linux-kernel - Re: [PATCH V2 2/2] virtio_pmem: set device ready in probe()

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Date:   Mon, 27 Jun 2022 03:59:52 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     dan.j.williams@...el.com, vishal.l.verma@...el.com,
        dave.jiang@...el.com, ira.weiny@...el.com, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, pankaj.gupta@....com
Subject: Re: [PATCH V2 2/2] virtio_pmem: set device ready in probe()

On Mon, Jun 27, 2022 at 02:29:41PM +0800, Jason Wang wrote:
> The NVDIMM region could be available before the virtio_device_ready()
> that is called by virtio_dev_probe(). This means the driver tries to
> use device before DRIVER_OK which violates the spec, fixing this by

s/fixing this by/to fix this/

> set device ready before the nvdimm_pmem_region_create().
> 
> Note that this means the virtio_pmem_host_ack() could be triggered
> before the creation of the nd region, this is safe since the
> virtio_pmem_host_ack() since pmem_lock has been initialized and

can't parse this sentence, since repeated twice confuses me

> whether or not any available buffer is added before is validated.
> 
> Fixes 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver")
> Acked-by: Pankaj Gupta <pankaj.gupta@....com>
> Signed-off-by: Jason Wang <jasowang@...hat.com>
> ---
> Changes since v1:
> - Remove some comments per Dan
> ---
>  drivers/nvdimm/virtio_pmem.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c
> index 48f8327d0431..20da455d2ef6 100644
> --- a/drivers/nvdimm/virtio_pmem.c
> +++ b/drivers/nvdimm/virtio_pmem.c
> @@ -84,6 +84,12 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
>  	ndr_desc.provider_data = vdev;
>  	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
>  	set_bit(ND_REGION_ASYNC, &ndr_desc.flags);
> +	/*
> +	 * The NVDIMM region could be available before the
> +	 * virtio_device_ready() that is called by
> +	 * virtio_dev_probe(), so we set device ready here.
> +	 */
> +	virtio_device_ready(vdev);
>  	nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc);
>  	if (!nd_region) {
>  		dev_err(&vdev->dev, "failed to create nvdimm region\n");
> @@ -92,6 +98,7 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
>  	}
>  	return 0;
>  out_nd:
> +	virtio_reset_device(vdev);
>  	nvdimm_bus_unregister(vpmem->nvdimm_bus);
>  out_vq:
>  	vdev->config->del_vqs(vdev);
> -- 
> 2.25.1