From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
Subject: Re: [PATCH v3 4/4] vfio: enable vfio hotplug by req
	notifier handler
Date: Tue, 2 Oct 2018 15:15:00 +0100
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To: Jeff Guo <jia.guo@intel.com>, stephen@networkplumber.org,
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On 02-Oct-18 1:58 PM, Jeff Guo wrote:
> When device is be hot-unplugged, the vfio kernel module will sent req
> notifier to request user space to release the allocated resources at
> first. After that, vfio kernel module will detect the device disappear,
> and then delete the device in kernel.
> 
> This patch aim to add req notifier processing to enable hotplug for vfio.
> By enable the req notifier monitoring and register the notifier callback,
> when device be hot-unplugged, the hot-unplug handler will be called to
> process hotplug for vfio.
> 
> Signed-off-by: Jeff Guo <jia.guo@intel.com>
> ---
> v3->v2:
> change some code style and typo.
> ---

<snip>

> +/* enable notifier (only enable req now) */
> +static int
> +pci_vfio_enable_notifier(struct rte_pci_device *dev, int vfio_dev_fd)
> +{
> +	int ret;
> +	int fd = -1;
> +
> +	/* set up an eventfd for req notifier */
> +	fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
> +	if (fd < 0) {
> +		RTE_LOG(ERR, EAL, "Cannot set up eventfd, error %i (%s)\n",
> +			errno, strerror(errno));
> +		return -1;
> +	}
> +
> +	dev->req_notifier_handler.fd = fd;
> +	dev->req_notifier_handler.type = RTE_INTR_HANDLE_VFIO_REQ;
> +	dev->req_notifier_handler.vfio_dev_fd = vfio_dev_fd;
> +	ret = rte_intr_callback_register(&dev->req_notifier_handler,
> +					 pci_vfio_req_handler,
> +					 (void *)&dev->device);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "Fail to register req notifier handler.\n");
> +		goto error;

At this point (and further down as well), if we go to error, we've 
already modified the req_notifier_handler data. Do we need to overwrite 
it? Maybe just do these operations on a local struct, and then do a 
memcpy into dev->req_notifier_handler on success?

-- 
Thanks,
Anatoly