Linux Virtualization - Sep 2021 - [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 at rowland.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
at mail.gmail.com/
> >
> > Reviewed-by: Dan Williams <dan.j.williams at intel.com>
> > Signed-off-by: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy at linux.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.

On Wed, Sep 29, 2021 at 06:55:12PM -0700, Dan Williams
wrote:
> On Wed, Sep 29, 2021 at 6:43 PM Alan Stern <stern at
rowland.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
at mail.gmail.com/
> > >
> > > Reviewed-by: Dan Williams <dan.j.williams at intel.com>
> > > Signed-off-by: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy at linux.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.
How about implementing "library" versions of show_authorized() and 
store_authorized() that the bus-specific attribute routines can call?  
These library routines would handle parsing the input values, storing 
the new flag, and displaying the stored flag value.  That way at 
least the common parts of these APIs would be centralized in the 
driver core, and any additional functionality could easily be added 
by the bus-specific attribute routine.

Alan Stern