Re: [PATCH v5] net: optimize raw checksum computation

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 8 Jan 2026 16:19:37 -0500
Scott Mitchell <scott.k.mitch1@gmail.com> wrote:

> On Thu, Jan 8, 2026 at 11:12 AM Stephen Hemminger
> <stephen@networkplumber.org> wrote:
> >
> > On Thu,  8 Jan 2026 01:13:38 -0500
> > scott.k.mitch1@gmail.com wrote:
> >  
> > > +#ifdef RTE_CC_GCC
> > > +     /* Suppress GCC -Wmaybe-uninitialized false positive. No assembly/runtime impacts. */
> > > +     asm volatile("" : "+m" (psd_hdr));
> > > +#endif
> > >  
> >
> > Maybe rte_compiler_barrier() will do same thing?  
> 
> Agreed it feels like a compiler bug but looking for advice if I'm
> missing something :)
> 
> My initial concern with rte_compiler_barrier is its a general barrier
> which may have broader impacts on
> optimizations and compiled code. Will that be an issue in this case? I
> wasn't sure and the approach
> in the patch is targeted at a specific variable and assembly from
> clang/gcc was the same. I will
> introduce a macro to make it cleaner and I can replace it with
> rte_compiler_barrier if preferred.

Maybe try with -fanalyzer and it might tell you more.
I suspect some of the aliasing setting are causing issues.
Some drivers are turning on no-strict-aliasing