Re: [dpdk-dev] [PATCH v3] mbuf: cleanup rte_pktmbuf_lastseg(), fix atomic usage

[Ilya Matveychikov <matvejchikov@gmail.com>]

> On Nov 16, 2017, at 11:16 AM, Hanoch Haim (hhaim) <hhaim@cisco.com> wrote:
> 
> Hi Oliver, 
> 
> It's hard for me to follow this thread. 
> 
> 1)  It is not about clear/not-clear, it is error prone to *replicate* code that has the same logic.
> 
> "I'm not convinced that:
> 
>    __rte_pktmbuf_reset_nb_segs(m);
> 
> is clearer than:
> 
>   m->next = NULL;
>   m->nb_segs = 1;
> 
> Anyway, I agree this should not be part of this patch. We should only keep the fix.
> "
> 2) This definitely does not look good. 
> All the point in my patch is to move the ref-cnt operations to set of API that already taking care of RTE_MBUF_REFCNT_ATOMIC
> 
> +               /* We don't use rte_mbuf_refcnt_update() because we already
> +                * tested that refcnt != 1.
> +                */
> +#ifdef RTE_MBUF_REFCNT_ATOMIC
> +               ret = rte_atomic16_add_return(&m->refcnt_atomic, -1); 
> +#else
> +               ret = --m->refcnt;
> +#endif
> +               if (ret != 0)
> +                       return NULL;
> 

Looks ugly, agreed.