From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH] Subject: virtio: Add unused buffers detach from vring Date: Tue, 15 Dec 2009 23:14:50 +0200 Message-ID: <20091215211450.GE26712@redhat.com> References: <1260534506.30371.6.camel@localhost.localdomain> <1260535613.30371.24.camel@localhost.localdomain> <20091213114320.GC7074@redhat.com> <1260828518.8716.105.camel@localhost.localdomain> <20091215113327.GC13110@redhat.com> <1260894320.4387.64.camel@localhost.localdomain> <20091215163901.GA24015@redhat.com> <1260902573.4387.76.camel@localhost.localdomain> <20091215184740.GD25724@redhat.com> <1260904447.4387.85.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Rusty Russell , Avi Kivity , netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Anthony Liguori To: Shirley Ma Return-path: Content-Disposition: inline In-Reply-To: <1260904447.4387.85.camel@localhost.localdomain> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Dec 15, 2009 at 11:14:07AM -0800, Shirley Ma wrote: > Hello Michael, > > On Tue, 2009-12-15 at 20:47 +0200, Michael S. Tsirkin wrote: > > > + detach_buf(vq, i); > > > + END_USE(vq); > > > + return vq->data[i]; > > > > In fact, this will return NULL always, won't it? > > Nope, I changed the destroy to detach and return the buffers without > destroying them within the call. I thought it might be useful in some > other case. > > Maybe I should put destroy call back? > > Thanks > Shirley No I think it's good as is, we do not need a callback. I was simply saying that detach_buf sets data to NULL, so return vq->data[i] after detach does not make sense. You need to save data as comment below says.c -- MST