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From: Cong Wang <>
To: Vlad Buslov <>
Cc: David Miller <>,
	Linux Kernel Network Developers <>,
	Jamal Hadi Salim <>,
	Jiri Pirko <>,
	LKML <>
Subject: Re: [PATCH net-next v2] net: sched: don't disable bh when accessing action idr
Date: Tue, 22 May 2018 18:10:28 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Mon, May 21, 2018 at 1:03 PM, Vlad Buslov <> 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.

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()...

  parent reply	other threads:[~2018-05-23  1:10 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 [this message]
2018-05-23  6:57           ` Vlad Buslov
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

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