> -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > Sent: Tuesday, May 17, 2016 2:40 PM > To: Ananyev, Konstantin > Cc: dev at dpdk.org; Hiroyuki Mikita; olivier.matz at 6wind.com > Subject: Re: [dpdk-dev] [PATCH v2] mbuf: decrease refcnt when detaching > > 2016-05-17 12:59, Ananyev, Konstantin: > > > > The rte_pktmbuf_detach() function should decrease refcnt on a direct > > > > buffer. > > > > > > As you have noticed, "whenever the indirect buffer is detached, > > > the reference counter on the direct buffer is decremented." > > > So the current behaviour of rte_pktmbuf_detach() is buggy. > > > Why not fix it without renaming? > > > If you consider this behavioral bug is part of the API, we > > > can fix it in a new function unattach and deprecate detach. > > > But Konstantin, why do you want to keep a restore function? > > > What is the need? > > > > I think it might be a useful functionality in some situations: > > some users can attach/detach to external memory buffers (no mbufs) > > and similar functionality is required. > > Attach to external memory buffer (raw buffer) is not currently supported. > > > Let say right now examples/vhost/main.c has its own pktmbuf_detach_zcp() > > You should look at the commit http://dpdk.org/commit/68363d85 > "examples/vhost: remove the non-working zero copy code" > > > which is doing pretty much the same - restore original values, after > > detaching > > mbuf from external (virtio) memory buffer. > > Would be good if we'll use a standard API function here. > > You are welcome to implement mbuf attach to raw buffer. > But it is not a requirement for this fix.
Hmm, still not sure why we can't keep an existing function? Obviously it wouldn't cost anything and I still think might be useful. Konstantin
