Messages in this thread | | | Subject | Re: [PATCH v3 1/9] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem | From | Pierre Morel <> | Date | Thu, 14 Feb 2019 18:36:46 +0100 |
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On 14/02/2019 17:57, Cornelia Huck wrote: > On Thu, 14 Feb 2019 16:47:30 +0100 Pierre Morel > <pmorel@linux.ibm.com> wrote: > >> On 14/02/2019 15:54, Cornelia Huck wrote: >>> On Thu, 14 Feb 2019 14:51:01 +0100 Pierre Morel >>> <pmorel@linux.ibm.com> wrote: > >>>> +++ 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. > > Wait, we had tacked a driver for ap devices unto a matrix device, > which is not on the ap bus?
...yes -(
> Maybe that's what trips libudev? > > (And reading further in the current code, it seems we clear that > structure _after_ the matrix device had been setup, so how can that > even work? Where am I confused?)
On device_register there were no bus, so the core just do not look for a driver and this field was nor tested nor overwritten.
> >> >>> >>>> >>>> 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? > > Not unless you export the interface, I guess. >
:) definitively right thanks, this will simplify the code in the next version. I will take the patch away from this series to get the way to stable as Christian requested.
Regards, Pierre
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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