From: Cong Wang <xiyou.wangcong@gmail.com>
To: Vlad Buslov <vladbu@mellanox.com>
Cc: Jiri Pirko <jiri@resnulli.us>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next 01/12] net: sched: flower: don't check for rtnl on head dereference
Date: Fri, 1 Mar 2019 16:51:33 -0800 [thread overview]
Message-ID: <CAM_iQpXkjp3JVtY63kKvrmEkgBR7oUcO7vsDZhxMSUdF+CPONA@mail.gmail.com> (raw)
In-Reply-To: <vbfbm2vzs0u.fsf@mellanox.com>
On Thu, Feb 28, 2019 at 10:35 AM Vlad Buslov <vladbu@mellanox.com> wrote:
>
>
> On Thu 28 Feb 2019 at 00:49, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> > On Tue, Feb 26, 2019 at 6:57 AM Vlad Buslov <vladbu@mellanox.com> wrote:
> >>
> >>
> >> On Mon 25 Feb 2019 at 22:39, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> >> > On Mon, Feb 25, 2019 at 8:11 AM Vlad Buslov <vladbu@mellanox.com> wrote:
> >> >>
> >> >>
> >> >> On Fri 22 Feb 2019 at 19:32, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> >> >> >
> >> >> > So if it is no longer RCU any more, why do you still use
> >> >> > rcu_dereference_protected()? That is, why not just deref it as a raw
> >> >> > pointer?
> >> >
> >> >
> >> > Any answer for this question?
> >>
> >> I decided that since there is neither possibility of concurrent pointer
> >> assignment nor deallocation of object that it points to, most performant
> >> solution would be using rcu_dereference_protected() which is the only
> >> RCU dereference helper that doesn't use READ_ONCE. I now understand that
> >> this is confusing (and most likely doesn't provide any noticeable
> >> performance improvement anyway!) and will change this patch to use
> >> rcu_dereference_raw() as you suggest.
> >
> > Yeah, please make sure sparse is happy with that. :)
>
> I checked my flower change with sparse. It produced a lot of warnings,
> some of which are several years old. None in the code I changed though:
If so, we can address this later, it is not urgent.
next prev parent reply other threads:[~2019-03-02 0:51 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 7:47 [PATCH net-next 00/12] Refactor flower classifier to remove dependency on rtnl lock Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 01/12] net: sched: flower: don't check for rtnl on head dereference Vlad Buslov
2019-02-18 19:08 ` Cong Wang
2019-02-19 9:45 ` Vlad Buslov
2019-02-20 22:33 ` Cong Wang
2019-02-21 17:45 ` Vlad Buslov
2019-02-22 19:32 ` Cong Wang
2019-02-25 16:11 ` Vlad Buslov
2019-02-25 22:39 ` Cong Wang
2019-02-26 14:57 ` Vlad Buslov
2019-02-28 0:49 ` Cong Wang
2019-02-28 18:35 ` Vlad Buslov
2019-03-02 0:51 ` Cong Wang [this message]
2019-02-14 7:47 ` [PATCH net-next 02/12] net: sched: flower: refactor fl_change Vlad Buslov
2019-02-14 20:34 ` Stefano Brivio
2019-02-15 10:38 ` Vlad Buslov
2019-02-15 10:47 ` Stefano Brivio
2019-02-15 16:25 ` Vlad Buslov
2019-02-18 18:20 ` Stefano Brivio
2019-02-14 7:47 ` [PATCH net-next 03/12] net: sched: flower: introduce reference counting for filters Vlad Buslov
2019-02-14 20:34 ` Stefano Brivio
2019-02-15 11:22 ` Vlad Buslov
2019-02-15 12:32 ` Stefano Brivio
2019-02-14 7:47 ` [PATCH net-next 04/12] net: sched: flower: track filter deletion with flag Vlad Buslov
2019-02-14 20:49 ` Stefano Brivio
2019-02-15 15:54 ` Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 05/12] net: sched: flower: add reference counter to flower mask Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 06/12] net: sched: flower: handle concurrent mask insertion Vlad Buslov
2019-02-15 22:46 ` Stefano Brivio
2019-02-14 7:47 ` [PATCH net-next 07/12] net: sched: flower: protect masks list with spinlock Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 08/12] net: sched: flower: handle concurrent filter insertion in fl_change Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf proto deletion Vlad Buslov
2019-02-18 20:47 ` Cong Wang
2019-02-19 14:08 ` Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 10/12] net: sched: flower: protect flower classifier state with spinlock Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 11/12] net: sched: flower: track rtnl lock state Vlad Buslov
2019-02-15 22:46 ` Stefano Brivio
2019-02-18 9:35 ` Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 12/12] net: sched: flower: set unlocked flag for flower proto ops Vlad Buslov
2019-02-18 19:27 ` Cong Wang
2019-02-19 10:15 ` Vlad Buslov
2019-02-20 22:36 ` Cong Wang
2019-02-18 19:15 ` [PATCH net-next 00/12] Refactor flower classifier to remove dependency on rtnl lock Cong Wang
2019-02-19 10:00 ` Vlad Buslov
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