On Thu, Jun 04, 2020 at 02:51:03PM +0530, Sumit Garg wrote:
> On Thu, 4 Jun 2020 at 14:07, Jarkko Sakkinen
> <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> >
> > On Mon, Jun 01, 2020 at 06:06:43PM +0300, Maxim Uvarov wrote:
> > > With the evolving use-cases for TEE bus, now it's required to support
> > > multi-stage enumeration process. But using a simple index doesn't
> > > suffice this requirement and instead leads to duplicate sysfs entries.
> > > So instead switch to use more informative device UUID for sysfs entry
> > > like:
> > > /sys/bus/tee/devices/optee-ta-<uuid>
> > >
> > > Signed-off-by: Maxim Uvarov <maxim.uvarov@xxxxxxxxxx>
> > > Reviewed-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
> >
> > Why do you mean by duplicate sysfs entries?
> >
>
> It's just about the device being added with the same name as of the
> device which is already present on the TEE bus. So this leads to
> duplicate sysfs entry error for device node which is created during
> device_register() execution flow.
>
> > > ---
> > > Documentation/ABI/testing/sysfs-bus-optee-devices | 8 ++++++++
> > > MAINTAINERS | 1 +
> > > drivers/tee/optee/device.c | 6 +++---
> > > 3 files changed, 12 insertions(+), 3 deletions(-)
> > > create mode 100644 Documentation/ABI/testing/sysfs-bus-optee-devices
> > >
> > > diff --git a/Documentation/ABI/testing/sysfs-bus-optee-devices b/Documentation/ABI/testing/sysfs-bus-optee-devices
> > > new file mode 100644
> > > index 000000000000..0ae04ae5374a
> > > --- /dev/null
> > > +++ b/Documentation/ABI/testing/sysfs-bus-optee-devices
> > > @@ -0,0 +1,8 @@
> > > +What: /sys/bus/tee/devices/optee-ta-<uuid>/
> > > +Date: May 2020
> > > +KernelVersion 5.7
> > > +Contact: tee-dev@xxxxxxxxxxxxxxxx
> > > +Description:
> > > + OP-TEE bus provides reference to registered drivers under this directory. The <uuid>
> > > + matches Trusted Application (TA) driver and corresponding TA in secure OS. Drivers
> > > + are free to create needed API under optee-ta-<uuid> directory.
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index ecc0749810b0..6717afef2de3 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -12516,6 +12516,7 @@ OP-TEE DRIVER
> > > M: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> > > L: tee-dev@xxxxxxxxxxxxxxxx
> > > S: Maintained
> > > +F: Documentation/ABI/testing/sysfs-bus-optee-devices
> > > F: drivers/tee/optee/
> > >
> > > OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER
> > > diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c
> > > index e3a148521ec1..ed3d1ddfa52b 100644
> > > --- a/drivers/tee/optee/device.c
> > > +++ b/drivers/tee/optee/device.c
> > > @@ -65,7 +65,7 @@ static int get_devices(struct tee_context *ctx, u32 session,
> > > return 0;
> > > }
> > >
> > > -static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
> > > +static int optee_register_device(const uuid_t *device_uuid)
> > > {
> > > struct tee_client_device *optee_device = NULL;
> > > int rc;
> > > @@ -75,7 +75,7 @@ static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
> > > return -ENOMEM;
> > >
> > > optee_device->dev.bus = &tee_bus_type;
> > > - dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);
> > > + dev_set_name(&optee_device->dev, "optee-ta-%pUl", device_uuid);
> >
> > This code is and already was broken. If dev_set_name() returns -ENOMEM,
> > the name will be a null pointer.
>
> Is this an expected error scenario? dev_set_name() is invoked at
> numerous places in the kernel without any error check.
>
> >
> > Also, I don't get how you can just swap the name without potentially
> > breaking the backwards compatiblity towards the user space.
>
> As of now, there isn't any compatibility concerns with user space as
> these TEE devices are meant to be used by kernel drivers only. TEE
> user-space interface is quite separate (see: Documentation/tee.txt).
OK, probably would make sense to have this in the commit message as a
remark.
/Jarkko
