Re: [dpdk-dev] [PATCH v1] doc: update atomic operation deprecation

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

<snip>

> 
> Update the incorrect description about atomic operations with provided
> wrappers in deprecation doc[1].
> 
> [1]https://mails.dpdk.org/archives/dev/2021-July/213333.html
> 
> Fixes: 7518c5c4ae6a ("doc: announce adoption of C11 atomic operations
> semantics")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Joyce Kong <joyce.kong@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
>  doc/guides/rel_notes/deprecation.rst | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst
> b/doc/guides/rel_notes/deprecation.rst
> index 9584d6bfd7..4142315842 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -19,16 +19,16 @@ Deprecation Notices
> 
>  * rte_atomicNN_xxx: These APIs do not take memory order parameter. This
> does
>    not allow for writing optimized code for all the CPU architectures supported
> -  in DPDK. DPDK will adopt C11 atomic operations semantics and provide
> wrappers
> -  using C11 atomic built-ins. These wrappers must be used for patches that
> -  need to be merged in 20.08 onwards. This change will not introduce any
> -  performance degradation.
> +  in DPDK. DPDK has adopted atomic operations semantics. GCC atomic
> + built-ins  must be used for patches that need to be merged in 20.08
> + onwards. This change  will not introduce any performance degradation.
Since there have been objections to the language used to refer to GCC C11 atomic built-ins, may be we add a reference to the GCC pages?

DPDK has adopted the atomic operations from https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html. These operations must be used for patches that need to be merged in 20.08 onwards. This change  will not introduce any performance degradation.

> 
>  * rte_smp_*mb: These APIs provide full barrier functionality. However, many
> -  use cases do not require full barriers. To support such use cases, DPDK will
> -  adopt C11 barrier semantics and provide wrappers using C11 atomic built-
> ins.
> -  These wrappers must be used for patches that need to be merged in 20.08
> -  onwards. This change will not introduce any performance degradation.
> +  use cases do not require full barriers. To support such use cases,
> + DPDK has  adopted atomic barrier semantics. GCC atomic built-ins and a
> + new wrapper  ``rte_atomic_thread_fence`` instead of
> + ``__atomic_thread_fence`` must be  used for patches that need to be
> + merged in 20.08 onwards. This change will  not introduce any performance
> degradation.
Same here.
To support such use cases, DPDK has  adopted atomic operations from https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html. A new wrapper  ``rte_atomic_thread_fence`` instead of ``__atomic_thread_fence`` must be  used for patches that need to be merged in 20.08 onwards. This change will  not introduce any performance degradation.

> 
>  * lib: will fix extending some enum/define breaking the ABI. There are
> multiple
>    samples in DPDK that enum/define terminated with a ``.*MAX.*`` value
> which is
> --
> 2.17.1