Re: [PATCH v2 5/5] test_hash.c: refactor into kunit

[Isabella B do Amaral]

Hi, David,

On Sat, Oct 2, 2021 at 4:22 AM David Gow <davidgow@xxxxxxxxxx> wrote:
>
> On Mon, Sep 27, 2021 at 6:33 AM Isabella Basso <isabellabdoamaral@xxxxxx> wrote:
> >
> > Use KUnit framework to make tests more easily integrable with CIs. Even
> > though these tests are not yet properly written as unit tests this
> > change should help in debugging.
> >
> > Also remove kernel messages (i.e. through pr_info) as KUnit handles all
> > debugging output and let it handle module init and exit details.
> >
> > Changes since v1:
> > - As suggested by David Gow:
> >   1. Keep module support.
> >   2. Reword commit message.
> > - As reported by the kernel test bot:
> >   1. Fix compilation for m68k and parisc architectures.
> >
>
> It might be worth moving the changelog under the "---" here, so that
> it's not a part of the final commit message.
>
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Tested-by: David Gow <davidgow@xxxxxxxxxx>
> > Co-developed-by: Augusto Durães Camargo <augusto.duraes33@xxxxxxxxx>
> > Signed-off-by: Augusto Durães Camargo <augusto.duraes33@xxxxxxxxx>
> > Co-developed-by: Enzo Ferreira <ferreiraenzoa@xxxxxxxxx>
> > Signed-off-by: Enzo Ferreira <ferreiraenzoa@xxxxxxxxx>
> > Signed-off-by: Isabella Basso <isabellabdoamaral@xxxxxx>
> > ---
>
> I went through this in a little more detail, and I'm happy with it.
> It'd still be nice if someone with more knowledge of the hashing code
> looked over it, but since George's email bounced, I'm happy to give
> this my reviewed-by.
>
> There are a few minor comments below (and above, I guess), which would
> be worth doing as part of a v3.
>
> Reviewed-by: David Gow <davidgow@xxxxxxxxxx>
>
> Thanks,
> -- David
>
> >  lib/Kconfig.debug |  28 ++++---
> >  lib/Makefile      |   2 +-
> >  lib/test_hash.c   | 187 ++++++++++++++--------------------------------
> >  3 files changed, 78 insertions(+), 139 deletions(-)
> >
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index eb6c4daf5fcb..04eec87c2964 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -2204,15 +2204,6 @@ config TEST_RHASHTABLE
> >
> >           If unsure, say N.
> >
> > -config TEST_HASH
> > -       tristate "Perform selftest on hash functions"
> > -       help
> > -         Enable this option to test the kernel's integer (<linux/hash.h>), and
> > -         string (<linux/stringhash.h>) hash functions on boot (or module load).
> > -
> > -         This is intended to help people writing architecture-specific
> > -         optimized versions.  If unsure, say N.
> > -
> >  config TEST_SIPHASH
> >         tristate "Perform selftest on siphash functions"
> >         help
> > @@ -2361,6 +2352,25 @@ config BITFIELD_KUNIT
> >
> >           If unsure, say N.
> >
> > +config HASH_KUNIT_TEST
> > +       tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
> > +       depends on KUNIT
> > +       default KUNIT_ALL_TESTS
> > +       help
> > +         Enable this option to test the kernel's string (<linux/stringhash.h>), and
> > +         integer (<linux/hash.h>) hash functions on boot.
> > +
> > +         KUnit tests run during boot and output the results to the debug log
> > +         in TAP format (https://testanything.org/). Only useful for kernel devs
> > +         running the KUnit test harness, and not intended for inclusion into a
> > +         production build.
> > +
> > +         For more information on KUnit and unit tests in general please refer
> > +         to the KUnit documentation in Documentation/dev-tools/kunit/.
> > +
> > +         This is intended to help people writing architecture-specific
> > +         optimized versions. If unsure, say N.
> > +
> >  config RESOURCE_KUNIT_TEST
> >         tristate "KUnit test for resource API"
> >         depends on KUNIT
> > diff --git a/lib/Makefile b/lib/Makefile
> > index c2e81d0eb31c..0bc336d9d036 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -62,7 +62,7 @@ obj-$(CONFIG_TEST_BITOPS) += test_bitops.o
> >  CFLAGS_test_bitops.o += -Werror
> >  obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o
> >  obj-$(CONFIG_TEST_SIPHASH) += test_siphash.o
> > -obj-$(CONFIG_TEST_HASH) += test_hash.o
> > +obj-$(CONFIG_HASH_KUNIT_TEST) += test_hash.o
> >  obj-$(CONFIG_TEST_IDA) += test_ida.o
> >  obj-$(CONFIG_KASAN_KUNIT_TEST) += test_kasan.o
> >  CFLAGS_test_kasan.o += -fno-builtin
> > diff --git a/lib/test_hash.c b/lib/test_hash.c
> > index db9dd18b4e8b..9cb8b1d2ab06 100644
> > --- a/lib/test_hash.c
> > +++ b/lib/test_hash.c
> > @@ -14,14 +14,12 @@
> >   * and hash_64().
> >   */
> >
> > -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n"
> > -
> >  #include <linux/compiler.h>
> >  #include <linux/types.h>
> >  #include <linux/module.h>
> >  #include <linux/hash.h>
> >  #include <linux/stringhash.h>
> > -#include <linux/printk.h>
> > +#include <kunit/test.h>
> >
> >  /* 32-bit XORSHIFT generator.  Seed must not be zero. */
> >  static u32 __init __attribute_const__
> > @@ -66,40 +64,32 @@ struct test_hash_params {
> >  };
> >
> >  #ifdef HAVE_ARCH__HASH_32
> > -static bool __init
> > -test_int__hash_32(struct test_hash_params *params)
> > +static void __init
>
> Let's get rid of the __init bits here: it's possible KUnit tests will
> execute after kernel and/or module initialisation.

