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

[Olivier Matz <olivier.matz@6wind.com>]

On Mon, May 03, 2021 at 04:21:25PM +0200, David Marchand wrote:
> 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?

Agreed.