netdev - Re: [PATCH net-next] tcp: use 2-arg optimal variant of kfree

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Message-ID: <Y43RXNu0cck6wo/0@pc636>
Date:   Mon, 5 Dec 2022 12:09:16 +0100
From:   Uladzislau Rezki <urezki@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     paulmck@...nel.org, Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        eric.dumazet@...il.com, Dmitry Safonov <dima@...sta.com>,
        rcu@...r.kernel.org
Subject: Re: [PATCH net-next] tcp: use 2-arg optimal variant of kfree_rcu()

Hello, Eric.

> +rcu for archives 
> 
> > On Dec 2, 2022, at 7:16 PM, Joel Fernandes <joel@...lfernandes.org> wrote:
> > 
> > On Sat, Dec 3, 2022 at 12:12 AM Joel Fernandes <joel@...lfernandes.org> wrote:
> >> 
> >>> On Sat, Dec 3, 2022 at 12:03 AM Paul E. McKenney <paulmck@...nel.org> wrote:
> >>> 
> >>> On Fri, Dec 02, 2022 at 11:49:59PM +0000, Joel Fernandes wrote:
> >>>> On Fri, Dec 02, 2022 at 05:28:47AM +0000, Eric Dumazet wrote:
> >>>>> kfree_rcu(1-arg) should be avoided as much as possible,
> >>>>> since this is only possible from sleepable contexts,
> >>>>> and incurr extra rcu barriers.
> >>>>> 
> >>>>> I wish the 1-arg variant of kfree_rcu() would
> >>>>> get a distinct name, like kfree_rcu_slow()
> >>>>> to avoid it being abused.
>
<snip>
tcp: use 2-arg optimal variant of kfree_rcu()
Date: Fri,  2 Dec 2022 05:28:47 +0000	[thread overview]
Message-ID: <20221202052847.2623997-1-edumazet@...gle.com> (raw)

kfree_rcu(1-arg) should be avoided as much as possible,
since this is only possible from sleepable contexts,
and incurr extra rcu barriers.

I wish the 1-arg variant of kfree_rcu() would
get a distinct name, like kfree_rcu_slow()
to avoid it being abused.

Fixes: 459837b522f7 ("net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Dmitry Safonov <dima@...sta.com>
Cc: Paul E. McKenney <paulmck@...nel.org>
<snip>

Could you please clarify a little bit about why/how have you came
up with a patch that you posted with "Fixes" tag? I mean you run
into:
  - performance degrade;
  - simple typo;
  - etc.

Thank you.

--
Uladzislau Rezki