Re: [Qemu-devel] [PATCH v9 2/7] virtio-pmem: Add virtio pmem driver

From: Pankaj Gupta <pagupta@redhat.com>
To: "Jakub Staroń" <jstaron@google.com>
Cc: cohuck@redhat.com, jack@suse.cz, kvm@vger.kernel.org,
	mst@redhat.com, david@fromorbit.com, qemu-devel@nongnu.org,
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	riel@surriel.com, yuval shaia <yuval.shaia@oracle.com>,
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	dan j williams <dan.j.williams@intel.com>,
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	xiaoguangrong eric <xiaoguangrong.eric@gmail.com>,
	darrick wong <darrick.wong@oracle.com>,
	rjw@rjwysocki.net, linux-kernel@vger.kernel.org,
	linux-xfs@vger.kernel.o
Subject: Re: [Qemu-devel] [PATCH v9 2/7] virtio-pmem: Add virtio pmem driver
Date: Fri, 17 May 2019 01:35:58 -0400 (EDT)	[thread overview]
Message-ID: <1954162775.29408078.1558071358974.JavaMail.zimbra__24444.3303252169$1558071374$gmane$org@redhat.com> (raw)
In-Reply-To: <c06514fd-8675-ba74-4b7b-ff0eb4a91605@google.com>

Hi Jakub,

> 
> On 5/14/19 7:54 AM, Pankaj Gupta wrote:
> > +		if (!list_empty(&vpmem->req_list)) {
> > +			req_buf = list_first_entry(&vpmem->req_list,
> > +					struct virtio_pmem_request, list);
> > +			req_buf->wq_buf_avail = true;
> > +			wake_up(&req_buf->wq_buf);
> > +			list_del(&req_buf->list);
> Yes, this change is the right one, thank you!

Thank you for the confirmation.

> 
> > +	 /*
> > +	  * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual
> > +	  * queue does not have free descriptor. We add the request
> > +	  * to req_list and wait for host_ack to wake us up when free
> > +	  * slots are available.
> > +	  */
> > +	while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req,
> > +					GFP_ATOMIC)) == -ENOSPC) {
> > +
> > +		dev_err(&vdev->dev, "failed to send command to virtio pmem" \
> > +			"device, no free slots in the virtqueue\n");
> > +		req->wq_buf_avail = false;
> > +		list_add_tail(&req->list, &vpmem->req_list);
> > +		spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
> > +
> > +		/* A host response results in "host_ack" getting called */
> > +		wait_event(req->wq_buf, req->wq_buf_avail);
> > +		spin_lock_irqsave(&vpmem->pmem_lock, flags);
> > +	}
> > +	err1 = virtqueue_kick(vpmem->req_vq);
> > +	spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
> > +
> > +	/*
> > +	 * virtqueue_add_sgs failed with error different than -ENOSPC, we can't
> > +	 * do anything about that.
> > +	 */
> > +	if (err || !err1) {
> > +		dev_info(&vdev->dev, "failed to send command to virtio pmem device\n");
> > +		err = -EIO;
> > +	} else {
> > +		/* A host repsonse results in "host_ack" getting called */
> > +		wait_event(req->host_acked, req->done);
> > +		err = req->ret;
> > +I confirm that the failures I was facing with the `-ENOSPC` error path are
> > not present in v9.

Can I take it your reviewed/acked-by? or tested-by tag? for the virtio patch :)

Thank you,
Pankaj

> 
> Best,
> Jakub Staron
> 
> 