linux-kernel - Re: [PATCH v2 1/6] driver core: Move the "authorized" attribute from USB/Thunderbolt to core

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Date:   Wed, 29 Sep 2021 18:55:12 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Alan Stern <stern@...land.harvard.edu>
Cc:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Borislav Petkov <bp@...en8.de>, X86 ML <x86@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Andreas Noever <andreas.noever@...il.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Jason Wang <jasowang@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        USB list <linux-usb@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v2 1/6] driver core: Move the "authorized" attribute from
 USB/Thunderbolt to core

On Wed, Sep 29, 2021 at 6:43 PM Alan Stern <stern@...land.harvard.edu> wrote:
>
> On Wed, Sep 29, 2021 at 06:05:06PM -0700, Kuppuswamy Sathyanarayanan wrote:
> > Currently bus drivers like "USB" or "Thunderbolt" implement a custom
> > version of device authorization to selectively authorize the driver
> > probes. Since there is a common requirement, move the "authorized"
> > attribute support to the driver core in order to allow it to be used
> > by other subsystems / buses.
> >
> > Similar requirements have been discussed in the PCI [1] community for
> > PCI bus drivers as well.
> >
> > No functional changes are intended. It just converts authorized
> > attribute from int to bool and moves it to the driver core. There
> > should be no user-visible change in the location or semantics of
> > attributes for USB devices.
> >
> > Regarding thunderbolt driver, although it declares sw->authorized as
> > "int" and allows 0,1,2 as valid values for sw->authorized attribute,
> > but within the driver, in all authorized attribute related checks,
> > it is treated as bool value. So when converting the authorized
> > attribute from int to bool value, there should be no functional
> > changes other than value 2 being not visible to the user.
> >
> > [1]: https://lore.kernel.org/all/CACK8Z6E8pjVeC934oFgr=VB3pULx_GyT2NkzAogdRQJ9TKSX9A@mail.gmail.com/
> >
> > Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>
> Since you're moving the authorized flag from the USB core to the
> driver core, the corresponding sysfs attribute functions should be
> moved as well.

Unlike when 'removable' moved from USB to the driver core there isn't
a common definition for how the 'authorized' sysfs-attribute behaves
across buses. The only common piece is where this flag is stored in
the data structure, i.e. the 'authorized' sysfs interface is
purposefully left bus specific.

> Also, you ignored the usb_[de]authorize_interface() functions and
> their friends.

Ugh, yes.