Re: [PATCH v5 2/3] printf: break kunit into test cases

Tamir Duberstein
2025-03-06T17:29:25Z

On Thu, Mar 6, 2025 at 11:44 AM Petr Mladek <pmladek@suse.com> wrote:
>
> On Fri 2025-02-21 15:34:31, Tamir Duberstein wrote:
> > Move all tests into `printf_test_cases`. This gives us nicer output in
> > the event of a failure.
> >
> > Combine `plain_format` and `plain_hash` into `hash_pointer` since
> > they're testing the same scenario.
> >
> > Signed-off-by: Tamir Duberstein <tamird@gmail.com>
> > ---
> > lib/tests/printf_kunit.c | 331 +++++++++++++++++------------------------------
> > 1 file changed, 121 insertions(+), 210 deletions(-)
> >
> > diff --git a/lib/tests/printf_kunit.c b/lib/tests/printf_kunit.c
> > index 287bbfb61148..013df6f6dd49 100644
> > --- a/lib/tests/printf_kunit.c
> > +++ b/lib/tests/printf_kunit.c
> > @@ -38,13 +38,8 @@ static unsigned int total_tests;
> > static char *test_buffer;
> > static char *alloced_buffer;
> >
> > -static struct kunit *kunittest;
> > -
> > -#define tc_fail(fmt, ...) \
> > - KUNIT_FAIL(kunittest, fmt, ##__VA_ARGS__)
> > -
> > -static void __printf(4, 0)
> > -do_test(int bufsize, const char *expect, int elen,
> > +static void __printf(5, 0)
> > +do_test(struct kunit *kunittest, int bufsize, const char *expect, int elen,
> > const char *fmt, va_list ap)
> > {
> > va_list aq;
> > @@ -58,59 +53,64 @@ do_test(int bufsize, const char *expect, int elen,
> [...]
> >
> > if (memcmp(test_buffer, expect, written)) {
> > - tc_fail("vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'",
> > - bufsize, fmt, test_buffer, written, expect);
> > + KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'",
> > + bufsize, fmt, test_buffer, written, expect);
> > return;
> > }
> > }
> >
> > -static void __printf(3, 4)
> > -__test(const char *expect, int elen, const char *fmt, ...)
> > +static void __printf(4, 0)
>
> This should be:
>
> static void __printf(4, 5)
>
> The 2nd parameter is zero when the variable list of parameters is
> passed using va_list.

Yeah, thanks for the catch. I fixed this locally after you observed
the same on the scanf-kunit series.

> > +__test(struct kunit *kunittest, const char *expect, int elen, const char *fmt, ...)
> > {
> > va_list ap;
> > int rand;
> > char *p;
>
> > @@ -247,89 +225,44 @@ plain_format(void)
> > #define ZEROS ""
> > #define ONES ""
> >
> > -static int
> > -plain_format(void)
> > -{
> > - /* Format is implicitly tested for 32 bit machines by plain_hash() */
> > - return 0;
> > -}
> > -
> > #endif /* BITS_PER_LONG == 64 */
> >
> > -static int
> > -plain_hash_to_buffer(const void *p, char *buf, size_t len)
> > +static void
> > +plain_hash_to_buffer(struct kunit *kunittest, const void *p, char *buf, size_t len)
> > {
> > - int nchars;
> > -
> > - nchars = snprintf(buf, len, "%p", p);
> > -
> > - if (nchars != PTR_WIDTH)
> > - return -1;
> > + KUNIT_ASSERT_EQ(kunittest, snprintf(buf, len, "%p", p), PTR_WIDTH);
> >
> > if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
> > kunit_warn(kunittest, "crng possibly not yet initialized. plain 'p' buffer contains \"%s\"",
> > PTR_VAL_NO_CRNG);
> > - return 0;
> > }
> > -
> > - return 0;
> > }
> >
> > -static int
> > -plain_hash(void)
> > -{
> > - char buf[PLAIN_BUF_SIZE];
> > - int ret;
> > -
> > - ret = plain_hash_to_buffer(PTR, buf, PLAIN_BUF_SIZE);
> > - if (ret)
> > - return ret;
> > -
> > - if (strncmp(buf, PTR_STR, PTR_WIDTH) == 0)
> > - return -1;
> > -
> > - return 0;
> > -}
> > -
> > -/*
> > - * We can't use test() to test %p because we don't know what output to expect
> > - * after an address is hashed.
> > - */
> > static void
> > -plain(void)
> > +hash_pointer(struct kunit *kunittest)
> > {
> > - int err;
> > + if (no_hash_pointers)
> > + kunit_skip(kunittest, "hash pointers disabled");
> >
> > - if (no_hash_pointers) {
> > - kunit_warn(kunittest, "skipping plain 'p' tests");
> > - return;
> > - }
> > + char buf[PLAIN_BUF_SIZE];
> >
> > - err = plain_hash();
> > - if (err) {
> > - tc_fail("plain 'p' does not appear to be hashed");
> > - return;
> > - }
> > + plain_hash_to_buffer(kunittest, PTR, buf, PLAIN_BUF_SIZE);
> >
> > - err = plain_format();
> > - if (err) {
> > - tc_fail("hashing plain 'p' has unexpected format");
> > - }
> > + /*
> > + * We can't use test() to test %p because we don't know what output to expect
> > + * after an address is hashed.
> > + */
>
> The code does not longer print a reasonable error message on failure.
> I would extend the comment to make it easier to understand the
> meaning. Also I would use the imperative style. Something like:
>
> /*
> * The hash of %p is unpredictable, therefore test() cannot be used.
> * Instead, verify that the first 32 bits are zeros on a 64-bit system,
> * and confirm the non-hashed value is not printed.
> */

