Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH vhost next 06/10] vdpa: Add means to communicate vq status
 on get_vq_state
To:     Eli Cohen <eli@mellanox.com>
Cc:     mst@redhat.com, virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, shahafs@mellanox.com,
        saeedm@mellanox.com, Parav Pandit <parav@mellanox.com>
References: <20200716072327.5359-1-eli@mellanox.com>
 <20200716072327.5359-7-eli@mellanox.com>
 <cb9bced7-1a7e-150a-875c-1b75f77ee853@redhat.com>
 <20200716082116.GA182860@mtl-vdi-166.wap.labs.mlnx>
 <296e6fcb-946c-f577-2e22-46528f78fda9@redhat.com>
 <20200716102533.GB186790@mtl-vdi-166.wap.labs.mlnx>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <0ed28d74-cb0c-89af-61dd-9256e8bb2328@redhat.com>
Date:   Mon, 20 Jul 2020 12:13:24 +0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20200716102533.GB186790@mtl-vdi-166.wap.labs.mlnx>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 2020/7/16 下午6:25, Eli Cohen wrote:
> On Thu, Jul 16, 2020 at 05:35:18PM +0800, Jason Wang wrote:
>> On 2020/7/16 下午4:21, Eli Cohen wrote:
>>> On Thu, Jul 16, 2020 at 04:11:00PM +0800, Jason Wang wrote:
>>>> On 2020/7/16 下午3:23, Eli Cohen wrote:
>>>>> Currently, get_vq_state() is used only to pass the available index value
>>>>> of a vq. Extend the struct to return status on the VQ to the caller.
>>>>> For now, define VQ_STATE_NOT_READY. In the future it will be extended to
>>>>> include other infomration.
>>>>>
>>>>> Modify current vdpa driver to update this field.
>>>>>
>>>>> Reviewed-by: Parav Pandit<parav@mellanox.com>
>>>>> Signed-off-by: Eli Cohen<eli@mellanox.com>
>>>> What's the difference between this and get_vq_ready()?
>>>>
>>>> Thanks
>>>>
>>> There is no difference. It is just a way to communicate a problem to
>>> with the state of the VQ back to the caller. This is not available now.
>>> I think an asynchronous is preferred but that is not available
>>> currently.
>>
>> I still don't see the reason, maybe you can give me an example?
>>
>>
> My intention was to provide a mechainsm to return meaningful information
> on the state of the vq. For example, when you fail to get the state of
> the VQ.
>
> Maybe I could just change the prototype of the function to return int
> and the driver could put an error if it has trouble returning the vq
> state.


That's fine.

Thanks