[PATCH 5/8] xen/9pfs: receive requests from the frontend

[Stefano Stabellini <sstabellini@kernel.org>]

Upon receiving an event channel notification from the frontend, schedule
the bottom half. From the bottom half, read one request from the ring,
create a pdu and call pdu_submit to handle it.

For now, only handle one request per ring at a time.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: anthony.perard@citrix.com
CC: jgross@suse.com
CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
CC: Greg Kurz <groug@kaod.org>
---
 hw/9pfs/xen-9p-backend.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/hw/9pfs/xen-9p-backend.c b/hw/9pfs/xen-9p-backend.c
index 59e89fd..d4c3d36 100644
--- a/hw/9pfs/xen-9p-backend.c
+++ b/hw/9pfs/xen-9p-backend.c
@@ -94,12 +94,59 @@ static int xen_9pfs_init(struct XenDevice *xendev)
     return 0;
 }
 
+static int xen_9pfs_receive(struct Xen9pfsRing *ring)
+{
+    struct xen_9pfs_header h;
+    RING_IDX cons, prod, masked_prod, masked_cons;
+    V9fsPDU *pdu;
+
+    if (ring->inprogress) {
+        return 0;
+    }
+
+    cons = ring->intf->out_cons;
+    prod = ring->intf->out_prod;
+    xen_rmb();
+
+    if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) < sizeof(h)) {
+        return 0;
+    }
+    ring->inprogress = true;
+
+    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.out, masked_prod, &masked_cons,
+                         XEN_9PFS_RING_SIZE, (uint8_t*) &h, sizeof(h));
+
+    pdu = pdu_alloc(&ring->priv->state);
+    pdu->size = h.size;
+    pdu->id = h.id;
+    pdu->tag = h.tag;
+    ring->out_size = h.size;
+    ring->out_cons = cons + h.size;
+
+    qemu_co_queue_init(&pdu->complete);
+    pdu_submit(pdu);
+
+    return 0;
+}
+
 static void xen_9pfs_bh(void *opaque)
 {
+    struct Xen9pfsRing *ring = opaque;
+    xen_9pfs_receive(ring);
 }
 
 static void xen_9pfs_evtchn_event(void *opaque)
 {
+    struct Xen9pfsRing *ring = opaque;
+    evtchn_port_t port;
+
+    port = xenevtchn_pending(ring->evtchndev);
+    xenevtchn_unmask(ring->evtchndev, port);
+
+    qemu_bh_schedule(ring->bh);
 }
 
 static int xen_9pfs_free(struct XenDevice *xendev)
-- 
1.9.1


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