Re: [PATCH] selftests/nolibc: add 7 tests for memcmp()

From: "Paul E. McKenney" <paulmck@kernel.org>
To: Willy Tarreau <w@1wt.eu>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] selftests/nolibc: add 7 tests for memcmp()
Date: Fri, 21 Oct 2022 08:56:45 -0700	[thread overview]
Message-ID: <20221021155645.GK5600@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <20221021060340.7515-1-w@1wt.eu>

On Fri, Oct 21, 2022 at 08:03:40AM +0200, Willy Tarreau wrote:
> This adds 7 combinations of input values for memcmp() using signed and
> unsigned bytes, which will trigger on the original code before Rasmus'
> fix. This is mostly aimed at helping backporters verify their work, and
> showing how tests for corner cases can be added to the selftests suite.
> 
> Before the fix it reports:
>   12 memcmp_20_20 = 0                      [OK]
>   13 memcmp_20_60 = -64                    [OK]
>   14 memcmp_60_20 = 64                     [OK]
>   15 memcmp_20_e0 = 64                    [FAIL]
>   16 memcmp_e0_20 = -64                   [FAIL]
>   17 memcmp_80_e0 = -96                    [OK]
>   18 memcmp_e0_80 = 96                     [OK]
> 
> And after:
>   12 memcmp_20_20 = 0                      [OK]
>   13 memcmp_20_60 = -64                    [OK]
>   14 memcmp_60_20 = 64                     [OK]
>   15 memcmp_20_e0 = -192                   [OK]
>   16 memcmp_e0_20 = 192                    [OK]
>   17 memcmp_80_e0 = -96                    [OK]
>   18 memcmp_e0_80 = 96                     [OK]
> 
> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Signed-off-by: Willy Tarreau <w@1wt.eu>

I have pulled both of these in, thank you!

One thing, though...  I had to do "make clean" in both tools/include/nolibc
and tools/testing/selftests/nolibc to make those two "[FAIL]" indications
go away.  Does this mean that I am doing something wrong?

It would be good to know before I send the pull request containing these,
so that we can let Linus know of anything special he needs to do to
ensure a valid test result.

							Thanx, Paul

> ---
>  tools/testing/selftests/nolibc/nolibc-test.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
> index 78bced95ac63..f14f5076fb6d 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -565,6 +565,13 @@ int run_stdlib(int min, int max)
>  		CASE_TEST(strchr_foobar_z);    EXPECT_STRZR(1, strchr("foobar", 'z')); break;
>  		CASE_TEST(strrchr_foobar_o);   EXPECT_STREQ(1, strrchr("foobar", 'o'), "obar"); break;
>  		CASE_TEST(strrchr_foobar_z);   EXPECT_STRZR(1, strrchr("foobar", 'z')); break;
> +		CASE_TEST(memcmp_20_20);       EXPECT_EQ(1, memcmp("aaa\x20", "aaa\x20", 4), 0); break;
> +		CASE_TEST(memcmp_20_60);       EXPECT_LT(1, memcmp("aaa\x20", "aaa\x60", 4), 0); break;
> +		CASE_TEST(memcmp_60_20);       EXPECT_GT(1, memcmp("aaa\x60", "aaa\x20", 4), 0); break;
> +		CASE_TEST(memcmp_20_e0);       EXPECT_LT(1, memcmp("aaa\x20", "aaa\xe0", 4), 0); break;
> +		CASE_TEST(memcmp_e0_20);       EXPECT_GT(1, memcmp("aaa\xe0", "aaa\x20", 4), 0); break;
> +		CASE_TEST(memcmp_80_e0);       EXPECT_LT(1, memcmp("aaa\x80", "aaa\xe0", 4), 0); break;
> +		CASE_TEST(memcmp_e0_80);       EXPECT_GT(1, memcmp("aaa\xe0", "aaa\x80", 4), 0); break;
>  		case __LINE__:
>  			return ret; /* must be last */
>  		/* note: do not set any defaults so as to permit holes above */
> -- 
> 2.17.5
> 