Re: [dpdk-dev] [PATCH] examples/l3fwd: fix segfault with gcc 5.x

[Thomas Monjalon <thomas.monjalon@6wind.com>]

> > It seems that with gcc >5.x and -O2/-O3 optimization breaks packet grouping
> > algorithm.
> > 
> > When last packet pointer "lp" and "pnum->u64" buffer points the same
> > memory buffer, high optimization can cause unpredictable results. It seems
> > that assignment of precalculated group sizes may interfere with
> > initialization of new group size when lp points value inside current group
> > and didn't should be changed.
> > 
> > With gcc >5.x and optimization we cannot be sure which assignment will be
> > done first, so the group size can be counted incorrectly.
> > 
> > This patch eliminates intersection of assignment of initial group size
> > (lp[0] = 1) and precalculated group sizes when gptbl[v].idx < 4.
> > 
> > Fixes: 94c54b4158d5 ("examples/l3fwd: rework exact-match")
> > 
> > Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
> 
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

Applied, thanks