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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 27 Jul 2015 13:35:57 +0200
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Subject: Re: [Qemu-devel] [PATCH] vhost-scsi: Fix mask index err in
	vhost_scsi_start
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To: Gonglei <arei.gonglei@huawei.com>, qemu-devel@nongnu.org
Cc: Lu Lina <lina.lulina@huawei.com>



On 27/07/2015 13:11, Gonglei wrote:
> On 2015/7/27 18:20, Paolo Bonzini wrote:
>>
>>
>> On 27/07/2015 08:25, arei.gonglei@huawei.com wrote:
>>> +++ b/hw/scsi/vhost-scsi.c
>>> @@ -117,7 +117,7 @@ static int vhost_scsi_start(VHostSCSI *s)
>>>       * enabling/disabling irqfd.
>>>       */
>>>      for (i = 0; i < s->dev.nvqs; i++) {
>>> -        vhost_virtqueue_mask(&s->dev, vdev, i, false);
>>> +        vhost_virtqueue_mask(&s->dev, vdev, s->dev.vq_index + i, false);
>>>      }
>>>  
>>>      return ret;
>>
>> Is this fixing an actual bug, or just using the API correctly?
>> s->dev.vq_index is always 0, right?
>>
> Yes.  At present, we found that s->dev.vq_index is always 0.

Ok, then I've applied the patch with this commit message:

vhost_virtqueue_mask takes an "absolute" virtqueue index, while the
code looks like it's passing an index that is relative to
s->dev.vq_index.  In reality, s->dev.vq_index is always zero, so
this patch does not make any difference, but the code is clearer.

Paolo