On Sat, Nov 19, 2022 at 12:13 AM David Gow <davidgow@xxxxxxxxxx> wrote: > > KUnit does a few expensive things when enabled. This hasn't been a > problem because KUnit was only enabled on test kernels, but with a few > people enabling (but not _using_) KUnit on production systems, we need a > runtime way of handling this. > > Provide a 'kunit_running' static key (defaulting to false), which allows > us to hide any KUnit code behind a static branch. This should reduce the > performance impact (on other code) of having KUnit enabled to a single > NOP when no tests are running. > > Note that, while it looks unintuitive, tests always run entirely within > __kunit_test_suites_init(), so it's safe to decrement the static key at > the end of this function, rather than in __kunit_test_suites_exit(), > which is only there to clean up results in debugfs. > > Signed-off-by: David Gow <davidgow@xxxxxxxxxx> Reviewed-by: Daniel Latypov <dlatypov@xxxxxxxxxx> I didn't know anything about the static key support in the kernel before this patch. But from what I read and saw of other uses, this looks good to me. One small question/nit about how we declare the key below. <snip> > +/* Static key: true if any KUnit tests are currently running */ > +extern struct static_key_false kunit_running; Is there any documented preference between this and DECLARE_STATIC_KEY_FALSE(kunit_running); ? I see 89 instances of this macro and 45 of `extern struct static_key_false`. So I'd vote for the macro since it seems like the newer approach and more common. Daniel
