Re: [PATCH v4 3/3] configfs: Add unit tests

From: Bart Van Assche
Date: Tue Aug 10 2021 - 14:45:50 EST


On 8/10/21 9:50 AM, Christoph Hellwig wrote:
On Mon, Aug 09, 2021 at 11:31:23AM -0700, Bart Van Assche wrote:
+config CONFIGFS_KUNIT_TEST
+ bool "Configfs Kunit test" if !KUNIT_ALL_TESTS
+ depends on CONFIGFS_FS && KUNIT=y
+ default KUNIT_ALL_TESTS

Why does it depend on KUNIT=y? What is the issue with a modular KUNIT
build?

The unit tests calls do_mount(). do_mount() has not been exported and
hence is not available to kernel modules. Hence the exclusion of KUNIT=m.

You should probably document that. But then again this is another
big red flag that this code should live in userspace.

To me this sounds like userspace would be a better place for these
kinds of tests.

Splitting the code that can only be run from inside the kernel (creation
of configfs attributes) and the code that can be run from user space and
making sure that the two run in a coordinated fashion would involve a
significant amount of work. I prefer to keep the current approach.

But userspace is the right place to do this kind of pathname
based file system I/O.

Shuah, as selftest maintainer, can you recommend an approach? How about splitting patch 3/3 from this series into a kernel module (the code that creates the configfs test attributes) and user space code (the code that reads and writes the configfs attributes) and adding the user space code in a subdirectory of tools/testing/selftests/?

Thanks,

Bart.