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From: David Marchand <david.marchand@redhat.com>
To: dev@dpdk.org
Cc: aconole@redhat.com,
stable@dpdk.org
Date: Fri, 20 Dec 2019 15:01:49 +0100
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Subject: [dpdk-dev] [PATCH v2] test/common: fix log2 check
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We recently started to get random failures on the common_autotest ut with
clang on Ubuntu 16.04.6.
Example: https://travis-ci.com/DPDK/dpdk/jobs/263177424
Wrong rte_log2_u64(0) val 0, expected ffffffff
Test Failed
The ut passes 0 to log2() to get an expected value.
Quoting log2 / log(3) manual:
If x is zero, then a pole error occurs, and the functions return
-HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.
rte_log2_uXX helpers handle 0 as a special value and return 0.
Let's have dedicated tests for this case.
Fixes: 05c4345ef5c2 ("test: add unit test for integer log2 function")
Cc: stable@dpdk.org
Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Aaron Conole <aconole@redhat.com>
---
Changelog since v1:
- added comment in rte_log2_uXX API descriptions,
---
app/test/test_common.c | 14 +++++++++++++-
lib/librte_eal/common/include/rte_common.h | 6 ++++++
2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/app/test/test_common.c b/app/test/test_common.c
index 2b856f8ba5..12bd1cad90 100644
--- a/app/test/test_common.c
+++ b/app/test/test_common.c
@@ -216,7 +216,19 @@ test_log2(void)
=09const uint32_t max =3D 0x10000;
=09const uint32_t step =3D 1;
=20
-=09for (i =3D 0; i < max; i =3D i + step) {
+=09compare =3D rte_log2_u32(0);
+=09if (compare !=3D 0) {
+=09=09printf("Wrong rte_log2_u32(0) val %x, expected 0\n", compare);
+=09=09return TEST_FAILED;
+=09}
+
+=09compare =3D rte_log2_u64(0);
+=09if (compare !=3D 0) {
+=09=09printf("Wrong rte_log2_u64(0) val %x, expected 0\n", compare);
+=09=09return TEST_FAILED;
+=09}
+
+=09for (i =3D 1; i < max; i =3D i + step) {
=09=09uint64_t i64;
=20
=09=09/* extend range for 64-bit */
diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/co=
mmon/include/rte_common.h
index 459d082d14..7a98071ffe 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -538,6 +538,9 @@ rte_bsf32_safe(uint64_t v, uint32_t *pos)
/**
* Return the rounded-up log2 of a integer.
*
+ * @note Contrary to the logarithm mathematical operation,
+ * rte_log2_u32(0) =3D=3D 0 and not -inf.
+ *
* @param v
* The input parameter.
* @return
@@ -632,6 +635,9 @@ rte_fls_u64(uint64_t x)
/**
* Return the rounded-up log2 of a 64-bit integer.
*
+ * @note Contrary to the logarithm mathematical operation,
+ * rte_log2_u32(0) =3D=3D 0 and not -inf.
+ *
* @param v
* The input parameter.
* @return
--=20
2.23.0