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SubjectRe: [PATCH v9 10/22] s390: vfio-ap: sysfs interfaces to configure adapters
On Mon, 13 Aug 2018 17:48:07 -0400
Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:

> +/**
> + * assign_adapter_store
> + *
> + * @dev: the matrix device
> + * @attr: a mediated matrix device attribute
> + * @buf: a buffer containing the adapter ID (APID) to be assigned
> + * @count: the number of bytes in @buf
> + *
> + * Parses the APID from @buf and assigns it to the mediated matrix device.
> + *
> + * Returns the number of bytes processed if the APID is valid; otherwise returns
> + * an error.
> + */
> +static ssize_t assign_adapter_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int ret = 0;

You don't need to initialize this to 0, as kstrtoul will set it in any
case.

> + unsigned long apid;
> + struct mdev_device *mdev = mdev_from_dev(dev);
> + struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> + unsigned long max_apid = matrix_mdev->matrix.apm_max;
> +
> + ret = kstrtoul(buf, 0, &apid);
> + if (ret)
> + return ret;
> + if (apid > max_apid)
> + return -EINVAL;
> +
> + /* Set the bit in the AP mask (APM) corresponding to the AP adapter
> + * number (APID). The bits in the mask, from most significant to least
> + * significant bit, correspond to APIDs 0-255.
> + */
> + mutex_lock(&matrix_dev.lock);
> +
> + ret = vfio_ap_mdev_verify_queues_reserved_for_apid(matrix_mdev, apid);

That function name really is a mouthful :) I don't have any better
suggestions, though.

> + if (ret)
> + goto done;
> +
> + set_bit_inv(apid, matrix_mdev->matrix.apm);
> +
> + ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
> + if (ret)
> + goto share_err;
> +
> + ret = count;
> + goto done;
> +
> +share_err:
> + clear_bit_inv(apid, matrix_mdev->matrix.apm);
> +done:
> + mutex_unlock(&matrix_dev.lock);
> +
> + return ret;
> +}
> +static DEVICE_ATTR_WO(assign_adapter);
> +
> +/**
> + * unassign_adapter_store
> + *
> + * @dev: the matrix device
> + * @attr: a mediated matrix device attribute
> + * @buf: a buffer containing the adapter ID (APID) to be assigned
> + * @count: the number of bytes in @buf
> + *
> + * Parses the APID from @buf and unassigns it from the mediated matrix device.
> + * The APID must be a valid value

A valid value, but not necessarily assigned, right?

> + *
> + * Returns the number of bytes processed if the APID is valid; otherwise returns
> + * an error.
> + */
> +static ssize_t unassign_adapter_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int ret;
> + unsigned long apid;
> + struct mdev_device *mdev = mdev_from_dev(dev);
> + struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> +
> + ret = kstrtoul(buf, 0, &apid);
> + if (ret)
> + return ret;
> +
> + if (apid > matrix_mdev->matrix.apm_max)
> + return -EINVAL;
> +
> + mutex_lock(&matrix_dev.lock);
> + clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
> + mutex_unlock(&matrix_dev.lock);
> +
> + return count;
> +}
> +DEVICE_ATTR_WO(unassign_adapter);

In general, looks good to me.

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