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From: Eric Dumazet <edumazet@google.com>
To: Florian Westphal <fw@strlen.de>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
	netfilter-devel@vger.kernel.org, netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH net] netfilter: nf_tables: prefer kfree_rcu(ptr, rcu) variant
Date: Tue, 22 Feb 2022 12:07:05 -0800	[thread overview]
Message-ID: <CANn89iLz4yML_RktHUadAkU966h9QCRJQ=cMPVzUDU7dHXg0sw@mail.gmail.com> (raw)
In-Reply-To: <20220222194605.GA28705@breakpoint.cc>

On Tue, Feb 22, 2022 at 11:46 AM Florian Westphal <fw@strlen.de> wrote:
>
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > From: Eric Dumazet <edumazet@google.com>
> >
> > While kfree_rcu(ptr) _is_ supported, it has some limitations.
> >
> > Given that 99.99% of kfree_rcu() users [1] use the legacy
> > two parameters variant, and @catchall objects do have an rcu head,
> > simply use it.
> >
> > Choice of kfree_rcu(ptr) variant was probably not intentional.
>
> In case someone wondered, this causes expensive
> sycnhronize_rcu + kfree for each removal operation.

This fallback to synchronize_rcu() only happens if kvfree_call_rcu() has been
unable to allocate a new block of memory.

But yes, I guess I would add a Fixes: tag, because we can easily avoid
this potential issue.

Pablo, if not too late:

Fixes: aaa31047a6d2 ("netfilter: nftables: add catch-all set element support")

>
> Reviewed-by: Florian Westphal <fw@strlen.de>
>

  reply	other threads:[~2022-02-22 20:07 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-22 18:13 [PATCH net] netfilter: nf_tables: prefer kfree_rcu(ptr, rcu) variant Eric Dumazet
2022-02-22 19:46 ` Florian Westphal
2022-02-22 20:07   ` Eric Dumazet [this message]
2022-02-23  8:22     ` Pablo Neira Ayuso

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