Re: [PATCH v7 0/8] gpio: implement the configfs testing module

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Fri, Oct 8, 2021 at 10:17 AM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
>
> I'm respinning this series now because I noticed that I need to start writing
> tests for my work on the new libgpiod v2 code to make sense (it's just becoming
> too complicated to make even remotely functional without test coverage). At the
> same time I don't want to rewrite the tests using gpio-mockup if the goal is to
> replace it with gpio-sim anyway.
>
> I fixed issues pointed out by Al Viro and made sure that references are
> correctly counted (including error paths) and that memory allocated for the
> pending and live groups gets freed.
>
> ===
>
> Cc'ing Viresh too.
>
> Viresh: while there's still a long way to go before the libgpio v2.0 release,
> in order to merge the Rust bindings, we'll need a test-suite similar to what
> we have now for C++ and Python bindings, except that it will have to be based
> on the gpio-sim module when it makes its way into mainline.
>
> ===
>
> This series adds a new GPIO testing module based on configfs committable items
> and sysfs. The goal is to provide a testing driver that will be configurable
> at runtime (won't need module reload) and easily extensible. The control over
> the attributes is also much more fine-grained than in gpio-mockup.
>
> This series also contains a respin of the patches I sent separately to the
> configfs maintainers - these patches implement the concept of committable
> items that was well defined for a long time but never actually completed.
>
> Apart from the new driver itself, its selftests and the configfs patches, this
> series contains some changes to the bitmap API - most importantly: it adds
> devres managed variants of bitmap_alloc() and bitmap_zalloc().
>
> v1 -> v2:
> - add selftests for gpio-sim
> - add helper programs for selftests
> - update the configfs rename callback to work with the new API introduced in
>   v5.11
> - fix a missing quote in the documentation
> - use !! whenever using bits operation that are required to return 0 or 1
> - use provided bitmap API instead of reimplementing copy or fill operations
> - fix a deadlock in gpio_sim_direction_output()
> - add new read-only configfs attributes for mapping of configfs items to GPIO
>   device names
> - and address other minor issues pointed out in reviews of v1
>
> v2 -> v3:
> - use devm_bitmap_alloc() instead of the zalloc variant if we're initializing
>   the bitmap with 1s
> - drop the patch exporting device_is_bound()
> - don't return -ENODEV from dev_nam and chip_name configfs attributes, return
>   a string indicating that the device is not available yet ('n/a')
> - fix indentation where it makes sense
> - don't protect IDA functions which use their own locking and where it's not
>   needed
> - use kmemdup() instead of kzalloc() + memcpy()
> - collected review tags
> - minor coding style fixes
>
> v3 -> v4:
> - return 'none' instead of 'n/a' from dev_name and chip_name before the device
>   is registered
> - use sysfs_emit() instead of s*printf()
> - drop GPIO_SIM_MAX_PROP as it's only used in an array's definition where it's
>   fine to hardcode the value
>
> v4 -> v5:
> - drop lib patches that are already upstream
> - use BIT() instead of (1UL << bit) for flags
> - fix refcounting for the configfs_dirent in rename()
> - drop d_move() from the rename() callback
> - free memory allocated for the live and pending groups in configfs_d_iput()
>   and not in detach_groups()
> - make sure that if a group of some name is in the live directory, a new group
>   with the same name cannot be created in the pending directory
>
> v5 -> v6:
> - go back to using (1UL << bit) instead of BIT()
> - if the live group dentry doesn't exist for whatever reason at the time when
>   mkdir() in the pending group is called (would be a BUG()), return -ENOENT
>   instead of -EEXIST which should only be returned if given subsystem already
>   exists in either live or pending group
>
> v6 -> v7:
> - as detailed by Andy in commit 6fda593f3082 ("gpio: mockup: Convert to use
>   software nodes") removing device properties after the platform device is
>   removed but before the GPIO device gets dropped can lead to a use-after-free
>   bug - use software nodes to manually control the freeing of the properties
>
> Bartosz Golaszewski (8):
>   configfs: increase the item name length
>   configfs: use (1UL << bit) for internal flags
>   configfs: implement committable items
>   samples: configfs: add a committable group
>   gpio: sim: new testing module
>   selftests: gpio: provide a helper for reading chip info
>   selftests: gpio: add a helper for reading GPIO line names
>   selftests: gpio: add test cases for gpio-sim
>
>  Documentation/admin-guide/gpio/gpio-sim.rst   |  72 ++
>  Documentation/filesystems/configfs.rst        |   6 +-
>  drivers/gpio/Kconfig                          |   8 +
>  drivers/gpio/Makefile                         |   1 +
>  drivers/gpio/gpio-sim.c                       | 886 ++++++++++++++++++
>  fs/configfs/configfs_internal.h               |  22 +-
>  fs/configfs/dir.c                             | 276 +++++-
>  include/linux/configfs.h                      |   3 +-
>  samples/configfs/configfs_sample.c            | 153 +++
>  tools/testing/selftests/gpio/.gitignore       |   2 +
>  tools/testing/selftests/gpio/Makefile         |   4 +-
>  tools/testing/selftests/gpio/config           |   1 +
>  tools/testing/selftests/gpio/gpio-chip-info.c |  57 ++
>  tools/testing/selftests/gpio/gpio-line-name.c |  55 ++
>  tools/testing/selftests/gpio/gpio-sim.sh      | 229 +++++
>  15 files changed, 1752 insertions(+), 23 deletions(-)
>  create mode 100644 Documentation/admin-guide/gpio/gpio-sim.rst
>  create mode 100644 drivers/gpio/gpio-sim.c
>  create mode 100644 tools/testing/selftests/gpio/gpio-chip-info.c
>  create mode 100644 tools/testing/selftests/gpio/gpio-line-name.c
>  create mode 100755 tools/testing/selftests/gpio/gpio-sim.sh
>
> --
> 2.30.1
>

Another ping...

Bart