Messages in this thread | | | Subject | Re: [PATCH v4 3/5] lib/test: Introduce cpumask KUnit test suite | From | Sander Vanheule <> | Date | Wed, 20 Jul 2022 14:43:49 +0200 |
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Hi David, Maíra,
On Wed, 2022-07-20 at 13:24 +0800, David Gow wrote: > On Wed, Jul 20, 2022 at 5:31 AM Maíra Canal <mairacanal@riseup.net> wrote: > > > > > Add a basic suite of tests for cpumask, providing some tests for empty > > > and completely filled cpumasks. > > > > > > Signed-off-by: Sander Vanheule <sander@svanheule.net> > > > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > > > The tests test_cpumask_weight and test_cpumask_last are failing on all > > architectures, as can be seen on [1]. Also this test doesn't follow the > > standard style for KUnit tests [2]. > > > > [1] > > https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20220718/testrun/10865066/suite/kunit/tests/ > > [2] https://docs.kernel.org/dev-tools/kunit/style.html > > > > CC: Brendan Higgins <brendanhiggins@google.com> > > CC: David Gow <davidgow@google.com> > > > > Best Regards, > > - Maíra Canal > > > > Hmm... this test passes on the default kunit_tool configs for UML and > x86_64, which are all without SMP. > > It looks like the flaw is that, if CONFIG_NR_CPUS is greater than the > actual number of CPUs present, then the cpu_possible_mask (correctly) > won't be full. > > I'm not sure what the right fix is: but removing the checks for > cpu_possible_mask being full is probably the way to go. Unless we want > to plumb through some actual detail about the underlying system and > check against that, it doesn't make sense. (Or, we could generate an > artificial "possilbe_mask" which is always full, and test the cpu > against that. But we sort-of already do that with mask_all anyway.)
The description of cpu_possible_mask does indeed allow for it to not be filled completely.
> > So, my recommendation for a fix would be: > - Get rid of "KUNIT_EXPECT_TRUE(test, cpumask_full(cpu_possible_mask));"
As per the above, I'll remove this (faulty) check.
> - Replace "KUNIT_EXPECT_EQ(test, nr_cpumask_bits - 1, > cpumask_last(cpu_possible_mask));" with a KUNIT_EXPECT_GE()
I think we can actually use KUNIT_EXPECT_EQ(test, nr_cpu_ids - 1, ...) here.
Since cpumask_first() on the same mask must return at most nr_cpu_ids - 1 for a valid result, cpumask_last() cannot return anything larger than this value. This implies that cpu_possible_mask cannot contain gaps if its weight equals nr_cpu_ids (which is checked in test_cpumask_weight).
> - _Maybe_ add some debug logging with the cpumask value being checked, > as it's a pain to tell from the expectation failure messages. e.g., > kunit_info(test, "cpu_possible_mask = '%*pb[l]'\n", > cpumask_pr_args(cpu_possible_mask));
That would be a useful addition, I'll see where I can add it.
Best, Sander >
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