That makes sense! I thought those were necessary for some reason, my bad.

>
> > +test_int__hash_32(struct kunit *test, struct test_hash_params *params)
> >  {
> >         params->hash_or[1][0] |= params->h2 = __hash_32_generic(params->h0);
> >  #if HAVE_ARCH__HASH_32 == 1
> > -       if (params->h1 != params->h2) {
> > -               pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
> > -                      params->h0, params->h1, params->h2);
> > -               return false;
> > -       }
> > +       KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
> > +                           "__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
> > +                           params->h0, params->h1, params->h2);
> >  #endif
> > -       return true;
> >  }
> >  #endif
> >
> >  #ifdef HAVE_ARCH_HASH_64
> > -static bool __init
> > -test_int_hash_64(struct test_hash_params *params, u32 const *m, int *k)
> > +static void __init
>
> Ditto for all other functions in this file: remove the __init.
>
> > +test_int_hash_64(struct kunit *test, struct test_hash_params *params, u32 const *m, int *k)
> >  {
> >         params->h2 = hash_64_generic(*params->h64, *k);
> >  #if HAVE_ARCH_HASH_64 == 1
> > -       if (params->h1 != params->h2) {
> > -               pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x",
> > -                      *params->h64, *k, params->h1, params->h2);
> > -               return false;
> > -       }
> > +       KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
> > +                           "hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x",
> > +                           *params->h64, *k, params->h1, params->h2);
> >  #else
> > -       if (params->h2 > *m) {
> > -               pr_err("hash_64_generic(%#llx, %d) = %#x > %#x",
> > -                      *params->h64, *k, params->h1, *m);
> > -               return false;
> > -       }
> > +       KUNIT_EXPECT_LE_MSG(test, params->h1, params->h2,
> > +                           "hash_64_generic(%#llx, %d) = %#x > %#x",
> > +                           *params->h64, *k, params->h1, *m);
> >  #endif
> > -       return true;
> >  }
> >  #endif
> >
> > @@ -112,8 +102,8 @@ test_int_hash_64(struct test_hash_params *params, u32 const *m, int *k)
> >   * inline, the code being tested is actually in the module, and you can
> >   * recompile and re-test the module without rebooting.
> >   */
> > -static bool __init
> > -test_int_hash(unsigned long long h64, u32 hash_or[2][33])
> > +static void __init
> > +test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33])
> >  {
> >         int k;
> >         struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or };
> > @@ -121,8 +111,7 @@ test_int_hash(unsigned long long h64, u32 hash_or[2][33])
> >         /* Test __hash32 */
> >         hash_or[0][0] |= params.h1 = __hash_32(params.h0);
> >  #ifdef HAVE_ARCH__HASH_32
> > -       if (!test_int__hash_32(&params))
> > -               return false;
> > +       test_int__hash_32(test, &params);
> >  #endif
> >
> >         /* Test k = 1..32 bits */
> > @@ -131,29 +120,24 @@ test_int_hash(unsigned long long h64, u32 hash_or[2][33])
> >
> >                 /* Test hash_32 */
> >                 hash_or[0][k] |= params.h1 = hash_32(params.h0, k);
> > -               if (params.h1 > m) {
> > -                       pr_err("hash_32(%#x, %d) = %#x > %#x", params.h0, k, params.h1, m);
> > -                       return false;
> > -               }
> > +               KUNIT_EXPECT_LE_MSG(test, params.h1, m,
> > +                                   "hash_32(%#x, %d) = %#x > %#x",
> > +                                   params.h0, k, params.h1, m);
> >
> >                 /* Test hash_64 */
> >                 hash_or[1][k] |= params.h1 = hash_64(h64, k);
> > -               if (params.h1 > m) {
> > -                       pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, params.h1, m);
> > -                       return false;
> > -               }
> > +               KUNIT_EXPECT_LE_MSG(test, params.h1, m,
> > +                                   "hash_64(%#llx, %d) = %#x > %#x",
> > +                                   h64, k, params.h1, m);
> >  #ifdef HAVE_ARCH_HASH_64
> > -               if (!test_int_hash_64(&params, &m, &k))
> > -                       return false;
> > +               test_int_hash_64(test, &params, &m, &k);
> >  #endif
> >         }
> > -
> > -       return true;
> >  }
> >
> >  #define SIZE 256       /* Run time is cubic in SIZE */
> >
> > -static int __init test_string_or(void)
> > +static void __init test_string_or(struct kunit *test)
> >  {
> >         char buf[SIZE+1];
> >         u32 string_or = 0;
> > @@ -173,20 +157,15 @@ static int __init test_string_or(void)
> >         } /* j */
> >
> >         /* The OR of all the hash values should cover all the bits */
> > -       if (~string_or) {
> > -               pr_err("OR of all string hash results = %#x != %#x",
> > -                      string_or, -1u);
> > -               return -EINVAL;
> > -       }
> > -
> > -       return 0;
> > +       KUNIT_EXPECT_FALSE_MSG(test, ~string_or,
> > +                              "OR of all string hash results = %#x != %#x",
> > +                              string_or, -1u);
>
> It might be worth using KUNIT_EXPECT_EQ_MSG() instead of
> EXPECT_FALSE(), as the real goal of this is to check if all bits are
> set.
>
> This'd look something like:
> KUNIT_EXPECT_EQ_MSG(test, string_or, -1u, "OR of all string hash
> results = %#x != %#x", string_or, -1u);

