linux-kernel - Re: [PATCH] net: sched: don't disable bh when accessing action idr

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Message-ID: <vbflgcgnece.fsf@reg-r-vrt-018-180.mtr.labs.mlnx>
Date:   Sat, 19 May 2018 13:12:49 +0300
From:   Vlad Buslov <vladbu@...lanox.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        David Miller <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: sched: don't disable bh when accessing action idr


On Sat 19 May 2018 at 02:59, Cong Wang <xiyou.wangcong@...il.com> wrote:
> On Fri, May 18, 2018 at 8:45 AM, Vlad Buslov <vladbu@...lanox.com> wrote:
>> Underlying implementation of action map has changed and doesn't require
>> disabling bh anymore. Replace all action idr spinlock usage with regular
>> calls that do not disable bh.
>
> Please explain explicitly why it is not required, don't let people
> dig, this would save everyone's time.

Underlying implementation of actions lookup has changed from hashtable
to idr. Every current action implementation just calls act_api lookup
function instead of implementing its own lookup. I asked author of idr
change if there is a reason to continue to use _bh versions and he
replied that he just left them as-is.

>
> Also, this should be targeted for net-next, right?

Right.

>
> Thanks.