xen/9pfs: receive responses

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.

CC: groug@kaod.org
CC: jgross@suse.com
CC: Eric Van Hensbergen <ericvh@gmail.com>
CC: Ron Minnich <rminnich@sandia.gov>
CC: Latchesar Ionkov <lucho@ionkov.net>
CC: v9fs-developer@lists.sourceforge.net

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 28f30f49d5dd..47864245c0d4 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -189,6 +189,62 @@ again:
 
 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;
+
+        ring = container_of(work, struct xen_9pfs_dataring, work);
+        priv = ring->priv;
+
+        while (1) {
+                cons = ring->intf->in_cons;
+                prod = ring->intf->in_prod;
+                virt_rmb();
+
+                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);
+
+                /* First, read just the header */
+                xen_9pfs_read_packet(&h, ring->data.in, sizeof(h),
+                                     masked_prod, &masked_cons,
+                                     XEN_9PFS_RING_SIZE);
+
+                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;
+                        virt_mb();
+                        ring->intf->in_cons = cons;
+                        continue;
+                }
+
+                memcpy(req->rc, &h, sizeof(h));
+                req->rc->offset = 0;
+
+                masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
+                /* Then, read the whole packet (including the header) */
+                xen_9pfs_read_packet(req->rc->sdata, ring->data.in, h.size,
+                                     masked_prod, &masked_cons,
+                                     XEN_9PFS_RING_SIZE);
+
+                virt_mb();
+                cons += h.size;
+                ring->intf->in_cons = cons;
+
+                status = (req->status != REQ_STATUS_ERROR) ?
+                        REQ_STATUS_RCVD : REQ_STATUS_ERROR;
+
+                p9_client_cb(priv->client, req, status);
+        }
 }
 
 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)