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[2003:d0:af41:6e00:eb84:418c:678a:bf7e]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae3f6b64f5asm166346066b.162.2025.07.04.05.52.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jul 2025 05:52:40 -0700 (PDT) From: Markus Theil To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: davem@davemloft.net, akpm@linux-foundation.org, Jason@zx2c4.com, Markus Theil Subject: [PATCH v2 4/4] test_hash.c: replace custom PRNG by prandom Date: Fri, 4 Jul 2025 14:52:33 +0200 Message-ID: <20250704125233.2653779-5-theil.markus@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250704125233.2653779-1-theil.markus@gmail.com> References: <20250704125233.2653779-1-theil.markus@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use default PRNG, as there is no real need for a custom solution here. We know the sequence provided by our seed and do not need to do bit magic in order to obtain a non-zero byte. Just iterate a small number of times, if needed. Signed-off-by: Markus Theil --- lib/tests/test_hash.c | 40 +++++++++++++--------------------------- 1 file changed, 13 insertions(+), 27 deletions(-) diff --git a/lib/tests/test_hash.c b/lib/tests/test_hash.c index a7af39662a0a..308446ea3431 100644 --- a/lib/tests/test_hash.c +++ b/lib/tests/test_hash.c @@ -17,39 +17,21 @@ #include #include #include +#include #include #include #include =20 -/* 32-bit XORSHIFT generator. Seed must not be zero. */ -static u32 __attribute_const__ -xorshift(u32 seed) -{ - seed ^=3D seed << 13; - seed ^=3D seed >> 17; - seed ^=3D seed << 5; - return seed; -} - -/* Given a non-zero x, returns a non-zero byte. */ -static u8 __attribute_const__ -mod255(u32 x) -{ - x =3D (x & 0xffff) + (x >> 16); /* 1 <=3D x <=3D 0x1fffe */ - x =3D (x & 0xff) + (x >> 8); /* 1 <=3D x <=3D 0x2fd */ - x =3D (x & 0xff) + (x >> 8); /* 1 <=3D x <=3D 0x100 */ - x =3D (x & 0xff) + (x >> 8); /* 1 <=3D x <=3D 0xff */ - return x; -} - /* Fill the buffer with non-zero bytes. */ -static void fill_buf(char *buf, size_t len, u32 seed) +static void fill_buf(char *buf, size_t len, struct rnd_state *prng) { size_t i; =20 for (i =3D 0; i < len; i++) { - seed =3D xorshift(seed); - buf[i] =3D mod255(seed); + /* we know our seeds, no need to worry about endless runtime */ + do { + buf[i] =3D (u8) prandom_u32_state(prng); + } while (!buf[i]); } } =20 @@ -143,11 +125,13 @@ test_int_hash(struct kunit *test, unsigned long long = h64, u32 hash_or[2][33]) =20 static void test_string_or(struct kunit *test) { - char buf[SIZE+1]; + struct rnd_state prng; u32 string_or =3D 0; + char buf[SIZE+1]; int i, j; =20 - fill_buf(buf, SIZE, 1); + prandom_seed_state(&prng, 0x1); + fill_buf(buf, SIZE, &prng); =20 /* Test every possible non-empty substring in the buffer. */ for (j =3D SIZE; j > 0; --j) { @@ -171,9 +155,11 @@ static void test_hash_or(struct kunit *test) char buf[SIZE+1]; u32 hash_or[2][33] =3D { { 0, } }; unsigned long long h64 =3D 0; + struct rnd_state prng; int i, j; =20 - fill_buf(buf, SIZE, 1); + prandom_seed_state(&prng, 0x1); + fill_buf(buf, SIZE, &prng); =20 /* Test every possible non-empty substring in the buffer. */ for (j =3D SIZE; j > 0; --j) { --=20 2.49.0