That makes a lot of sense to me. Thanks for the suggestion :)

>
> If instead we checked if string_or == -1u, I think it'd be clearer and
> match the message better. (In fact, I think you could get away with
> removing the message and using the non-_MSG variants if you really
> wanted, though the extra text describing it as the OR of all string
> results is better.)

I like the text as well, as these tests are not really well separated I think
it makes sense keeping them.

>
> >  }
> >
> > -static int __init test_hash_or(void)
> > +static void __init test_hash_or(struct kunit *test)
> >  {
> >         char buf[SIZE+1];
> >         u32 hash_or[2][33] = { { 0, } };
> > -       unsigned tests = 0;
> >         unsigned long long h64 = 0;
> >         int i, j;
> >
> > @@ -201,39 +180,27 @@ static int __init test_hash_or(void)
> >                         u32 h0 = full_name_hash(buf+i, buf+i, j-i);
> >
> >                         /* Check that hashlen_string gets the length right */
> > -                       if (hashlen_len(hashlen) != j-i) {
> > -                               pr_err("hashlen_string(%d..%d) returned length"
> > -                                       " %u, expected %d",
> > -                                       i, j, hashlen_len(hashlen), j-i);
> > -                               return -EINVAL;
> > -                       }
> > +                       KUNIT_EXPECT_EQ_MSG(test, hashlen_len(hashlen), j-i,
> > +                                           "hashlen_string(%d..%d) returned length %u, expected %d",
> > +                                           i, j, hashlen_len(hashlen), j-i);
> >                         /* Check that the hashes match */
> > -                       if (hashlen_hash(hashlen) != h0) {
> > -                               pr_err("hashlen_string(%d..%d) = %08x != "
> > -                                       "full_name_hash() = %08x",
> > -                                       i, j, hashlen_hash(hashlen), h0);
> > -                               return -EINVAL;
> > -                       }
> > +                       KUNIT_EXPECT_EQ_MSG(test, hashlen_hash(hashlen), h0,
> > +                                           "hashlen_string(%d..%d) = %08x != full_name_hash() = %08x",
> > +                                           i, j, hashlen_hash(hashlen), h0);
> >
> >                         h64 = h64 << 32 | h0;   /* For use with hash_64 */
> > -                       if (!test_int_hash(h64, hash_or))
> > -                               return -EINVAL;
> > -                       tests++;
> > +                       test_int_hash(test, h64, hash_or);
> >                 } /* i */
> >         } /* j */
> >
> > -       if (~hash_or[0][0]) {
> > -               pr_err("OR of all __hash_32 results = %#x != %#x",
> > -                       hash_or[0][0], -1u);
> > -               return -EINVAL;
> > -       }
> > +       KUNIT_EXPECT_FALSE_MSG(test, ~hash_or[0][0],
>
> As above, maybe KUNIT_EXPECT_EQ_MSG() instead. (And ditto for all
> similar checks against ~hash_or[...])?
>
>
> > +                              "OR of all __hash_32 results = %#x != %#x",
> > +                              hash_or[0][0], -1u);
> >  #ifdef HAVE_ARCH__HASH_32
> >  #if HAVE_ARCH__HASH_32 != 1    /* Test is pointless if results match */
