On 2013-12-03 13:34, Kim Phillips wrote: > VFIO supports pass-through of devices to user space - for sake > of illustration, say a PCI e1000 device: > > - the e1000 is first unbound from the PCI e1000 driver via sysfs > - the vfio-pci driver is told via new_id that it now handles e1000 devices > - the e1000 is explicitly bound to vfio-pci through sysfs > > However, now we have two drivers in the system that both handle e1000 > devices. A hotplug event could then occur and it is ambiguous as to which > driver will claim the device. The desired semantics is that vfio-pci is > only bound to devices by explicit request in sysfs. This patch makes this > possible by introducing a sysfs_bind_only flag in struct device_driver. > > Signed-off-by: Stuart Yoder <stuart.yo...@freescale.com> > Signed-off-by: Kim Phillips <kim.phill...@linaro.org> > --- > rebased onto 3.13-rc2, and reposted from first submission which > recieved no comments: > > https://lkml.org/lkml/2013/10/11/53 > > drivers/base/dd.c | 5 ++++- > include/linux/device.h | 2 ++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 0605176..b83b16d 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -389,7 +389,7 @@ static int __device_attach(struct device_driver *drv, > void *data) > { > struct device *dev = data; > > - if (!driver_match_device(drv, dev)) > + if (drv->sysfs_bind_only || !driver_match_device(drv, dev)) > return 0; > > return driver_probe_device(drv, dev); > @@ -476,6 +476,9 @@ static int __driver_attach(struct device *dev, void *data) > */ > int driver_attach(struct device_driver *drv) > { > + if (drv->sysfs_bind_only) > + return 0; > + > return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); > } > EXPORT_SYMBOL_GPL(driver_attach); > diff --git a/include/linux/device.h b/include/linux/device.h > index 952b010..ed441d1 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -200,6 +200,7 @@ extern struct klist *bus_get_device_klist(struct bus_type > *bus); > * @owner: The module owner. > * @mod_name: Used for built-in modules. > * @suppress_bind_attrs: Disables bind/unbind via sysfs. > + * @sysfs_bind_only: Only allow bind/unbind via sysfs. > * @of_match_table: The open firmware table. > * @acpi_match_table: The ACPI match table. > * @probe: Called to query the existence of a specific device, > @@ -233,6 +234,7 @@ struct device_driver { > const char *mod_name; /* used for built-in modules */ > > bool suppress_bind_attrs; /* disables bind/unbind via sysfs */ > + bool sysfs_bind_only; /* only allow bind/unbind via sysfs */ > > const struct of_device_id *of_match_table; > const struct acpi_device_id *acpi_match_table; >
I think I only discussed this with Stuart in person at the KVM Forum: Why not deriving the property "sysfs bind only" from the fact that a device does wild-card binding? Are there use cases that benefit from decoupling both features? Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
