From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Subject: Re: [PATCH 1/2] vhost: reference count fix for
	nb_started_ports
Date: Thu, 29 Dec 2016 16:51:32 +0800
Message-ID: <20161229085132.GC21789@yliu-dev.sh.intel.com>
References: <1482959452-18486-1-git-send-email-ciwillia@brocade.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: dev@dpdk.org, mtetsuyah@gmail.com, Wen Chiu <wchiu@brocade.com>
To: "Charles (Chas) Williams" <ciwillia@brocade.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mga09.intel.com (mga09.intel.com [134.134.136.24])
 by dpdk.org (Postfix) with ESMTP id 23DE72C4F
 for <dev@dpdk.org>; Thu, 29 Dec 2016 09:49:47 +0100 (CET)
Content-Disposition: inline
In-Reply-To: <1482959452-18486-1-git-send-email-ciwillia@brocade.com>
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>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Wed, Dec 28, 2016 at 04:10:51PM -0500, Charles (Chas) Williams wrote:
> From: Wen Chiu <wchiu@brocade.com>
> 
> Only increment and decrement nb_started_ports on the first and last
> device start and stop.  Otherwise, nb_started_ports can become negative
> if a device is stopped multiple times.

How could you be able to stop dev (precisely, invoke eth_dev_stop)
multiple times, judging that eth_dev_stop() will be invoked once
only?

    void
    rte_eth_dev_stop(uint8_t port_id)
    {
            struct rte_eth_dev *dev;
    
            RTE_ETH_VALID_PORTID_OR_RET(port_id);
            dev = &rte_eth_devices[port_id];
    
            RTE_FUNC_PTR_OR_RET(*dev->dev_ops->dev_stop);
    
==>         if (dev->data->dev_started == 0) {
                    RTE_PMD_DEBUG_TRACE("Device with port_id=%" PRIu8
                            " already stopped\n",
                            port_id);
                    return;
            }
    
==>         dev->data->dev_started = 0;
            (*dev->dev_ops->dev_stop)(dev);
    }

Multiple threads?

	--yliu