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    SubjectRe: [PATCH v2 2/6] driver core: Add common support to skip probe for un-authorized devices
    On Wed, Sep 29, 2021 at 06:05:07PM -0700, Kuppuswamy Sathyanarayanan wrote:
    > While the common case for device-authorization is to skip probe of
    > unauthorized devices, some buses may still want to emit a message on
    > probe failure (Thunderbolt), or base probe failures on the
    > authorization status of a related device like a parent (USB). So add
    > an option (has_probe_authorization) in struct bus_type for the bus
    > driver to own probe authorization policy.
    >
    > Reviewed-by: Dan Williams <dan.j.williams@intel.com>
    > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>



    So what e.g. the PCI patch
    https://lore.kernel.org/all/CACK8Z6E8pjVeC934oFgr=VB3pULx_GyT2NkzAogdRQJ9TKSX9A@mail.gmail.com/
    actually proposes is a list of
    allowed drivers, not devices. Doing it at the device level
    has disadvantages, for example some devices might have a legacy
    unsafe driver, or an out of tree driver. It also does not
    address drivers that poke at hardware during init.

    Accordingly, I think the right thing to do is to skip
    driver init for disallowed drivers, not skip probe
    for specific devices.


    > ---
    > drivers/base/dd.c | 5 +++++
    > drivers/thunderbolt/domain.c | 1 +
    > drivers/usb/core/driver.c | 1 +
    > include/linux/device/bus.h | 4 ++++
    > 4 files changed, 11 insertions(+)
    >
    > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
    > index 68ea1f949daa..0cd03ac7d3b1 100644
    > --- a/drivers/base/dd.c
    > +++ b/drivers/base/dd.c
    > @@ -544,6 +544,11 @@ static int really_probe(struct device *dev, struct device_driver *drv)
    > !drv->suppress_bind_attrs;
    > int ret;
    >
    > + if (!dev->authorized && !dev->bus->has_probe_authorization) {
    > + dev_dbg(dev, "Device is not authorized\n");
    > + return -ENODEV;
    > + }
    > +
    > if (defer_all_probes) {
    > /*
    > * Value of defer_all_probes can be set only by
    > diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c
    > index 3e39686eff14..6de8a366b796 100644
    > --- a/drivers/thunderbolt/domain.c
    > +++ b/drivers/thunderbolt/domain.c
    > @@ -321,6 +321,7 @@ struct bus_type tb_bus_type = {
    > .probe = tb_service_probe,
    > .remove = tb_service_remove,
    > .shutdown = tb_service_shutdown,
    > + .has_probe_authorization = true,
    > };
    >
    > static void tb_domain_release(struct device *dev)
    > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
    > index fb476665f52d..f57b5a7a90ca 100644
    > --- a/drivers/usb/core/driver.c
    > +++ b/drivers/usb/core/driver.c
    > @@ -2028,4 +2028,5 @@ struct bus_type usb_bus_type = {
    > .match = usb_device_match,
    > .uevent = usb_uevent,
    > .need_parent_lock = true,
    > + .has_probe_authorization = true,
    > };
    > diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h
    > index 062777a45a74..571a2f6e7c1d 100644
    > --- a/include/linux/device/bus.h
    > +++ b/include/linux/device/bus.h
    > @@ -69,6 +69,9 @@ struct fwnode_handle;
    > * @lock_key: Lock class key for use by the lock validator
    > * @need_parent_lock: When probing or removing a device on this bus, the
    > * device core should lock the device's parent.
    > + * @has_probe_authorization: Set true to indicate to the driver-core to skip
    > + * the authorization checks and let bus drivers
    > + * handle it locally.
    > *
    > * A bus is a channel between the processor and one or more devices. For the
    > * purposes of the device model, all devices are connected via a bus, even if
    > @@ -112,6 +115,7 @@ struct bus_type {
    > struct lock_class_key lock_key;
    >
    > bool need_parent_lock;
    > + bool has_probe_authorization;
    > };
    >
    > extern int __must_check bus_register(struct bus_type *bus);
    > --
    > 2.25.1

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