[v3] eal: fix argument to rte_bsf32_safe
Checks
Commit Message
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: anatoly.burakov@intel.com
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
---
v3 - reword commit description for checkpatch
doc/guides/rel_notes/release_21_08.rst | 4 ++++
lib/eal/include/rte_common.h | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
Comments
23/07/2021 17:45, Stephen Hemminger:
> 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: anatoly.burakov@intel.com
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
+Cc: stable@dpdk.org
Applied, thanks.
I think these functions lack a reference to the name Bit Scan Forward.
On Sat, 24 Jul 2021 09:58:44 +0200
Thomas Monjalon <thomas@monjalon.net> wrote:
> 23/07/2021 17:45, Stephen Hemminger:
> > 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: anatoly.burakov@intel.com
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
>
> +Cc: stable@dpdk.org
>
> Applied, thanks.
>
> I think these functions lack a reference to the name Bit Scan Forward.
>
>
>
>
Tyler wanted to fix a bunch more stuff in these for 21.11 where it will
be a bigger API change.
@@ -196,6 +196,10 @@ API Changes
to be thread safe; all Rx queues affected by the API will now need to be
stopped before making any changes to the power management scheme.
+* 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.
+
ABI Changes
-----------
@@ -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;