I'll make this change. Note that this comment isn't changing here, it
only appears to be because its indentation changed.

> > +
> > + KUNIT_EXPECT_MEMEQ(kunittest, buf, ZEROS, strlen(ZEROS));
> > + KUNIT_EXPECT_MEMNEQ(kunittest, buf+strlen(ZEROS), PTR_STR, PTR_WIDTH);
>
> This looks wrong. It should be either:
>
> KUNIT_EXPECT_MEMNEQ(kunittest, buf, PTR_STR, PTR_WIDTH);
>
> or
>
> KUNIT_EXPECT_MEMNEQ(kunittest,
> buf + strlen(ZEROS),
> PTR_STR + strlen(ZEROS),
> PTR_WIDTH - strlen(ZEROS));
>
> I would use the 1st variant. It is easier and it works the same way
> as the original check.

Ah, I see. Done as you ask.

>
> Anyway, it is a great clean up of the pointer tests. I have wanted to do it
> since a long time but I never found time.

Thanks!

> > }
> >
> > static void
> > -test_hashed(const char *fmt, const void *p)
> > +test_hashed(struct kunit *kunittest, const char *fmt, const void *p)
> > {
> > char buf[PLAIN_BUF_SIZE];
> > - int ret;
> >
> > - /*
> > - * No need to increase failed test counter since this is assumed
> > - * to be called after plain().
> > - */
> > - ret = plain_hash_to_buffer(p, buf, PLAIN_BUF_SIZE);
> > - if (ret)
> > - return;
> > + plain_hash_to_buffer(kunittest, p, buf, PLAIN_BUF_SIZE);
> >
> > test(buf, fmt, p);
> > }
> > @@ -739,11 +664,9 @@ flags(void)
> > (unsigned long) gfp);
> > gfp |= __GFP_HIGH;
> > test(cmp_buffer, "%pGg", &gfp);
> > -
> > - kfree(cmp_buffer);
>
> I belive that the kfree() should stay. Otherwise, the test leaks memory
> in every run.

This memory is now allocated using `kunit_kmalloc`:

> * kunit_kmalloc() - Like kmalloc() except the allocation is *test managed*.
> [...]
> * See kmalloc() and kunit_kmalloc_array() for more information.

`kunit_kmalloc_array`:

> * Just like `kmalloc_array(...)`, except the allocation is managed by the test case
> * and is automatically cleaned up after the test case concludes. See kunit_add_action()
> * for more information.

So this kfree is not necessary.

>
> > }
> >
> > -static void fwnode_pointer(void)
> > +static void fwnode_pointer(struct kunit *kunittest)
> > {
> > const struct software_node first = { .name = "first" };
> > const struct software_node second = { .name = "second", .parent = &first };
>
> Otherwise, it looks good to me.
>
> Best Regards,
> Petr