eal: fix argument in 32-bit safe BSF function

The first argument to rte_bsf32_safe was incorrectly declared as
a 64 bit value. The code only works on 32 bit values and the underlying
function rte_bsf32 only accepts 32 bit values. This was a mistake
introduced when the safe version was added and probably cause
by copy/paste from the 64 bit version.

The bug passed silently under the radar until some other code was
built with -Wall and -Wextra in C++ and C++ complains about the
missing cast.

Yes, this is a API signature change, but the original code was wrong.
It is an inline so not an ABI change.

Fixes: 4e261f551986 ("eal: add 64-bit bsf and 32-bit safe bsf functions")
Cc: stable@dpdk.org
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

diff --git a/doc/guides/rel_notes/release_21_08.rst b/doc/guides/rel_notes/release_21_08.rst
index 9904a0e..de76d69 100644 (file)
--- a/doc/guides/rel_notes/release_21_08.rst
+++ b/doc/guides/rel_notes/release_21_08.rst
@@ -202,6 +202,10 @@ API Changes
 * eal: ``rte_strscpy`` sets ``rte_errno`` to ``E2BIG`` in case of string
   truncation.
 
+* eal: ``rte_bsf32_safe`` now takes a 32-bit value for its first argument.
+  This fixes warnings about loss of precision
+  when used with some compilers settings.
+
 * eal: ``rte_power_monitor`` and the ``rte_power_monitor_cond`` struct changed
   to use a callback mechanism.
 

diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index d5a32c6..99eb5f1 100644 (file)
--- a/lib/eal/include/rte_common.h
+++ b/lib/eal/include/rte_common.h
@@ -623,7 +623,7 @@ rte_bsf32(uint32_t v)
  *     Returns 0 if ``v`` was 0, otherwise returns 1.
  */
 static inline int
-rte_bsf32_safe(uint64_t v, uint32_t *pos)
+rte_bsf32_safe(uint32_t v, uint32_t *pos)
 {
        if (v == 0)
                return 0;