Re: [dpdk-dev] [PATCH 0/3] add lock-free stack support discovery

[David Marchand <david.marchand@redhat.com>]

On Mon, Apr 12, 2021 at 10:29 AM Stanislaw Kardach <kda@semihalf.com> wrote:
>
> The lock-free stack implementation (RTE_STACK_F_LF) is supported only on a
> subset of platforms, namely x86_64 and arm64. Platforms supporting 128b atomics
> have to opt-in to a generic or C11 implementations. All other platforms use a
> stubbed implementation for push/pop operations which are basically NOPs.
> However rte_stack_create() will not fail and application can proceed assuming
> it has a working lock-free stack.
>
> This means that among other things the stack_lf fast and perf tests will fail
> as if implementation is wrong (which one can argue is). Therefore this patchset
> tries to give user a way to check whether a lock_free is supported or not both
> at compile time (build flag) and at runtime (ENOTSUP errno in rte_stack_create).
>
> I have added cc to stable@dpdk.org because check-git-log.sh suggested it. I'm
> not sure if adding a binary compatible change to API is worth stable@dpdk.org.
>
> Cc: stable@dpdk.org

The issue was hit while porting to a new architecture.
The feature is broken in existing stable releases and it won't get
fixed by this change.

I'd rather not backport it.

Opinions?


-- 
David Marchand