Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750865AbdCHFVp (ORCPT ); Wed, 8 Mar 2017 00:21:45 -0500 Received: from mail.kernel.org ([198.145.29.136]:59122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbdCHFVo (ORCPT ); Wed, 8 Mar 2017 00:21:44 -0500 Date: Tue, 7 Mar 2017 17:06:57 -0800 (PST) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Boris Ostrovsky cc: Stefano Stabellini , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, Stefano Stabellini , jgross@suse.com, Eric Van Hensbergen , Ron Minnich , Latchesar Ionkov , v9fs-developer@lists.sourceforge.net Subject: Re: [PATCH 6/7] xen/9pfs: receive responses In-Reply-To: Message-ID: References: <1488830488-18506-1-git-send-email-sstabellini@kernel.org> <1488830488-18506-6-git-send-email-sstabellini@kernel.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3444 Lines: 113 On Tue, 7 Mar 2017, Boris Ostrovsky wrote: > On 03/06/2017 03:01 PM, Stefano Stabellini wrote: > > Upon receiving a notification from the backend, schedule the > > p9_xen_response work_struct. p9_xen_response checks if any responses are > > available, if so, it reads them one by one, calling p9_client_cb to send > > them up to the 9p layer (p9_client_cb completes the request). Handle the > > ring following the Xen 9pfs specification. > > > > Signed-off-by: Stefano Stabellini > > CC: boris.ostrovsky@oracle.com > > CC: jgross@suse.com > > CC: Eric Van Hensbergen > > CC: Ron Minnich > > CC: Latchesar Ionkov > > CC: v9fs-developer@lists.sourceforge.net > > --- > > net/9p/trans_xen.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 53 insertions(+) > > > > diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c > > index 4e26556..1ca9246 100644 > > --- a/net/9p/trans_xen.c > > +++ b/net/9p/trans_xen.c > > @@ -149,6 +149,59 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > > > > static void p9_xen_response(struct work_struct *work) > > { > > + struct xen_9pfs_front_priv *priv; > > + struct xen_9pfs_dataring *ring; > > + RING_IDX cons, prod, masked_cons, masked_prod; > > + struct xen_9pfs_header h; > > + struct p9_req_t *req; > > + int status = REQ_STATUS_ERROR; > > > Doesn't this need to go inside the loop? Yes, thank you! > > + > > + ring = container_of(work, struct xen_9pfs_dataring, work); > > + priv = ring->priv; > > + > > + while (1) { > > + cons = ring->intf->in_cons; > > + prod = ring->intf->in_prod; > > + rmb(); > > > Is this rmb() or mb()? (Or, in fact, virt_XXX()?) You used mb() in the > previous patch. I think they should all be virt_XXX, thanks. > > + > > + if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) < sizeof(h)) { > > + notify_remote_via_irq(ring->irq); > > + return; > > + } > > + > > + masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE); > > + masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); > > + > > + xen_9pfs_read_packet(ring->ring.in, > > + masked_prod, &masked_cons, > > + XEN_9PFS_RING_SIZE, &h, sizeof(h)); > > + > > + req = p9_tag_lookup(priv->client, h.tag); > > + if (!req || req->status != REQ_STATUS_SENT) { > > + dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag); > > + cons += h.size; > > + mb(); > > + ring->intf->in_cons = cons; > > + continue; > > > I don't know what xen_9pfs_read_packet() does so perhaps it's done there > but shouldn't the pointers be updated regardless of the 'if' condition? This is the error path - the index is increased immediately. In the non-error case, we do that right after the next read_packet call, few lines below. > > + } > > + > > + memcpy(req->rc, &h, sizeof(h)); > > + req->rc->offset = 0; > > + > > + masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); > > + xen_9pfs_read_packet(ring->ring.in, > > + masked_prod, &masked_cons, > > + XEN_9PFS_RING_SIZE, req->rc->sdata, h.size); > > + > > + mb(); > > + cons += h.size; > > + ring->intf->in_cons = cons; Here ^ > > + if (req->status != REQ_STATUS_ERROR) > > + status = REQ_STATUS_RCVD; > > + > > + p9_client_cb(priv->client, req, status); > > + } > > } > > > > static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r) > > >