From mboxrd@z Thu Jan 1 00:00:00 1970
Return-Path: <thomas@monjalon.net>
Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com
[66.111.4.28]) by dpdk.org (Postfix) with ESMTP id 69EE21B33E
for <dev@dpdk.org>; Tue, 7 Nov 2017 01:26:43 +0100 (CET)
Received: from compute1.internal (compute1.nyi.internal [10.202.2.41])
by mailout.nyi.internal (Postfix) with ESMTP id 1C4F420A62;
Mon, 6 Nov 2017 19:26:43 -0500 (EST)
Received: from frontend2 ([10.202.2.161])
by compute1.internal (MEProxy); Mon, 06 Nov 2017 19:26:43 -0500
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h=
cc:content-transfer-encoding:content-type:date:from:in-reply-to
:message-id:mime-version:references:subject:to:x-me-sender
:x-me-sender:x-sasl-enc; s=mesmtp; bh=tvUaBK/1gR0xtYTrordOG8bO1l
o7/X2wK2QE6A93Mvk=; b=Uu/2H5V51TugTM0jj5tkBsdCE4a8LJ4k+btdJH70Xe
9/p/uqXKGsg6+Zm9Hf70Is8cUh8ZDOszwF/MvpHMgXWlDsjnw0v4wlpwQ75uh0y6
BM5r/tptJs5quf0KR+v3sAhkBkDtGuj5qvAia+432aY19xb/lMIOcq01qlbcu56S
w=
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=
messagingengine.com; h=cc:content-transfer-encoding:content-type
:date:from:in-reply-to:message-id:mime-version:references
:subject:to:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=tvUaBK
/1gR0xtYTrordOG8bO1lo7/X2wK2QE6A93Mvk=; b=YmSgqgfG6WLtRzpv4jrLvl
ygVXhCWKmS1a16MaiYKOVkGkA/lVY9GmR0P3DVnpc7YaA1qR4Kmm1EPoQ55gEMvQ
zjgAzqT0+DHajezyNho+yGIXB1rTZ1tM6DWzaVeI5R/TF8YHlA0Pb2ipqm6KMcxh
EaYM235IEIKjsofoajYGI1Gni9qaC8CMAW8cRCMjBFt2aNUFz1hHq1uwF6W0YW51
G4ZWOxv3aTTWLcqm2X0yg9PZRB3FU0orPxpy2n4YS8TvVeVD/Eiv8WVMmDl5v9iH
e2iV3L0HdxExr8rZJuEjNVd809Zj2JgsRqCDvAiD/VYPKR2lbNvl+8xHQ/WKNrnA
==
X-ME-Sender: <xms:w_0AWp8IHI_nikZJGPMhl0g5L9M6Sy0JU09dqvaV4IqU5XsrkT7OHg>
Received: from xps.localnet (184.203.134.77.rev.sfr.net [77.134.203.184])
by mail.messagingengine.com (Postfix) with ESMTPA id D297D241BE;
Mon, 6 Nov 2017 19:26:42 -0500 (EST)
From: Thomas Monjalon <thomas@monjalon.net>
To: Harry van Haaren <harry.van.haaren@intel.com>
Cc: dev@dpdk.org, Bruce Richardson <bruce.richardson@intel.com>,
pbhagavatula@caviumnetworks.com
Date: Tue, 07 Nov 2017 01:26:42 +0100
Message-ID: <3101300.eJ1rulUoFZ@xps>
In-Reply-To: <20171102094105.GB19712@bricha3-MOBL3.ger.corp.intel.com>
References: <1509450542-123626-1-git-send-email-harry.van.haaren@intel.com>
<1509562081-52763-1-git-send-email-harry.van.haaren@intel.com>
<20171102094105.GB19712@bricha3-MOBL3.ger.corp.intel.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
Subject: Re: [dpdk-dev] [PATCH v2] service: fix race in service on app lcore
function
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
<mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
<mailto:dev-request@dpdk.org?subject=subscribe>
X-List-Received-Date: Tue, 07 Nov 2017 00:26:43 -0000
02/11/2017 10:41, Bruce Richardson:
> On Wed, Nov 01, 2017 at 06:48:01PM +0000, Harry van Haaren wrote:
> > This commit fixes a possible race condition if an application
> > uses the service-cores infrastructure and the function to run
> > a service on an application lcore at the same time.
> >
> > The fix is to change the num_mapped_cores variable to be an
> > atomic variable. This causes concurrent accesses by multiple
> > threads to a service using rte_service_run_iter_on_app_lcore()
> > to detect if another core is currently mapped to the service,
> > and refuses to run if it is not multi-thread safe.
> >
> > The run iteration on app lcore function has two arguments, the
> > service id to run, and if atomics should be used to serialize access
> > to multi-thread unsafe services. This allows applications to choose
> > if they wish to use use the service-cores feature, or if they
> > take responsibility themselves for serializing invoking a service.
> > See doxygen documentation for more details.
> >
> > Two unit tests were added to verify the behaviour of the
> > function to run a service on an application core, testing both
> > a multi-thread safe service, and a multi-thread unsafe service.
> >
> > The doxygen API documentation for the function has been updated
> > to reflect the current and correct behaviour.
> >
> > Fixes: e9139a32f6e8 ("service: add function to run on app lcore")
> >
> > Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
> >
> > ---
> >
> > v2:
> > - Rework function to have parameter that allows the application
> > to select if it requires atomics to be used of it the application
> > wishes to take responsibility for serializing instead.
> >
> This approach seems better to me. I think the function itself might be
> better if you just duplicated a bit more code to reduce the number of
> checks on the serialization variable, but it's readable enough as it is
> now, so
>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Applied, thanks