linux-kernel - Re: [PATCH v4 03/12] vfio_pci: refine vfio_pci_driver reference in vfio

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Date:   Thu, 9 Jan 2020 15:48:19 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Liu Yi L <yi.l.liu@...el.com>
Cc:     kwankhede@...dia.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kevin.tian@...el.com, joro@...tes.org,
        peterx@...hat.com, baolu.lu@...ux.intel.com
Subject: Re: [PATCH v4 03/12] vfio_pci: refine vfio_pci_driver reference in
 vfio_pci.c

On Tue,  7 Jan 2020 20:01:40 +0800
Liu Yi L <yi.l.liu@...el.com> wrote:

> This patch replaces the vfio_pci_driver reference in vfio_pci.c with
> pci_dev_driver(vdev->pdev) which is more helpful to make the functions
> be generic to module types.
> 
> Cc: Kevin Tian <kevin.tian@...el.com>
> Cc: Lu Baolu <baolu.lu@...ux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> ---
>  drivers/vfio/pci/vfio_pci.c | 34 ++++++++++++++++++----------------
>  1 file changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 009d2df..9140f5e5 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -1463,24 +1463,25 @@ static void vfio_pci_reflck_get(struct vfio_pci_reflck *reflck)
>  
>  static int vfio_pci_reflck_find(struct pci_dev *pdev, void *data)
>  {
> -	struct vfio_pci_reflck **preflck = data;
> +	struct vfio_pci_device *vdev = data;
> +	struct vfio_pci_reflck **preflck = &vdev->reflck;
>  	struct vfio_device *device;
> -	struct vfio_pci_device *vdev;
> +	struct vfio_pci_device *tmp;
>  
>  	device = vfio_device_get_from_dev(&pdev->dev);
>  	if (!device)
>  		return 0;
>  
> -	if (pci_dev_driver(pdev) != &vfio_pci_driver) {
> +	if (pci_dev_driver(pdev) != pci_dev_driver(vdev->pdev)) {
>  		vfio_device_put(device);
>  		return 0;
>  	}
>  
> -	vdev = vfio_device_data(device);
> +	tmp = vfio_device_data(device);
>  
> -	if (vdev->reflck) {
> -		vfio_pci_reflck_get(vdev->reflck);
> -		*preflck = vdev->reflck;
> +	if (tmp->reflck) {
> +		vfio_pci_reflck_get(tmp->reflck);
> +		*preflck = tmp->reflck;

Seems we can do away with preflck entirely with this refactor, this
simply becomes vdev->reflck = tmp->reflck.  Thanks,

Alex

>  		vfio_device_put(device);
>  		return 1;
>  	}
> @@ -1497,7 +1498,7 @@ static int vfio_pci_reflck_attach(struct vfio_pci_device *vdev)
>  
>  	if (pci_is_root_bus(vdev->pdev->bus) ||
>  	    vfio_pci_for_each_slot_or_bus(vdev->pdev, vfio_pci_reflck_find,
> -					  &vdev->reflck, slot) <= 0)
> +					  vdev, slot) <= 0)
>  		vdev->reflck = vfio_pci_reflck_alloc();
>  
>  	mutex_unlock(&reflck_lock);
> @@ -1522,6 +1523,7 @@ static void vfio_pci_reflck_put(struct vfio_pci_reflck *reflck)
>  
>  struct vfio_devices {
>  	struct vfio_device **devices;
> +	struct vfio_pci_device *vdev;
>  	int cur_index;
>  	int max_index;
>  };
> @@ -1530,7 +1532,7 @@ static int vfio_pci_get_unused_devs(struct pci_dev *pdev, void *data)
>  {
>  	struct vfio_devices *devs = data;
>  	struct vfio_device *device;
> -	struct vfio_pci_device *vdev;
> +	struct vfio_pci_device *tmp;
>  
>  	if (devs->cur_index == devs->max_index)
>  		return -ENOSPC;
> @@ -1539,15 +1541,15 @@ static int vfio_pci_get_unused_devs(struct pci_dev *pdev, void *data)
>  	if (!device)
>  		return -EINVAL;
>  
> -	if (pci_dev_driver(pdev) != &vfio_pci_driver) {
> +	if (pci_dev_driver(pdev) != pci_dev_driver(devs->vdev->pdev)) {
>  		vfio_device_put(device);
>  		return -EBUSY;
>  	}
>  
> -	vdev = vfio_device_data(device);
> +	tmp = vfio_device_data(device);
>  
>  	/* Fault if the device is not unused */
> -	if (vdev->refcnt) {
> +	if (tmp->refcnt) {
>  		vfio_device_put(device);
>  		return -EBUSY;
>  	}
> @@ -1574,7 +1576,7 @@ static int vfio_pci_get_unused_devs(struct pci_dev *pdev, void *data)
>   */
>  static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev)
>  {
> -	struct vfio_devices devs = { .cur_index = 0 };
> +	struct vfio_devices devs = { .vdev = vdev, .cur_index = 0 };
>  	int i = 0, ret = -EINVAL;
>  	bool slot = false;
>  	struct vfio_pci_device *tmp;
> @@ -1637,7 +1639,7 @@ static void __exit vfio_pci_cleanup(void)
>  	vfio_pci_uninit_perm_bits();
>  }
>  
> -static void __init vfio_pci_fill_ids(char *ids)
> +static void __init vfio_pci_fill_ids(char *ids, struct pci_driver *driver)
>  {
>  	char *p, *id;
>  	int rc;
> @@ -1665,7 +1667,7 @@ static void __init vfio_pci_fill_ids(char *ids)
>  			continue;
>  		}
>  
> -		rc = pci_add_dynid(&vfio_pci_driver, vendor, device,
> +		rc = pci_add_dynid(driver, vendor, device,
>  				   subvendor, subdevice, class, class_mask, 0);
>  		if (rc)
>  			pr_warn("failed to add dynamic id [%04x:%04x[%04x:%04x]] class %#08x/%08x (%d)\n",
> @@ -1692,7 +1694,7 @@ static int __init vfio_pci_init(void)
>  	if (ret)
>  		goto out_driver;
>  
> -	vfio_pci_fill_ids(ids);
> +	vfio_pci_fill_ids(ids, &vfio_pci_driver);
>  
>  	return 0;
>