On 14/02/2019 15:54, Cornelia Huck wrote:
On Thu, 14 Feb 2019 14:51:01 +0100
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
Libudev relies on having a subsystem link for non-root devices. To
avoid libudev (and potentially other userspace tools) choking on the
matrix device let us introduce a vfio_ap bus and with that the vfio_ap
bus subsytem, and make the matrix device reside within it.
How does libudev choke on this? It feels wrong to introduce a bus that
basically does nothing...
Christian answered this in another thread, so I don't answer.
We restrict the number of allowed devices to a single one.
...snip...
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -24,8 +24,9 @@ MODULE_LICENSE("GPL v2");
static struct ap_driver vfio_ap_drv;
-static struct device_type vfio_ap_dev_type = {
- .name = VFIO_AP_DEV_TYPE_NAME,
+struct matrix_driver {
+ struct device_driver drv;
+ int device_count;
This counter basically ensures that at most one device may bind with
this driver... you'd still have that device on the bus, though.
yes, this is what is wanted: this driver can only support one device.
May be another matrix driver can support one or more other devices.
I should update comment message my be.
};
struct ap_matrix_dev *matrix_dev;
- matrix_dev->device.type = &vfio_ap_dev_type;
dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
matrix_dev->device.parent = root_device;
+ matrix_dev->device.bus = &matrix_bus;
matrix_dev->device.release = vfio_ap_matrix_dev_release;
- matrix_dev->device.driver = &vfio_ap_drv.driver;
+ matrix_dev->vfio_ap_drv = &vfio_ap_drv;
Can't you get that structure through matrix_dev->device.driver instead
when you need it in the function below?
Not anymore.
We have two different drivers and devices
matrix_drv <-> matrix_dev
and
vfio_ap_drv <-> ap_devices
The driver behind the matrix_dev->dev->driver is matrix_drv
what is needed here is vfio_ap_drv.
ret = device_register(&matrix_dev->device);
if (ret)
goto matrix_reg_err;
+ ret = driver_register(&matrix_driver.drv);
+ if (ret)
+ goto matrix_drv_err;
+
As you already have several structures that can be registered exactly
once (the root device, the bus, the driver, ...), you can already be
sure that there's only one device on the bus, can't you?
hum, no I don't think so, no device can register before this module is
loaded, but what does prevent a device to register later from another
module?
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
