On Tue, Nov 22, 2022 at 9:31 AM Daniel Latypov <dlatypov@xxxxxxxxxx> wrote: > > 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. > Yeah, there was no particular reason I put 'extern struct static_key_false'. I'll change it to DECLARE_STATIC_KEY_FALSE in v3. Cheers, -- David
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