LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Vlad Buslov <vladbu@mellanox.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: David Miller <davem@davemloft.net>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Jiri Pirko <jiri@resnulli.us>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next v2] net: sched: don't disable bh when accessing action idr
Date: Wed, 23 May 2018 09:57:34 +0300	[thread overview]
Message-ID: <vbfy3gaj1up.fsf@reg-r-vrt-018-180.mtr.labs.mlnx> (raw)
In-Reply-To: <CAM_iQpVMFSxnN6dEi0U4=aw7s7TcJ88ShiNTDXcoRUVL82jTZw@mail.gmail.com>


On Wed 23 May 2018 at 01:10, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Mon, May 21, 2018 at 1:03 PM, Vlad Buslov <vladbu@mellanox.com> wrote:
>> Initial net_device implementation used ingress_lock spinlock to synchronize
>> ingress path of device. This lock was used in both process and bh context.
>> In some code paths action map lock was obtained while holding ingress_lock.
>> Commit e1e992e52faa ("[NET_SCHED] protect action config/dump from irqs")
>> modified actions to always disable bh, while using action map lock, in
>> order to prevent deadlock on ingress_lock in softirq. This lock was removed
>> from net_device, so disabling bh, while accessing action map, is no longer
>> necessary.
>>
>> Replace all action idr spinlock usage with regular calls that do not
>> disable bh.
>
> While your patch is probably fine, the above justification seems not.

Sorry if I missed something. My justification is based on commit
description that added bh disable in subject code.

>
> In the past, tc actions could be released in BH context because tc
> filters use call_rcu(). However, I moved them to a workqueue recently.
> So before my change I don't think you can remove the BH protection,
> otherwise race with idr_remove()...

Found commit series that you described. Will modify commit message
accordingly.

Thanks,
Vlad

  reply	other threads:[~2018-05-23  7:00 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18 15:45 [PATCH] net: sched: don't disable bh when accessing action idr Vlad Buslov
2018-05-19  2:59 ` Cong Wang
2018-05-19 10:12   ` Vlad Buslov
2018-05-20  3:02     ` David Miller
2018-05-21 20:03       ` [PATCH net-next v2] " Vlad Buslov
2018-05-22 12:50         ` Jamal Hadi Salim
2018-05-23  1:10         ` Cong Wang
2018-05-23  6:57           ` Vlad Buslov [this message]
2018-05-23  7:32         ` Jiri Pirko
2018-05-23  8:52           ` [PATCH net-next v3] " Vlad Buslov
2018-05-23 23:14             ` Cong Wang
2018-05-24 16:54               ` Vlad Buslov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=vbfy3gaj1up.fsf@reg-r-vrt-018-180.mtr.labs.mlnx \
    --to=vladbu@mellanox.com \
    --cc=davem@davemloft.net \
    --cc=jhs@mojatatu.com \
    --cc=jiri@resnulli.us \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=xiyou.wangcong@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).