> -----Original Message----- > From: Wei Liu <wei....@kernel.org> > Sent: 23 December 2019 11:36 > To: Durrant, Paul <pdurr...@amazon.com> > Cc: xen-devel@lists.xenproject.org; net...@vger.kernel.org; linux- > ker...@vger.kernel.org; Wei Liu <wei....@kernel.org>; Paul Durrant > <p...@xen.org>; David S. Miller <da...@davemloft.net> > Subject: Re: [PATCH net-next] xen-netback: support dynamic unbind/bind > > On Mon, Dec 23, 2019 at 09:59:23AM +0000, Paul Durrant wrote: > [...] > > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen- > netback/interface.c > > index f15ba3de6195..0c8a02a1ead7 100644 > > --- a/drivers/net/xen-netback/interface.c > > +++ b/drivers/net/xen-netback/interface.c > > @@ -585,6 +585,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, > grant_ref_t ring_ref, > > struct net_device *dev = vif->dev; > > void *addr; > > struct xen_netif_ctrl_sring *shared; > > + RING_IDX rsp_prod, req_prod; > > int err; > > > > err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif), > > @@ -593,7 +594,14 @@ int xenvif_connect_ctrl(struct xenvif *vif, > grant_ref_t ring_ref, > > goto err; > > > > shared = (struct xen_netif_ctrl_sring *)addr; > > - BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE); > > + rsp_prod = READ_ONCE(shared->rsp_prod); > > + req_prod = READ_ONCE(shared->req_prod); > > + > > + BACK_RING_ATTACH(&vif->ctrl, shared, rsp_prod, XEN_PAGE_SIZE); > > + > > + err = -EIO; > > + if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl)) > > + goto err_unmap; > > I think it makes more sense to attach the ring after this check has been > done, but I can see you want to structure code like this to reuse the > unmap error path.
Looks a little odd, agreed. The reason I did it this way is so that I can use RING_SIZE() rather than having to use __RING_SIZE(); makes the code just a little bit shorter... which reminds me I ought to neaten up blkback similarly. > > So: > > Reviewed-by: Wei Liu <wei....@kernel.org> > > Nice work btw. Thanks :-) Paul _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
