[dpdk-dev] [PATCH] eal: fix argument to rte_bsf32_safe

[dpdk-dev] [PATCH] eal: fix argument to rte_bsf32_safe

[Stephen Hemminger]

The first argument to rte_bsf32_safe was incorrectly declared as
a 64 bit value. This function only correctly handles on 32 bit values
and the underlying function rte_bsf32 only accepts 32 bit values.
This was 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>
---
 lib/eal/include/rte_common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index d5a32c66a5fe..99eb5f1820ae 100644
--- 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;
-- 
2.30.2

Re: [dpdk-dev] [PATCH] eal: fix argument to rte_bsf32_safe

[Tyler Retzlaff]

On Tue, Jul 13, 2021 at 01:12:21PM -0700, Stephen Hemminger wrote:
> The first argument to rte_bsf32_safe was incorrectly declared as
> a 64 bit value. This function only correctly handles on 32 bit values
> and the underlying function rte_bsf32 only accepts 32 bit values.
> This was introduced when the safe version was added and probably cause
> by copy/paste from the 64 bit version.

there are multiple errors in this family of functions [1] both in usage
and signatures. we previously discussed rolling all fixes up into a single
patch and announcing an api break.

a doc patch was submitted as per the process documented for breaking api
but received no replies [2]

i have a full patch that corrects the whole family if you would like to
take it instead. contact me offline if you are interested.

1. http://mails.dpdk.org/archives/dev/2021-March/201590.html
2. http://mails.dpdk.org/archives/dev/2021-March/201868.html

the change stand-alone is correct so

Acked-By: Tyler Retzlaff <roretzla@linux.microsoft.com>

> 
> 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>
> ---
>  lib/eal/include/rte_common.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
> index d5a32c66a5fe..99eb5f1820ae 100644
> --- 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;
> -- 
> 2.30.2

Re: [dpdk-dev] [PATCH] eal: fix argument to rte_bsf32_safe

[Stephen Hemminger]

On Mon, 19 Jul 2021 10:15:34 -0700
Tyler Retzlaff <roretzla@linux.microsoft.com> wrote:

> On Tue, Jul 13, 2021 at 01:12:21PM -0700, Stephen Hemminger wrote:
> > The first argument to rte_bsf32_safe was incorrectly declared as
> > a 64 bit value. This function only correctly handles on 32 bit values
> > and the underlying function rte_bsf32 only accepts 32 bit values.
> > This was introduced when the safe version was added and probably cause
> > by copy/paste from the 64 bit version.  
> 
> there are multiple errors in this family of functions [1] both in usage
> and signatures. we previously discussed rolling all fixes up into a single
> patch and announcing an api break.
> 
> a doc patch was submitted as per the process documented for breaking api
> but received no replies [2]
> 
> i have a full patch that corrects the whole family if you would like to
> take it instead. contact me offline if you are interested.
> 
> 1. http://mails.dpdk.org/archives/dev/2021-March/201590.html
> 2. http://mails.dpdk.org/archives/dev/2021-March/201868.html
> 
> the change stand-alone is correct so
> 
> Acked-By: Tyler Retzlaff <roretzla@linux.microsoft.com>

Thanks, I think the larger set should go into 21.11 where API/ABI break
would be ok. My bit was all about fixing the bug where current code
breaks C++ users.

Re: [dpdk-dev] [PATCH] eal: fix argument to rte_bsf32_safe

[Thomas Monjalon]

20/07/2021 00:00, Stephen Hemminger:
> On Mon, 19 Jul 2021 10:15:34 -0700
> Tyler Retzlaff <roretzla@linux.microsoft.com> wrote:
> 
> > On Tue, Jul 13, 2021 at 01:12:21PM -0700, Stephen Hemminger wrote:
> > > The first argument to rte_bsf32_safe was incorrectly declared as
> > > a 64 bit value. This function only correctly handles on 32 bit values
> > > and the underlying function rte_bsf32 only accepts 32 bit values.
> > > This was introduced when the safe version was added and probably cause
> > > by copy/paste from the 64 bit version.  
> > 
> > there are multiple errors in this family of functions [1] both in usage
> > and signatures. we previously discussed rolling all fixes up into a single
> > patch and announcing an api break.
> > 
> > a doc patch was submitted as per the process documented for breaking api
> > but received no replies [2]
> > 
> > i have a full patch that corrects the whole family if you would like to
> > take it instead. contact me offline if you are interested.
> > 
> > 1. http://mails.dpdk.org/archives/dev/2021-March/201590.html
> > 2. http://mails.dpdk.org/archives/dev/2021-March/201868.html
> > 
> > the change stand-alone is correct so
> > 
> > Acked-By: Tyler Retzlaff <roretzla@linux.microsoft.com>
> 
> Thanks, I think the larger set should go into 21.11 where API/ABI break
> would be ok. My bit was all about fixing the bug where current code
> breaks C++ users.

Shouldn't we have a note in the API changes section of the release notes?

[dpdk-dev] [PATCH v2] eal: fix argument to rte_bsf32_safe

[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 probaly 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>
---
v2 - add suggested release note

 doc/guides/rel_notes/release_21_08.rst | 4 ++++
 lib/eal/include/rte_common.h           | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/doc/guides/rel_notes/release_21_08.rst b/doc/guides/rel_notes/release_21_08.rst
index e2c5ccbf7d90..148405891fcb 100644
--- a/doc/guides/rel_notes/release_21_08.rst
+++ b/doc/guides/rel_notes/release_21_08.rst
@@ -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
 -----------
diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index d5a32c66a5fe..99eb5f1820ae 100644
--- 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;
-- 
2.30.2

[dpdk-dev] [PATCH v3] eal: fix argument to rte_bsf32_safe

[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>
---
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(-)

diff --git a/doc/guides/rel_notes/release_21_08.rst b/doc/guides/rel_notes/release_21_08.rst
index e2c5ccbf7d90..148405891fcb 100644
--- a/doc/guides/rel_notes/release_21_08.rst
+++ b/doc/guides/rel_notes/release_21_08.rst
@@ -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
 -----------
diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index d5a32c66a5fe..99eb5f1820ae 100644
--- 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;
-- 
2.30.2

Re: [dpdk-dev] [PATCH v3] eal: fix argument to rte_bsf32_safe

[Thomas Monjalon]

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.

Re: [dpdk-dev] [PATCH v3] eal: fix argument to rte_bsf32_safe

[Stephen Hemminger]

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.