Re: [dpdk-dev] [PATCH v2 0/2] Removal of RTE_MBUF_REFCNT

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

> > This patch tries to remove the RTE_MBUF_REFCNT config options and dependencies
> > by introducing a new mbuf flag IND_ATTACHED_MBUF that would indicate when the mbuf
> > is an indirect attached mbuf, to differentiate between indirect mbufs and mbufs
> > with external memory buffers (ie. vhost zero copy).
> > 
> > Previous discussion:
> > http://dpdk.org/ml/archives/dev/2014-October/007127.html
> > 
> > Currently for mbufs with refcnt, we cannot free mbufs with external memory
> > buffers (ie. vhost zero copy), as they are recognized as indirect
> > attached mbufs and therefore we free the direct mbuf it points to,
> > resulting in an error in the case of external memory buffers.
> > 
> > We solve the issue by introducing the IND_ATTACHED_MBUF flag, which indicates
> > that the mbuf is an indirect attached mbuf pointing to another mbuf.
> > When we free an mbuf, we only free the direct mbuf if the flag is set.
> > Freeing an mbuf with external buffer is the same as freeing a non attached mbuf.
> > The flag is set during attach and clear on detach.
> > 
> > So in the case of vhost zero copy where we have mbufs with external
> > buffers, by default we just free the mbuf and it is up to the user to deal with
> > the external buffer.
> > 
> > v2:
> >  - Add missing parenthesis to RTE_MBUF_INDIRECT macro
> > 
> > Sergio Gonzalez Monroy (2):
> >   mbuf: Introduce IND_ATTACHED_MBUF flag
> >   Remove RTE_MBUF_REFCNT references
> 
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

Applied, thanks