> > -       if (~hash_or[1][0]) {
> > -               pr_err("OR of all __hash_32_generic results = %#x != %#x",
> > -                       hash_or[1][0], -1u);
> > -               return -EINVAL;
> > -       }
> > +       KUNIT_EXPECT_FALSE_MSG(test, ~hash_or[1][0],
> > +                              "OR of all __hash_32_generic results = %#x != %#x",
> > +                              hash_or[1][0], -1u);
> >  #endif
> >  #endif
> >
> > @@ -241,65 +208,27 @@ static int __init test_hash_or(void)
> >         for (i = 1; i <= 32; i++) {
> >                 u32 const m = ((u32)2 << (i-1)) - 1;    /* Low i bits set */
> >
> > -               if (hash_or[0][i] != m) {
> > -                       pr_err("OR of all hash_32(%d) results = %#x "
> > -                               "(%#x expected)", i, hash_or[0][i], m);
> > -                       return -EINVAL;
> > -               }
> > -               if (hash_or[1][i] != m) {
> > -                       pr_err("OR of all hash_64(%d) results = %#x "
> > -                               "(%#x expected)", i, hash_or[1][i], m);
> > -                       return -EINVAL;
> > -               }
> > +               KUNIT_EXPECT_EQ_MSG(test, hash_or[0][i], m,
> > +                                   "OR of all hash_32(%d) results = %#x (%#x expected)",
> > +                                   i, hash_or[0][i], m);
> > +               KUNIT_EXPECT_EQ_MSG(test, hash_or[1][i], m,
> > +                                   "OR of all hash_64(%d) results = %#x (%#x expected)",
> > +                                   i, hash_or[1][i], m);
> >         }
> > -
> > -       pr_notice("%u tests passed.", tests);
> > -
> > -       return 0;
> > -}
> > -
> > -static void __init notice_skipped_tests(void)
> > -{
> > -       /* Issue notices about skipped tests. */
> > -#ifdef HAVE_ARCH__HASH_32
> > -#if HAVE_ARCH__HASH_32 != 1
> > -       pr_info("__hash_32() is arch-specific; not compared to generic.");
> > -#endif
> > -#else
> > -       pr_info("__hash_32() has no arch implementation to test.");
> > -#endif
> > -#ifdef HAVE_ARCH_HASH_64
> > -#if HAVE_ARCH_HASH_64 != 1
> > -       pr_info("hash_64() is arch-specific; not compared to generic.");
> > -#endif
> > -#else
> > -       pr_info("hash_64() has no arch implementation to test.");
> > -#endif
> >  }
> >
> > -static int __init
> > -test_hash_init(void)
> > -{
> > -       int ret;
> > -
> > -       ret = test_string_or();
> > -       if (ret < 0)
> > -               return ret;
> > -
> > -       ret = test_hash_or();
> > -       if (ret < 0)
> > -               return ret;
> > -
> > -       notice_skipped_tests();
> > +static struct kunit_case hash_test_cases[] __refdata = {
> > +       KUNIT_CASE(test_string_or),
> > +       KUNIT_CASE(test_hash_or),
> > +       {}
> > +};
> >
> > -       return ret;
> > -}
> > +static struct kunit_suite hash_test_suite = {
> > +       .name = "hash",
> > +       .test_cases = hash_test_cases,
> > +};
> >
> > -static void __exit test_hash_exit(void)
> > -{
> > -}
> >
> > -module_init(test_hash_init);   /* Does everything */
> > -module_exit(test_hash_exit);   /* Does nothing */
> > +kunit_test_suite(hash_test_suite);
> >
> >  MODULE_LICENSE("GPL");
> > --
> > 2.33.0
> >

Again, thanks for your review!

Cheers,
--
Isabella Basso