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Date:      Mon, 5 Aug 2013 22:16:20 +0200
From:      Luigi Rizzo <rizzo@iet.unipi.it>
To:        Adrian Chadd <adrian@freebsd.org>
Cc:        FreeBSD current mailing list <current@freebsd.org>, Bryan Venteicher <bryanv@daemoninthecloset.org>, Navdeep Parhar <np@freebsd.org>, net@freebsd.org, Giuseppe Lettieri <g.lettieri@iet.unipi.it>, Jack Vogel <jfvogel@gmail.com>
Subject:   Re: [net] protecting interfaces from races between control and data ?
Message-ID:  <CA%2BhQ2%2Bi7RHqy3ex9qeU_7-4Ed4zBRwumCrFO7OT_j8VKWZp%2B6g@mail.gmail.com>
In-Reply-To: <CAJ-VmomtmPcN_ebV2AEiRz9sVyYRcvo9Kt0HvhazSCuHpGk3Ew@mail.gmail.com>
References:  <20130805082307.GA35162@onelab2.iet.unipi.it> <2034715395.855.1375714772487.JavaMail.root@daemoninthecloset.org> <CAJ-VmokT6YKPR7CXsoCavEmWv3W8urZu4eBVgKWaj9iMaVJFZg@mail.gmail.com> <CA%2BhQ2%2BhuoCCweq7fjoYmH3nyhmhb5DzukEdPSMtaJEWa8Ft0JQ@mail.gmail.com> <51FFDD1E.1000206@FreeBSD.org> <CAJ-Vmo=Q9AqdBJ0%2B4AiX4%2BWreYuZx6VGGYw=MZ4XhMB1P2yMww@mail.gmail.com> <CA%2BhQ2%2BgZTGmrBKTOAeFnNma4DQXbAy_y8NZrovpWqm_5BJTWhQ@mail.gmail.com> <CAFOYbckJaZYQj2D4k41Nmjm9urue9_CDcdQ3yhRddWx0SzXE6g@mail.gmail.com> <CA%2BhQ2%2BhAcyi=uFcOLV1YNMfDAmdhJoTtqtgpb=R_-RKSmWX9FQ@mail.gmail.com> <CAJ-VmomtmPcN_ebV2AEiRz9sVyYRcvo9Kt0HvhazSCuHpGk3Ew@mail.gmail.com>

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On Mon, Aug 5, 2013 at 8:19 PM, Adrian Chadd <adrian@freebsd.org> wrote:

> No, brian said two things:
>
> * the flag, protected by the core lock
> * per-queue flags
>

i see no mentions on per-queue flags on his email.
This is the relevant part

------------

What I've done in my drivers is:
  * Lock the core mutex
  * Clear IFF_DRV_RUNNING
  * Lock/unlock each queue's lock

The various Rx/Tx queue functions check for IFF_DRV_RUNNING after
(re)acquiring their queue lock. See at vtnet_stop_rendezvous() at
[1] for an example.

[1]
http://svnweb.freebsd.org/base/user/bryanv/vtnetmq/sys/dev/virtio/network/if_vtnet.c?revision=252451&view=markup

-----------------


>
>
>
> -adrian
>



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