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SubjectRe: [PATCH v2 linux-kselftest-test 1/3] kunit: allow kunit tests to be loaded as a module
On Tue, 8 Oct 2019, Brendan Higgins wrote:

> On Tue, Oct 08, 2019 at 03:55:44PM +0100, Alan Maguire wrote:
> > as tests are added to kunit, it will become less feasible to execute
> > all built tests together. By supporting modular tests we provide
> > a simple way to do selective execution on a running system; specifying
> >
> > CONFIG_KUNIT=y
> > CONFIG_KUNIT_EXAMPLE_TEST=m
> >
> > ...means we can simply "insmod example-test.ko" to run the tests.
> >
> > To achieve this we need to
> >
> > o export the required symbols in kunit
> > o support a new way of declaring test suites. Because a module cannot
> > do multiple late_initcall()s, we provide a kunit_test_suites() macro
> > to declare multiple suites within the same module at once.
> >
> > Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> > Signed-off-by: Knut Omang <knut.omang@oracle.com>
> >
> > ---
> > include/kunit/test.h | 30 +++++++++++++++++++++++-------
> > kernel/sysctl-test.c | 6 +++++-
> > lib/Kconfig.debug | 4 ++--
> > lib/kunit/Kconfig | 4 ++--
> > lib/kunit/assert.c | 8 ++++++++
> > lib/kunit/example-test.c | 6 +++++-
> > lib/kunit/string-stream-test.c | 9 +++++++--
> > lib/kunit/string-stream.c | 7 +++++++
> > lib/kunit/test-test.c | 8 ++++++--
> > lib/kunit/test.c | 8 ++++++++
> > lib/kunit/try-catch.c | 8 ++++++--
> > 11 files changed, 79 insertions(+), 19 deletions(-)
> >
> > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > index dba4830..9fc6c1b 100644
> > --- a/include/kunit/test.h
> > +++ b/include/kunit/test.h
> > @@ -12,6 +12,7 @@
> > #include <kunit/assert.h>
> > #include <kunit/try-catch.h>
> > #include <linux/kernel.h>
> > +#include <linux/module.h>
> > #include <linux/slab.h>
> > #include <linux/types.h>
> >
> > @@ -204,24 +205,39 @@ struct kunit {
> > * Registers @suite with the test framework. See &struct kunit_suite for
> > * more information.
> > *
> > - * NOTE: Currently KUnit tests are all run as late_initcalls; this means
> > + * When builtin, KUnit tests are all run as late_initcalls; this means
> > * that they cannot test anything where tests must run at a different init
> > * phase. One significant restriction resulting from this is that KUnit
> > * cannot reliably test anything that is initialize in the late_init phase;
> > * another is that KUnit is useless to test things that need to be run in
> > * an earlier init phase.
> > *
> > + * An alternative is to build the tests as a module. Because modules
> > + * do not support multiple late_initcall()s, we need to initialize an
> > + * array of suites for a module.
> > + *
> > * TODO(brendanhiggins@google.com): Don't run all KUnit tests as
> > * late_initcalls. I have some future work planned to dispatch all KUnit
> > * tests from the same place, and at the very least to do so after
> > * everything else is definitely initialized.
> > */
> > -#define kunit_test_suite(suite) \
> > - static int kunit_suite_init##suite(void) \
> > - { \
> > - return kunit_run_tests(&suite); \
> > - } \
> > - late_initcall(kunit_suite_init##suite)
> > +#define kunit_test_suites(...) \
> > + static struct kunit_suite *suites[] = { __VA_ARGS__, NULL}; \
> > + static int kunit_test_suites_init(void) \
> > + { \
> > + unsigned int i; \
> > + for (i = 0; suites[i] != NULL; i++) \
> > + kunit_run_tests(suites[i]); \
> > + return 0; \
> > + } \
> > + late_initcall(kunit_test_suites_init); \
> > + static void __exit kunit_test_suites_exit(void) \
> > + { \
> > + return; \
> > + } \
> > + module_exit(kunit_test_suites_exit)
> > +
> > +#define kunit_test_suite(suite) kunit_test_suites(suite)
>
> I think it is fine to just rename this kunit_test_suites.
>

Will do.

> > /*
> > * Like kunit_alloc_resource() below, but returns the struct kunit_resource
> > diff --git a/kernel/sysctl-test.c b/kernel/sysctl-test.c
> > index 2a63241..15161c5 100644
> > --- a/kernel/sysctl-test.c
> > +++ b/kernel/sysctl-test.c
> > @@ -389,4 +389,8 @@ static void sysctl_test_api_dointvec_write_single_greater_int_max(
> > .test_cases = sysctl_test_cases,
> > };
> >
> > -kunit_test_suite(sysctl_test_suite);
> > +kunit_test_suite(&sysctl_test_suite);
> > +
> > +#ifdef MODULE
> > +MODULE_LICENSE("GPL");
> > +#endif /* MODULE */
>
> Here and elsewhere: the "ifdef/endif MODULE" should not be necessary.
>

Will fix, thanks!

> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index a3017a5..f9f411a6 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -1951,10 +1951,10 @@ config TEST_SYSCTL
> > If unsure, say N.
> >
> > config SYSCTL_KUNIT_TEST
> > - bool "KUnit test for sysctl"
> > + tristate "KUnit test for sysctl"
> > depends on KUNIT
> > help
> > - This builds the proc sysctl unit test, which runs on boot.
> > + This builds the proc sysctl unit test, which runs on boot/module load.
> > Tests the API contract and implementation correctness of sysctl.
> > For more information on KUnit and unit tests in general please refer
> > to the KUnit documentation in Documentation/dev-tools/kunit/.
> [...]
> > diff --git a/lib/kunit/example-test.c b/lib/kunit/example-test.c
> > index f64a829..6c6a408 100644
> > --- a/lib/kunit/example-test.c
> > +++ b/lib/kunit/example-test.c
> > @@ -85,4 +85,8 @@ static int example_test_init(struct kunit *test)
> > * This registers the above test suite telling KUnit that this is a suite of
> > * tests that need to be run.
> > */
> > -kunit_test_suite(example_test_suite);
> > +kunit_test_suite(&example_test_suite);
> > +
> > +#ifdef MODULE
> > +MODULE_LICENSE("GPL");
> > +#endif /* MODULE */
>
> nit: The "ifdef/endif MODULE" should not be necessary.
>
> > diff --git a/lib/kunit/string-stream-test.c b/lib/kunit/string-stream-test.c
> > index 76cc05e..7a3e7a0 100644
> > --- a/lib/kunit/string-stream-test.c
> > +++ b/lib/kunit/string-stream-test.c
> > @@ -45,8 +45,13 @@ static void string_stream_test_get_string(struct kunit *test)
> > {}
> > };
> >
> > -static struct kunit_suite string_stream_test_suite = {
> > +struct kunit_suite string_stream_test_suite = {
> > .name = "string-stream-test",
> > .test_cases = string_stream_test_cases
> > };
> > -kunit_test_suite(string_stream_test_suite);
> > +
> > +kunit_test_suite(&string_stream_test_suite);
> > +
> > +#ifdef MODULE
> > +MODULE_LICENSE("GPL");
> > +#endif /* MODULE */
> > diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c
> > index e6d17aa..e4f3a97 100644
> > --- a/lib/kunit/string-stream.c
> > +++ b/lib/kunit/string-stream.c
> > @@ -100,6 +100,7 @@ int string_stream_vadd(struct string_stream *stream,
> >
> > return 0;
> > }
> > +EXPORT_SYMBOL_GPL(string_stream_vadd);
>
> Is this actually needed by anything other than lib/kunit/test.c right
> now? Maybe we should move the include file into the kunit/ directory to
> hide these so no one else can use them.
>

I tried this, and it's the right answer I think but it exposes
a problem with symbol visibility when kunit is compiled as a module.
More on this below...

> > int string_stream_add(struct string_stream *stream, const char *fmt, ...)
> > {
> > @@ -112,6 +113,7 @@ int string_stream_add(struct string_stream *stream, const char *fmt, ...)
> >
> > return result;
> > }
> > +EXPORT_SYMBOL_GPL(string_stream_add);
> [...]
> > diff --git a/lib/kunit/test.c b/lib/kunit/test.c
> > index c83c0fa..e7896f1 100644
> > --- a/lib/kunit/test.c
> > +++ b/lib/kunit/test.c
> [...]
> > @@ -50,6 +51,7 @@ static unsigned long kunit_test_timeout(void)
> > * For more background on this topic, see:
> > * https://mike-bland.com/2011/11/01/small-medium-large.html
> > */
> > +#ifndef MODULE
>
> Why is this block of code "ifndef MODULE"?
>

Symbol visibility is the problem again; sysctl_hung_task_timeout_secs
isn't exported so when kunit is a module it can't find the symbol.

I think I saw Kees mentioned something about symbol lookup too; in KTF
Knut solved this by defining ktf_find_symbol(). I'd suggest we may need a
kunit_find_symbol() with a function signature

void *kunit_find_symbol(const char *modname, const char *symbol_name);

...which does a [module_]kallsyms_lookup_sym().

If the above makes sense I can look at adding it as a patch (and adding
a test of it of course!). What do you think?

> > if (sysctl_hung_task_timeout_secs) {
> > /*
> > * If sysctl_hung_task is active, just set the timeout to some
> > @@ -60,9 +62,9 @@ static unsigned long kunit_test_timeout(void)
> > */
> > timeout_msecs = (sysctl_hung_task_timeout_secs - 1) *
> > MSEC_PER_SEC;
> > - } else {
> > + } else
> > +#endif
> > timeout_msecs = 300 * MSEC_PER_SEC; /* 5 min */
> > - }
> >
> > return timeout_msecs;
> > }
> > @@ -106,6 +108,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
> >
> > try_catch->catch(try_catch->context);
> > }
> > +EXPORT_SYMBOL_GPL(kunit_try_catch_run);
> >
> > void kunit_try_catch_init(struct kunit_try_catch *try_catch,
> > struct kunit *test,
> > @@ -116,3 +119,4 @@ void kunit_try_catch_init(struct kunit_try_catch *try_catch,
> > try_catch->try = try;
> > try_catch->catch = catch;
> > }
> > +EXPORT_SYMBOL_GPL(kunit_try_catch_init);
>
> This code should also probably be hidden from outside of kunit/.
>

Sure, will do.

Thanks again for the review!

Alan

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