kill_estimator() rcu fixes
>
> gen_kill_estimator() API is a bit misleading, since caller
I'd call it incomplete or simply buggy. Plus a tiny note below.
> should make sure an RCU grace period is respected before
> freeing stats_lock.
>
> This was partially addressed in commit 5d944c640b4
> (gen_estimator: deadlock fix), but same problem exist for all
> gen_kill_estimator() users, if lock they use is not already rcu
> protected.
>
> A code review shows xt_RATEEST.c, act_api.c, act_police.c have this
> problem. Other are ok because they use qdisc lock.
>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail•com>
> ---
...
> diff --git a/net/netfilter/xt_RATEEST.c b/net/netfilter/xt_RATEEST.c
> index 69c01e1..096b18b 100644
> --- a/net/netfilter/xt_RATEEST.c
> +++ b/net/netfilter/xt_RATEEST.c
> @@ -60,13 +60,18 @@ struct xt_rateest *xt_rateest_lookup(const char *name)
> }
> EXPORT_SYMBOL_GPL(xt_rateest_lookup);
>
> +static void xt_rateeset_free_rcu(struct rcu_head *head)
> +{
> + kfree(container_of(head, struct xt_rateest, rcu));
> +}
> +
> void xt_rateest_put(struct xt_rateest *est)
> {
> mutex_lock(&xt_rateest_mutex);
> if (--est->refcnt == 0) {
> hlist_del(&est->list);
> gen_kill_estimator(&est->bstats, &est->rstats);
> - kfree(est);
> + call_rcu(&est->rcu, xt_rateeset_free_rcu);
Spelling suggestion: xt_rateest_free_rcu?
Since it's only 3 places I'd consider adding little comments,
who needs this call_rcu (like in qdisc_destroy).
Anyway this patch looks OK to me.
Jarek P.
next prev parent reply other threads:[~2010-06-09 10:41 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-07 14:32 [PATCH net-next-2.6] pkt_sched: gen_estimator: kill est_lock rwlock Eric Dumazet
2010-06-07 14:53 ` Changli Gao
2010-06-07 15:30 ` Eric Dumazet
2010-06-07 15:55 ` Eric Dumazet
2010-06-07 16:56 ` [PATCH net-next-2.6 v2] " Eric Dumazet
2010-06-07 17:18 ` [PATCH net-2.6] pkt_sched: gen_estimator: add a new lock Eric Dumazet
2010-06-08 1:00 ` Changli Gao
2010-06-08 4:30 ` Eric Dumazet
2010-06-08 4:57 ` Changli Gao
2010-06-08 4:58 ` Eric Dumazet
2010-06-08 5:20 ` Changli Gao
2010-06-08 5:39 ` Eric Dumazet
2010-06-09 9:39 ` [PATCH net-2.6 v2] " Eric Dumazet
2010-06-09 11:33 ` Jarek Poplawski
2010-06-09 11:55 ` Eric Dumazet
2010-06-11 5:54 ` David Miller
2010-06-08 12:15 ` [PATCH net-next-2.6 v2] pkt_sched: gen_estimator: kill est_lock rwlock Jarek Poplawski
2010-06-08 12:27 ` Eric Dumazet
2010-06-08 12:40 ` Jarek Poplawski
2010-06-08 19:29 ` Jarek Poplawski
2010-06-08 19:45 ` Eric Dumazet
2010-06-08 20:24 ` Jarek Poplawski
2010-06-08 20:52 ` Eric Dumazet
2010-06-08 21:18 ` Jarek Poplawski
2010-06-09 6:13 ` pkt_sched: gen_estimator: more fuel for Jarek and Changli Eric Dumazet
2010-06-09 6:51 ` Jarek Poplawski
2010-06-09 7:36 ` Eric Dumazet
2010-06-09 8:14 ` Jarek Poplawski
2010-06-09 9:40 ` [PATCH] pkt_sched: gen_kill_estimator() rcu fixes Eric Dumazet
2010-06-09 9:56 ` Eric Dumazet
2010-06-09 10:41 ` Jarek Poplawski [this message]
2010-06-09 12:09 ` Eric Dumazet
2010-06-09 12:50 ` Jarek Poplawski
2010-06-09 13:05 ` Eric Dumazet
2010-06-12 1:39 ` David Miller
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