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Subject: Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops
To:     Jason Wang <jasowang@redhat.com>, kvm@vger.kernel.org,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
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Cc:     virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        cohuck@redhat.com, maxime.coquelin@redhat.com,
        cunming.liang@intel.com, zhihong.wang@intel.com,
        rob.miller@broadcom.com, xiao.w.wang@intel.com,
        haotian.wang@sifive.com, zhenyuw@linux.intel.com,
        zhi.a.wang@intel.com, jani.nikula@linux.intel.com,
        joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com,
        airlied@linux.ie, daniel@ffwll.ch, farman@linux.ibm.com,
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        heiko.carstens@de.ibm.com, gor@linux.ibm.com,
        borntraeger@de.ibm.com, akrowiak@linux.ibm.com,
        freude@linux.ibm.com, lingshan.zhu@intel.com, idos@mellanox.com,
        eperezma@redhat.com, lulu@redhat.com, parav@mellanox.com,
        christophe.de.dinechin@gmail.com, kevin.tian@intel.com,
        stefanha@redhat.com
References: <20191023130752.18980-1-jasowang@redhat.com>
 <20191023130752.18980-5-jasowang@redhat.com>
 <df1eb77c-d159-da11-bb8f-df2c19089ac6@linux.intel.com>
 <14410ac9-cc01-185a-5dcf-7f6c78aefd65@redhat.com>
From:   Zhu Lingshan <lingshan.zhu@linux.intel.com>
Message-ID: <bc6b2565-b0b6-bf0a-812f-d0bb157be086@linux.intel.com>
Date:   Wed, 30 Oct 2019 15:36:24 +0800
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On 10/29/2019 6:42 PM, Jason Wang wrote:
> On 2019/10/29 下午3:42, Zhu Lingshan wrote:
>>> +    void (*set_status)(struct mdev_device *mdev, u8 status);
>> Hi Jason
>>
>> Is it possible to make set_status() return an u8 or bool, because this
>> may fail in real hardware. Without a returned code, I am not sure
>> whether it is a good idea to set the status | NEED_RESET when fail.
>>
>> Thanks,
>> BR
>> Zhu Lingshan
>
> Hi:
>
>
> It's possible but I'm not sure whether any user will care about it. E.g
> see virtio_add_status():
>
> void virtio_add_status(struct virtio_device *dev, unsigned int status)
> {
>      might_sleep();
>      dev->config->set_status(dev, dev->config->get_status(dev) | status);
> }
> EXPORT_SYMBOL_GPL(virtio_add_status);
>
> And I believe how it work should be:
>
> virtio_add_status(xyz);
>
> status = virtio_get_status();
>
> if (!(status & xyz))
>
>      error;
>
> Thanks
>
Thanks Jason, then I believe upper layer can handle this well.
>