netmap: Drop netmap_can_send

This callback is called by main loop before polling s->fd, if it returns
false, the fd will not be polled in this iteration.

This is redundant with checks inside read callback. After this patch,
the data will be copied from s->fd to s->iov when it arrives. If the
device can't receive, it will be queued to incoming_queue, and when the
device status changes, this queue will be flushed.

Also remove the qemu_can_send_packet() check in netmap_send. If it's
true, we are good; if it's false, the qemu_sendv_packet_async would
return 0 and read poll will be disabled until netmap_send_completed is
called.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1433400324-7358-5-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

net/netmap.c

@@ -132,23 +132,13 @@ static int netmap_open(NetmapPriv *me)
     return -1;
 }
 
-/* Tell the event-loop if the netmap backend can send packets
-   to the frontend. */
-static int netmap_can_send(void *opaque)
-{
-    NetmapState *s = opaque;
-
-    return qemu_can_send_packet(&s->nc);
-}
-
 static void netmap_send(void *opaque);
 static void netmap_writable(void *opaque);
 
 /* Set the event-loop handlers for the netmap backend. */
 static void netmap_update_fd_handler(NetmapState *s)
 {
-    qemu_set_fd_handler2(s->me.fd,
-                         s->read_poll  ? netmap_can_send : NULL,
+    qemu_set_fd_handler2(s->me.fd, NULL,
                          s->read_poll  ? netmap_send     : NULL,
                          s->write_poll ? netmap_writable : NULL,
                          s);
@@ -317,7 +307,7 @@ static void netmap_send(void *opaque)
 
     /* Keep sending while there are available packets into the netmap
        RX ring and the forwarding path towards the peer is open. */
-    while (!nm_ring_empty(ring) && qemu_can_send_packet(&s->nc)) {
+    while (!nm_ring_empty(ring)) {
         uint32_t i;
         uint32_t idx;
         bool morefrag;