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Subject: Re: [PATCH v9 16/17] vduse: Introduce VDUSE - vDPA Device in
 Userspace
To:     Dan Carpenter <dan.carpenter@oracle.com>,
        Xie Yongji <xieyongji@bytedance.com>
Cc:     mst@redhat.com, stefanha@redhat.com, sgarzare@redhat.com,
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        xiaodong.liu@intel.com, songmuchun@bytedance.com,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
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References: <20210713084656.232-1-xieyongji@bytedance.com>
 <20210713084656.232-17-xieyongji@bytedance.com> <20210713132741.GM1954@kadam>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <c42979dd-331f-4af5-fda6-18d80f22be2d@redhat.com>
Date:   Wed, 14 Jul 2021 10:54:08 +0800
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?? 2021/7/13 ????9:27, Dan Carpenter д??:
> On Tue, Jul 13, 2021 at 04:46:55PM +0800, Xie Yongji wrote:
>> +static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name)
>> +{
>> +	struct vduse_vdpa *vdev;
>> +	int ret;
>> +
>> +	if (dev->vdev)
>> +		return -EEXIST;
>> +
>> +	vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, dev->dev,
>> +				 &vduse_vdpa_config_ops, name, true);
>> +	if (!vdev)
>> +		return -ENOMEM;
> This should be an IS_ERR() check instead of a NULL check.


Yes.


>
> The vdpa_alloc_device() macro is doing something very complicated but
> I'm not sure what.  It calls container_of() and that looks buggy until
> you spot the BUILD_BUG_ON_ZERO() compile time assert which ensures that
> the container_of() is a no-op.
>
> Only one of the callers checks for error pointers correctly so maybe
> it's too complicated or maybe there should be better documentation.


We need better documentation for this macro and fix all the buggy callers.

Yong Ji, want to do that?

Thanks


>
> regards,
> dan carpenter
>