[PATCH v1 0/4] driver core, iio: suppress driver_override

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

Recently Sashiko started reporting the missed NULL check of
spi_get_device_match_data() or device_get_match_data() in SPI drivers
in IIO subsystem. It appears that the way to crash can be made by use
of driver_override sysfs attribute. However, many drivers, that may be
instantiate via ACPI, OF, or, in some cases, user space won't work
without necessary driver data. These are, e.g., most of the drivers
in IIO subsystem. Trying to override the driver for the device that
has no matching entry makes no sense in such cases and might lead to
a crash, when the driver is not prepared for that.  Instead of adding
a NULL check for driver data pointer in each of that drivers, effectively
meaning a dead code for normal functionality, introduce a special
attribute in the struct device_driver to allow drivers just to hide
the attribute for good.

The last two patches are the examples of use and code simplification
at the same time.

I consider getting an Ack from Mark for SPI, and from Jonathan for IIO
and route this via driver core, while providing an immutable branch/tag
for the above mentioned stakeholders.

Note, this doesn't change the state of affairs for some busses that
do not have driver_override flag set while using custom approach.
On a brief look it's the s390 crypto case which may not ever need
the above and hence left untouched.

Andy Shevchenko (4):
  driver core: allow certain drivers prohibit override via sysfs
  spi: Support suppress_override_attrs flag
  iio: imu: inv_mpu6050: Suppress driver_override sysfs attribute
  iio: imu: inv_icm42600: Suppress driver_override sysfs attribute

 Documentation/driver-api/driver-model/binding.rst |  4 ++++
 drivers/base/bus.c                                |  4 ++--
 drivers/iio/imu/inv_icm42600/inv_icm42600_spi.c   |  8 ++------
 drivers/iio/imu/inv_mpu6050/inv_mpu_spi.c         |  3 +--
 drivers/spi/spi.c                                 | 11 +++++++++++
 include/linux/device/driver.h                     |  2 ++
 6 files changed, 22 insertions(+), 10 deletions(-)

-- 
2.50.1