after

/*
 * num_vfs > 0; number of VFs to enable
 * num_vfs = 0; disable all VFs
 *
 * Note: SRIOV spec doesn't allow partial VF
 *       disable, so it's all or none.
 */
static ssize_t sriov_numvfs_store(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf, size_t count)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        int ret;
        u16 num_vfs;

        ret = kstrtou16(buf, 0, &num_vfs);
        if (ret < 0)
                return ret;

        if (num_vfs > pci_sriov_get_totalvfs(pdev))
                return -ERANGE;

        if (num_vfs == pdev->sriov->num_VFs)
                return count;           /* no change */

        /* is PF driver loaded w/callback */
        if (!pdev->driver || !pdev->driver->sriov_configure) {
                dev_info(&pdev->dev, "Driver doesn't support SRIOV configuration via sysfs\n");
                return -ENOSYS;
        }

        if (num_vfs == 0) {
                /* disable VFs */
                ret = pdev->driver->sriov_configure(pdev, 0);
                if (ret < 0)
                        return ret;
                return count;
        }

        /* enable VFs */
        if (pdev->sriov->num_VFs) {
                dev_warn(&pdev->dev, "%d VFs already enabled. Disable before enabling %d VFs\n",
                         pdev->sriov->num_VFs, num_vfs);
                return -EINVAL;
        }

        ret = pdev->driver->sriov_configure(pdev, num_vfs);
        if (ret < 0)
                return ret;

        if (ret != num_vfs)
                dev_warn(&pdev->dev, "%d VFs requested; only %d enabled\n",
                         num_vfs, ret);

        return count;
}